Special Educational Needs and Disabilities

Vignette 3: Complexity of perceptions of fairness within appeals (Parent 5).

6. Special Educational Needs and Disabilities

Grossly, colorectal carcinomas were mainly of three macroscopic patterns, namely annular - constricting, exophytic/fungating, or flat infiltrating/ulcerating masses. The commonest gross

lesions, 58 (43.3%) and diffusely infiltrating/ulcerative lesions 10 (7.4%). Three cases (2.23%) of adenomatous polyps co-existed with colorectal carcinoma, and they included 2 cases of villous adenoma and 1 case of tubulo-villous adenoma. (Figure 1)

Exophytic growth pattern was the most common macroscopic appearance (77.3%) of right sided colorectal carcinomas in both sexes and ages between 41-70 years. Annular constricting pattern (18.2%) and diffusely infiltrating/ulcerative pattern (4.5%) were other types seen. The commonest macroscopic appearance of left sided colorectal carcinomas was annular constricting lesions (55.6%), which were seen in both sexes and ages between 31-70 years. Exophytic/ polypoidal / fungating lesions (35.6%) and diffusely infiltrating/ulcerative lesions (8.8%) were other types seen. (Table 4)

5.4 Histological Types of Colorectal Carcinoma

The predominant histological type was adenocarcinoma (79.9%) showing varying degrees of differentiation with the well-differentiated type predominating in 62 (46.3%) cases. Mucinous adenocarcinoma (17.2%), anaplastic carcinoma (2.2%) and signet ring carcinoma (0.7%) were other types seen (Table 5).

Of the 23 cases of mucinous carcinoma, 13 (56.5%) were seen in the males giving a male to female ratio of 1.3: 1. Most cases of mucinous carcinoma in males (34.8%) were seen in younger population with a peak incidence in the 31-40 years age group while most cases in the females (39.1%) were seen in older population with the peak incidence in 51-60 years age group. The only case (0.7%) of signet ring carcinoma was seen in male aged 16 years old. (Table 6)

5.5.2 Anatomic Site Distribution of the Histological Types of Colorectal Carcinoma

Adenocarcinomas were the most common histologic type of right sided and left sided colorectal carcinomas in 34 (25.40%) and 73 (54.5%) cases respectively. Mucinous carcinomas constituted 10 (7.5%) and 13 (9.7%) cases of right sided and left sided colorectal carcinomas respectively. Anaplastic carcinomas and signet ring carcinoma were seen only in left sided colorectal carcinomas in 3 (2.2%) and 1 (0.7%) cases respectively. (Table 6)

5.6 Pattern of Colorectal Carcinomas in patients 40 years and below

Of the 134 patients with colorectal carcinomas, 31 were aged 40 years and below. Twenty-one (63.6%) were from male patients while twelve (36.4%) were females giving a male to female ratio of 1.8:1. The age range was from 15 years to 40 years with a mean age of 33.09 (STD + 6.3) years. Left sided carcinomas predominated, 21 (67.8%) cases and the remaining cases, 12 (36.4%) were right sided carcinomas. Right-sided colorectal carcinomas were predominantly of exophytic/fungating pattern, 7(10.6%) while the left-sided colorectal carcinomas were predominantly annular-constricting pattern, 12 (20.7%) of total specific macroscopic type. Adenocarcinomas and mucinous carcinomas were two main histologic types of right-sided colorectal carcinomas in 7 (6.5%) and 5 (21.7%) cases respectively. Adenocarcinomas were the commonest histologic type of left sided colorectal carcinomas, 13 (12.2%). Mucinous carcinoma 6(26.1%), anaplastic carcinoma, 1 (33.3) and only case of signet-ring carcinomas were other types seen.

5.7 Pattern of Colorectal Carcinomas in patients 40 years and above

Of the 134 patients with colorectal carcinomas, 101were aged 40 years and above. The age range was from 41 years to 81 years with a mean age of 58.1 (STD + 10.3) years with a male to female ratio of 1.7:1. Left sided carcinomas predominated, 69 (68.3%) cases and the remaining cases, 32

exophytic/fungating pattern, 27 (40.9%). The commonest gross appearance of the left-sided colorectal carcinomas was annular-constricting pattern, 38 (65.5%). Exophytic/fungating pattern, 25 (37.9%) and diffusely infiltrating/ulcerative pattern 6 (60.0%) were other types seen (Table 4). Adenocarcinomas and mucinous carcinomas were two main histologic types of right-sided colorectal carcinomas in 27(25.2%) and 5(21.7%) cases respectively. Adenocarcinomas were the commonest histologic type of left sided colorectal carcinomas, 60 (56.1%). Mucinous carcinoma, 7 (30.4%), and anaplastic carcinoma, 2 (66.7%) were other types seen. (Table 6)

5.8 Staging using Astler Coller, Dukes and TNM staging system.

The operative findings in respect of extent of disease, especially nodal involvement, were documented adequately in 98 cases, thus allowing staging to be undertaken. In 26 (26.5%) patients, the disease was very advanced at presentation; 1 of the 98 patients with colorectal carcinoma (1.02%) had distant metastases while 25 of the 98 patients (25.5%) had regional lymph node involvement.

Sixty- nine patients were classified as either Astler Coller Stage B1 in 10 cases (10.2%) or B2 in 59 cases (60.2%) whereas 28 patients had Astler Coller Stage C1 in 8 cases (8.16%) or C2 in 20 cases (20.4%). The remaining one (1.02%) case had Astler Coller Stage D.

Eighty- nine patients were classified as either Duke Stage B, 64 cases, (65.31%) or C, 25 cases, (25.51%) whereas 8(18.6%) patients had Duke Stage A. Only 1 (1.02%) patient was classified as Stage D with distant metastasis to the liver.

Most patients presented with TNM Staging system of T3N0M0 in 53 (54.10%) cases which corresponded to Stage IIA. About twenty (19.39%) percent were in T3N1M0 (Stage IIIB), 10.20% in T4N0M0 (Stage IIB), 9.18% in T2N0M0 (Stage I), 6.12% in T2N1M0, and 1.02% in T4N0M1 (Stage IV). (Table 7)

There are statistically significant positive (nonparametric) correlation between Astler Coller, TNM staging system and Dukes staging system (Spearman ^,s rho correlation coefficient = 1, p = 0.01) (Table 8 & 9)

5.8.1 TNM staging system with Age and Sex Distribution

Seventy- two patients with colorectal carcinoma presented in early stage (stage I and II) with male to female ratio of 1.3: 1. Their peak age incidences were in the age groups 51-60 years and 41-50 years respectively. Similarly, the remaining 26 patients presented late with slight male preponderance and male to female ratio of 1.2: 1. Their peak age incidences were in the age groups 51-60 years and 61-70 years respectively. (Table 10)

5.9 Comparing Frequencies of Colorectal Carcinomas in Nigeria

The frequency of colorectal carcinomas in different parts of the country varies with increasing tendencies. The average yearly frequency of colorectal carcinomas in centres depicted in the table 11 was 12.5 cases which is below 17 cases per annum recorded in this present study.

6.0 Comparison of Results of present study with studies from other centres in Nigeria, Africa and other parts of the World.

Most studies in studies in Africa recorded peak age incidence of 41-50 years for colorectal carcinomas with a male preponderance and adenocarcinoma was the predominant histologic type seen. Outside Africa, the peak age incidence for colorectal carcinoma was 60- 70 years with a slight male preponderance. The present study recorded peak age incidence of 41-50 years for colorectal carcinomas with a male preponderance and adenocarcinoma was the predominant histologic type seen (Table 12).

Table 1: Age and Sex Distribution of Colorectal Carcinomas

Age (years) Males Females Total no. of Patients

Percentage (%)

11-20 2 1 3 2.20%

21-30 5 3 8 6.00%

31-40 14 8 22 16.40%

41-50 15 17 32 23.90%

51-60 22 15 37 27.60%

61-70 14 8 22 16.40%

71-80 5 4 9 6.70%

80-90 1 - 1 0.80%

Total 78 56 134 100.0%

Table 2: Main Gastrointestinal Presentation in Patients with Colorectal Carcinoma

Age (years) Alteration Rectal Large bowel Abdominal Faecal Total in bowel bleeding obstruction mass incontinence

habit

M F M F M F M F M F M F

11-20 1 - 1 - - - - 1 - - 2 1 21-30 1 1 1 1 - 1 1 1 1 - 4 4 31-40 2 1 5 2 2 3 4 1 1 1 14 8 41-50 2 2 7 5 4 2 3 5 - 2 16 16 51-60 4 3 9 4 3 6 2 4 1 1 19 18 61-70 1 - 6 2 5 5 2 - - 1 14 8 71-80 - 1 - 1 2 - 3 1 1 - 6 3 81-90 1 - - - - - - - - - 1 - Subtotal 12 8 29 15 16 17 15 13 4 5 76 58

Total

with 20 44 33 28 9 134 Percentage 14.9% 32.8% 24.6% 20.9% 6.7% 100.0%

Table 3: Anatomical Distribution of the Colorectal Carcinomas.

Anatomical Sites Numbers of Case Percentage (%) Caecum 19 14.2

Ascending colon 11 8.2

Right flexure 4 3.0

Transverse colon 7 5.2

Left flexure 3 2.2

Descending colon 4 3.0

Sigmoid colon 16 11.9

Rectum 70 52.2

Total 134 100.0

Table 4: Macroscopic Patterns of Colorectal Carcinoma with Age, Sex and Anatomic Site Distribution.

Right sided colorectal carcinomas Left sided colorectal carcinomas

Age Exophytic/ Annular- Diffusely Exophytic/ Annular- Diffusely Total (Years) Fungating Constricting infiltrating Fungating constricting infiltrating

M F M F M F M F M F M F M F 11-20 1 - 1 - - - - 1 - - - - 2 1 21-30 1 1 1 1 - 1 1 - - 1 - 1 3 5 31-40 3 1 1 - - - 4 1 6 5 - 1 14 8 41-50 2 6 - - - - 3 5 8 5 2 1 15 17 51-60 4 6 - - - - 5 4 12 4 1 1 22 15 61-70 6 1 - 2 - - 4 - 4 5 - - 14 8 71-80 - 1 1 1 1 - 3 1 - - - 1 5 4 81-90 1 - - - - - - - - - - - 1 - Subtotal 18 16 4 4 1 1 20 12 30 20 3 5 76 58

Total

with 34 8 2 32 50 8 134 Percentage 25.4% 6.0% 1.5% 23.9% 37. 3% 6.0% 100.0%

Table 5: Histological Distribution of Colorectal Carcinoma

Histological Types No of Cases Percentage (%) Well differentiated 62 46.30

Moderately differentiated 25 18.70 Poorly differentiated 20 14.90 Mucinous carcinoma 23 17.20 Anaplastic carcinoma 3 2.20

Signet- ring carcinoma 1 0.7 Total 134 100.0

Table 6: Histological Types of Colorectal Carcinoma with Age, Sex and Anatomic Site Distribution.

Right sided colorectal carcinomas Left sided colorectal carcinomas

Age Adeno- Mucinous Adeno- Mucinous Anaplastic Signet-ring Total (Years) carcinoma carcinoma carcinoma carcinoma carcinoma carcinoma

M F M F M F M F M F M F M F 11-20 - 1 1 - - - - - - - 1 - 2 1 21-30 1 - 1 1 2 1 1 1 - - - - 5 3 31-40 2 3 2 - 6 4 3 1 1 - - - 14 8 41-50 3 4 1 - 10 11 1 1 1 - - - 16 16 51-60 7 4 - - 19 2 2 3 - - - - 28 9 61-70 5 1 - 2 7 6 - - 1 - - - 13 9 71-80 1 1 1 1 3 2 - - - - - 5 4 81-90 1 - - - - - - - - - - - 1 - Subtotal 20 14 6 4 47 26 7 6 3 - 1 - 84 50

Total

with 34 10 73 13 3 1 134 Percentage 25. 4% 7. 5% 54. 5% 9.7% 2. 2% 0.7% 100.0%

Table 7: Staging of colorectal carcinoma using Astler - Coller, Dukes and TNM staging system.

Astler – Coller Dukes TNM STAGE A

B1 10 (10.2%) A 8(8.16%) T2N0M0 9(9.18%) I 9(9.18%) B2 62 (63.3%) B 64(65.31%) T3N0M0 53(54.1%) IIA 53(54.08 %) T4N0M0 10(10.2%) IIB 10(10.2%) C1 5(5.1%) C 25(25.51%) T2N1M0 6(6.12%) IIIA 6(6.1 2%) C2 20(20.4%) T3N1M0 19(19.39%) IIIB 19(19.39%) D 1(1.02%) D 1(1.02%) T4N0M1 1(1.02%) IV 1(1 .02%) TOTAL 98(100.0%) 98(100.0%) 98(100.0%) 98(100.0%)

Table 8: shows Positive significant Correlations between Astler Coller and Dukes staging systems

Correlations

1.000 1.000*

. .042

4 4

1.000* 1.000

.042 .

4 4

1.000 1.000**

. .

4 4

1.000** 1.000

. .

4 4

Correlation Coef f icient Sig. (2-tailed)

N ASTLERCO

DUKES

ASTLERCO

DUKES Kendall's t au_b

Spearman's rho

ASTLERCO DUKES

Correlation is signif icant at t he .05 lev el (2-tailed).

Correlation is signif icant at t he .01 lev el (2-tailed).

**.

Table 9: shows Positive significant Correlations between TNM and Dukes staging systems

Correlati ons

1.000 1.000*

. .042

4 4

1.000* 1.000

.042 .

4 4

1.000 1.000**

. .

4 4

1.000** 1.000

. .

4 4

Correlation Coef f icient Sig. (2-tailed)

N DUKES

TNM

DUKES

TNM Kendall's tau_b

Spearman's rho

DUKES TNM

Correlation is signif icant at the .05 lev el (2-tailed).

Correlation is signif icant at the .01 lev el (2-tailed).

**.

Table 10: TNM staging system of Colorectal Carcinoma with Age and Sex Distribution

TNM Staging

Stage I IIA IIB IIIA IIIB IV Total Age (T2N0M0) (T3N0M0) (T4N0M0) (T2N1M0) (T3N1M0) (T2N0M0)

years M F M F M F M F M F M F M F

11-20 - - - - - - - - 1 1 - - 1 1 21-30 2 - 2 1 - - - - 1 - - - 5 1 31-40 2 - 5 6 - - - - 2 2 - - 9 8 41-50 - - 5 7 1 2 1 1 2 2 - - 9 12 51-60 - 4 8 4 3 - 2 - 3 2 - 1 16 11 61-70 1 1 6 3 1 - - - 2 3 - - 10 7 71-80 1 - 2 3 1 1 - - - - - - 4 4 81-90 - - - - - - - - - - - Subtotal 6 5 28 24 6 3 3 1 11 10 - 1 54 44

Total 11 52 9 4 21 1 98

With

Percentage 11.2% 53.1% 9.2% 4.1% 21.4% 1.02% 100 .0%

Table 11: shows comparing frequencies of colorectal carcinomas in Nigeria

Authors Years Centres No of cases No of years Annual frequency under study

Nwofo DC et al⁶ 1990 Enugu 34 7 4.9 Iliyasu Y et al⁷ 1990 Ibadan 506 20 25.3 Elesha SO et al⁹ 1998 Lagos 216 15 14.4 Sule AZ et al⁸ 2001 Jos 144 10 14.4 Seleye-D et al¹³ 2005 Port Harcourt 45 12 3.8 Ibrahim O et al¹²2005 Ilorin 138 23 6.0 Edino ST et al³⁸ 2005 Kano 50 4 12.5 Present study 2009 Lagos 170 10 17.0

Table 12: Comparison of Results of present study with studies from other centres in Nigeria, Africa and other parts of the World.

Authors Centres Peak age Male/Female Predominant Predominant incidence sex ratio anatomic site histologic (years) type

Adekunle OO et al³⁷ Ibadan (SW Nigeria) 41-50 1.4:1 rectum adenocarcinoma Nwofo DC et al⁶ Enugu (SE Nigeria) 41-50 2.2:1 rectum adenocarcinoma Seleye – Port Harcourt

Dubare et al¹³ (SS Nigeria) 50-59 3.1:1 rectum adenocarcinoma Sule AZ et al⁸ Jos (NC Nigeria) 41-50 1.5:1 rectosigmoid region adenocarcinoma Edino ST et al38 Kano (NW Nigeria) 41-50 2.5:1 rectum adenocarcinoma Naaeder SB et al³⁹Ghana (Western Africa) 71-80 1:1 rectum adenocarcinoma Angelo N et al⁴² South Africa 41-50 1.6:1 rectosigmoid region adenocarcinoma Sebti MF et al⁴⁵ Morocco (North Africa) 41-50 3.2:1 recto - sigmoid region adenocarcinoma Coleman N et al⁴⁸ England (Europe) 61-70 1.2:1 colon adenocarcinoma Anderson WF et al⁵⁴United State 65-70 1.1:1 rectosigmoid region adenocarcinoma Present study Lagos (SW Nigeria) 51-60 1.4:1 rectum adenocarcinoma

Figure 1: Distribution of Macroscopic Appearance of Colorectal carcinomas

Exophytic/polypoidal /fungating Annular-constricting 50%

43%

Diffusely infiltrating/ulcerative

Exophytic/polypoidal/fungating Annular-constricting

Diffusely infiltrating/ulcerative

Figure 2: Photomicrograph of colon showing well differentiated adenocarcinoma.

H & E X 100

Figure 3: Photomicrograph of colon showing mucinous carcinoma. H & E. X 100

Figure 4: Photomicrograph of colon showing mucinous carcinoma. Periodic Acid Schiff (PAS) X 100

Figure 5: Photomicrograph of colon showing signet-ring carcinoma. H & E. X 100

Figure 6: Photomicrograph of colon showing anaplastic carcinoma. H & E. X 100

Figure 7: Photomicrograph of lymph node showing metastasis of colonic adenocarcinoma. H & E. X 40

CHAPTER 6 DISCUSSION

Colorectal carcinoma was once thought to be rare in Africa including Nigeria compared to Western world but it is now known to be on the increase. Nwofo and Ojukwu at Enugu in 1980 reported 34 cases in 7 years giving a yearly incidence of 4.9 ⁶. Iliyasu et al, at Ibadan in 1990 reported 506 cases in 20 years with an annual incidence of 25.3 ⁷. Sule, at Jos in 2001 reported 144 cases in 10 years with a yearly incidence of 14.4 ⁸. Previous study from this center recorded 216 cases of colorectal carcinoma over a 15 year period giving an annual incidence of 14.4 ⁹ . In this study, we recorded 170 cases of histologically confirmed colorectal carcinoma giving a relative occurrence of 17 cases per year. This increase in trend has been attributed to various factors including adoption of Western diets with low fibre, rural-urban migration, increase in the standard of living, and increased accessibility of medical services to the general population. Also, there is tendency to under - reporting colorectal carcinomas in this part of the world because of the inadequate diagnostic and screening facilities especially in the younger population, low level of health consciousness of medical practitioners in rural areas and in private clinics, and eagerness of some patients to patronize traditional herbalists for treatment rather than visiting hospitals ^8,9,34.

The age range in this study was from 15 years to 81 years with the peak age between 51 and 60 years. The mean age was 50.8 years whilst modal age and median age were 60 years and 51years respectively. This finding contrasts previous study from this center where a mean age of 47.3 years was reported ⁹. The mean age reported from various parts of Nigeria varied between 36 to 53.5 years 8, 12, 34, 37, 38. Also, studies from Morocco and South Africa recorded mean age of 46.6 and 54.3 years

respectively ^{45, 41}; while studies from England and United States recorded mean ages of 69.09 years and 72 years respectively ^{49, 53}. The peak age of occurrence reported from various parts of Nigeria varied between 40 and 69 years 6, 7, 12, 13, 31, 32, 33, 36. These findings contrast previous studies from Ghana and USA where peak ages between 70 and 80 years were recorded ^{39, 53}. From the foregoing, it is obvious that colorectal carcinomas occurred at a relatively younger age in Africans including Nigeria, compared to Caucasians. This may be explained by the varying biology of colorectal carcinomas in different geographical locations, and prompt and early treatment of pre-malignant lesions including inflammatory bowel disease, polyposis coli, diverticular disease and adenomatous polyps in the Caucasians.

Similar to previous studies from Nigeria, this study showed slight male preponderance with a male to female ratio of 1.4: 1 7- 9, 12, 33 - 35. In contrast, however, Ojo in Ile-Ife, Nigeria recorded a male to female ratio of 2.28:1 while Edino in Kano, Nigeria reported a male to female ratio of 2.5:1 ^{33, 38}. From other parts of Africa, and Europe, the trend is also similar with male gender predominating ^{40, 43,}

41, 48, 50, 52. In contrast, however,Elmasri and Boulou in Sudan recorded a male to female ratio of 5.3:1

10 which is quite greater than findings reported in this study and most parts of Nigeria. However, the reason for this slight male preponderance worldwide is unknown.

This study showed that the rectum or rectosigmoid was the site of predilection (70 patients, 52.0% or 86 patients, 64.2% respectively) for colorectal carcinomas with the colon to rectum ratio of 1:1.09. Also, left sided carcinomas predominated in 93 (69.4%) cases and the remaining cases, 41 (30.6%) were right sided carcinomas. This is consistent with findings in previous studies from this center, other centers in Nigeria and also world wide 6, 8, 9, 12, 15, 32 - 34, 36. In contrast, study from South-Africa reported colon especially caecum to be the predominating anatomic site for colorectal

This is in contrast to the finding of Ojo who reported descending colon as the 2^nd most common anatomic site (23.2%), followed by caecum (12.2%) ³³. Ponz de Leon et al in Modena, Northern Italy reported that two-thirds of colorectal carcinomas are right sided in contrast to other recent studies in America which suggest a trend towards anincrease of left-sided tumours 52, 53, 54, 79, 80. Jie Huang et al in their study in Singapore found that incidence rates of colorectal carcinoma has increased rapidly with the proportion of left sided colorectal carcinomas was found to have increased from 23.2% to 24.4% over the past 25 years whereas those for the right sided colorectal carcinomas were fairly consistent ⁵⁶ .

The reasons for these varying anatomic sites for colorectal carcinomas remain unclear, although they could also be attributed to different criteria adopted for the division of the colorectum into anatomical subsites.Other possible explanations for the different distributionof colorectal carcinomas into right and left sided segmentsmight include (i) the impact of environmental risk factors,such as diet and lifestyle ⁵⁷ ; (ii) differences in frequencyof hereditary colorectal neoplasms especially those preceded by HNPCC (which are characterizedby an increased frequency of right-sided lesions) ⁶⁹; and (iii) a more or less extensive use of colonoscopy ⁹⁰. Furthermore, experimental studies on preferential anatomic sites for colorectal carcinoma in different geographical regions need to be exploited. It should be noted that only a few centers perform colonoscopy in Nigeria and in majority of cases, sigmoidoscopy is the common practice.

Exophytic growth pattern was the most common macroscopic appearance of colorectal carcinomas (49.3%), as well as right sided colorectal carcinomas (77.3%) in both sexes and ages between 41-70 years. Annular constricting pattern was the 2^nd most common macroscopic pattern of colorectal carcinoma (43.3%) as well as the predominating type in left sided colorectal carcinomas (55.6%), which were seen in both sexes and ages between 31-70 years. The diffusely infiltrating/ulcerative lesion was the least type (7.4%). This finding is in conformity with the general

observation that right sided colorectal carcinomas tend to be polypoidal fungating type and that left sided colorectal carcinomas tend to be annular-constricting type ^{7, 9, 30}. On the contrary, Ajao in Ibadan, Nigeria reported that majority of the colorectal carcinomas tend to be annular constricting types ³². These differences may be partly explained by the fact that 58.6% of neoplasms were located in the rectum, where they infiltrate into the intestinal wall causing lesions which range from mucosal ulceration to intestinal stricture.

In our study, colorectal carcinoma was associated with 3 adenomatous lesions (2.23%) which included 2 cases of villous adenoma and 1 case of tubulo-villous adenoma. Previous study also from this center and Ile-Ife, South Western Nigeria recorded that villous adenoma was the most common mucosal lesion encountered in association with colorectal carcinoma ^{9, 33}. However, neither associated amoebic colitis nor schistosomiasis was seen, which contrasts with the finding of Ojo who reported amoebic colitis in 6.1% and schistosomiasis in 3.7% cases ³³. The presence of higher incidence of colorectal carcinomas is commonly seen in patients with adenomatous polyps compared to those without polyps ²⁷. The potential for malignant transformation is said to be higher in villous and tubulovillous adenomas than for tubular adenomas ²⁷. In 1993, the National Polyp Study Workgroup concluded that colonoscopy-guided polypectomy lowered the incidence of unexpected colorectal cancer, supporting the view that colorectal adenomas tend to progress to carcinomas ²⁷. It is also noteworthy that familial or multiple polyposis of the colon is distinctively rare in Africa including Nigeria and that the low incidence of recto-sigmoid adenomatous polyps contribute to low incidence of preventive and curative colonoscopy as well as polypectomy which is contrary to findings in Caucasians ^{9, 27, 30}.

The predominant histological type was adenocarcinoma (79.9%) showing varying degree of differentiation with the well differentiated type predominating in 62 (46.30%) cases. This is similar to

carcinoma was the 2^nd most common histological type (17.2%), as well as the 2^nd leading histological type for both right sided and left sided colorectal carcinomas which constituted 10 (7.5%) and 13 (9.7%) cases respectively. This finding compares relatively with the finding of Ibrahim in Ilorin, Nigeria who reported mucinous adenocarcinoma to have constituted 18.2% ¹² but contrasts finding from earlier study in this center where mucinous adenocarcinoma represented 24.8% ⁹. On the other hand, Ojo in Ile-Ife, South Western Nigeria reported a lower figure of 7.3% for mucinous adenocarcinoma ³³.

Most cases of adenocarcinoma, 67 (62.6%) were seen in the males with peak in the age group 51-60 years while 40 (37.4%) cases were seen in the females with the peak in age group 41- 50 years, a decade earlier compared to the males. This finding concurs with previous study from this center in which a male preponderance and a similar peak age incidence of 41-50 years for both males and females was recorded for adenocarcinoma histological types ⁹. In this study, mucinous carcinoma was also seen more commonly in males with a male to female ratio of 1.3: 1. Most cases of mucinous carcinoma in males (34.8%) were seen in younger population with a peak incidence in the 31-40 years age group while most cases in the females (39.1%) were seen in older population with the peak incidence in 51-60 years age group. This finding concurs with previous study in Ilorin, Nigeria where mucinous adenocarcinoma constituted the majority (59.3%) of colorectal carcinoma seen below 50 years ¹². The predominance of mucinous carcinoma in males and in younger patients in this study and other previous similar studies concurs with the general observation that mucinous carcinoma tends to have predilection for males and younger age groups, although no reasons have been suggested for this prevalence 16, 19, 20, 23, 46.

Mucinous carcinoma in this study was commonly located in the left side which contrasts the observation in the literature that mucinous carcinoma tends to be right sided, and is associated with a less favourable prognosis, and HNPCC which has high level of DNA microsatellite instability (MSI)

as a useful prognostic marker ^{14, 69}. This difference may be due to varying sample sizes which is smaller in this study. Anaplastic carcinoma and signet ring carcinoma were other histological types seen, predominantly in the left sided colorectal carcinomas in 3 (2.2%) and 1(0.7%) cases respectively, similar to other studies in Nigeria ^{7, 33}.

Although reports have shown that colorectal carcinoma can occur in any age group, it is uncommon in the younger population 12, 23, 31, 32, 39. In this study, thirty-one (23.1%) patients with colorectal carcinoma were aged 40 years and below with a mean age of 33.09 years and male to female ratio of 1.8:1. In this younger population, left sided carcinomas predominated while adenocarcinoma was the commonest histologic type.

Mucinous carcinoma constituted 11(47.8%) cases in younger population which is a little less than relative frequency of 12 (52.2%) cases seen in older population; with a male to female ratio of 1:1.1. The only case of signet-ring carcinoma was left sided while one case of anaplastic carcinoma was seen. Similar to previous studies from Nigeria, this study showed slight male preponderance with a male: female ratio ranging from 1.2:1 to 1.4:1 and preponderance of adenocarcinoma as well as left sided lesions 25, 33, 36 . In contrast, however, Ameh et al in Zaria, Nigeria recorded no sex difference between the 8 patients studied in which mucinous carcinoma predominated ¹⁷. From other parts of Africa, the age, sex prevalence and histologic type are also similar to our findings 42 - 44, 46. From the foregoing, it is obvious that incidence of colorectal carcinoma is on the increase in the younger population in Africa including Nigeria compared to developed countries and more studies are required to determine the biology of this tumour in them. Occurrence of CRC in a younger age has been associated with germline genetic abnormality and high suspicion of hereditary polyposis syndromes or HNPCC 12, 14 -16, 69. Also, the cancers that arise from this syndrome differ from the sporadic form by an increased frequency of right-sided tumours (60% to 70%), an excess of metachronous colorectal

69. Also, colorectal carcinoma should be entertained as a differential diagnosis, even in a younger population with provisional diagnosis of rectal granuloma, ameboma, tuberculosis, rectal schistosomiasis and adult chronic intermittent intussusception ^{32, 37}.

In our study, rectal bleeding was the most common clinical presentation in 44 (32.8%) patients and these patients also presented with severe anaemia. This finding concurs with previous study from Jos and Ibadan, Nigeria where rectal bleeding was reported as the commonest presenting clinical feature 8, 25, 32, 37. In contrast to our findings, however, studies from Ile-Ife, South Western Nigeria recorded alteration of bowel habits as the most common symptom ^{33, 34}. Previous studies from the rest of the Africa and Western world reported these major clinical presentations in varying proportions, which included abdominal pain, change in bowel habit, haematochezia or melaena, weakness, anaemia without other gastrointestinal symptoms and weight loss 10, 31, 32, 37, 41, 44, 49. Generally, however, the clinical presentation is determined by the anatomic sites of colorectal carcinoma such as right sided carcinomas tend to present with rectal bleeding whereas the left (distal) lesions tend to present with features of intestinal obstruction ^{15, 86}. The two predominating clinical features in this series were rectal bleeding and features of intestinal obstruction which may be related to the marked predilection of these carcinomas for rectum or rectosigmoid region where they tend to cause progressive luminal narrowing.

This study showed that the disease was advanced (Stages III & IV) in 26 (26.5%) cases. Also, the advanced stage of colorectal carcinoma has slight male preponderance with a male to female ratio of 1.2:

1, slightly lower than that from the general population and these were seen commonly in the patients 40 years and above in 19, (19.4%) cases. The incidence of advanced stage of colorectal carcinoma was reported to be varied from 14% to 75% in other parts of Nigeria 9, 31 - 33, 37. In contrast to our findings, studies from Europe and USA reported that more patients with colorectal carcinoma presented in early (localized) stage (stage I and II) ^{52, 55}. From the foregoing, it is obvious that patients with colorectal carcinomas presented late in Africa including Nigeria, than patients from Europe and USA, which is

characterized by dismal prognosis. However, most of the available literatures do not use TNM staging system for colorectal carcinoma but they rather used either Astler- Coller staging system ^{9, 31, 37} or Dukes staging system ³³.

This study shows statistically significant positive correlations between the three staging systems used for colorectal carcinoma, which conforms with the fact that the Astler-Coller and TNM staging systems compare relatively well with Dukes staging system. However, most of the available literatures do not consider correlations between the three staging system 9, 31, 33, 37, 84, 85 . Although the original Dukes' staging system ⁸⁴ has been modified, the depthof disease invasion through the bowel wall and the extent of regional lymph-node involvement remain the core of the staging system. The tumor–node–

metastasis (TNM) system ofthe American Joint Committee on Cancer is now the most commonlyused system for staging colorectal cancer and serves as a benchmarkfor predicting the likelihood of five-year survival⁹⁴. The TNM staging system has the advantage over the Dukes^, system in distinguishing early tumours involving only the submucosa (T1) and amenable to endoscopic resection, from slightly more advanced tumours (T2) which extend to the muscularis propia ⁹⁴.

Prevention of colorectal carcinomas is multidimensional and include regular endoscopy, genetic surveillance of high risk group such as first degree relatives of patients with polyposis syndromes, prophylactic surgery; for examples colectomy, chemoprevention and lifestyle modification through promotion of health education 8,9, 26, 27.

CONCLUSION

This study showed that the annual frequency of colorectal carcinoma appears to be increasing and peak age is in the fifth decade of life, a decade earlier than in Caucasian patients. It was relatively predominantly located in the rectum or rectosigmoid region. Adenocarcinoma was the main histologic type in both younger and older populations. Mucinous carcinoma was more common in younger populations.

RECOMENDATIONS

The national health policy should focus on promotion of health education and screening programmes for prevention and early diagnosis of colorectal carcinoma which in turn will decrease the morbidity and mortality rates associated with this disease. Perhaps a vigorous promotion of colonoscopy in both younger and older populations and large-scaleresearch studies evaluating faecal occult blood testing could enhance prompt detection of colorectal carcinoma and thus reducing the number of patients who present with advanced disease. In my opinion, the TNM staging system of reporting of colorectal carcinoma should be encouraged among pathologists because it is better for the management of patients with colorectal carcinoma with advantages of improved international communication between pathologists, surgeons and oncologists, as well as serving as a benchmarkfor predicting the likelihood of five-year survival.

APPENDIX

Dukes Staging System:

A: Tumour does not grow beyond muscularis propia, B: Tumour grows beyond muscularis propia, C: Lymph node metastases with the tumour, and

D: Distant metastases (Added by Turnbull).

Astler-Coller Staging System:

A: Tumour limited to mucosa (carcinoma–in-situ.), B1: Tumour grows through muscularis mucosa but not through muscularis propia, B2: Tumour grows beyond muscularis propia,

C1: Stage B1 with regional lymph node metastases,

C2: Stage B2 with regional lymph node metastases, and D: Distant metastases.

(Edited from Ramzi S.Cotran, Vinay Kumar and Tucker Collins: The Endocrine System, A Textbook of Robbins Pathologic Basis of Disease, sixth edition, Philadelphia, USA, W.B. Saunders Company, 1999, pg 827-835).

TNM Staging System / Classification:

T: Assesses the tumour stage:

TX: Primary tumour cannot be assessed, T0: No evidence of primary tumour, Tis: Carcinoma-in-situ limited to mucosa

T1: Tumour invades submucosa but not through muscularis propia, T2: Tumour invades muscularis propia but not beyond,

T4: Tumour perforates visceral peritoneum or invades other organs or structures (including other loops of bowel).

N: Assesses the regional lymph node stage:

NX: Regional lymph node cannot be assessed, N0: No regional lymph node metastases, N1: 1-3 regional lymph node metastases, N2: 4 or more regional lymph node metastases, and

N3: Regional lymph node metastases along named vascular trunks,

M: Assess distant metastases:

MX: Distant metastases cannot be assessed, M0: No distant metastases, and

M1: Distant metastases.

Stage Grouping:

Stage 0: Tis, N0, M0,

Stage I: T1 or T2, N0, M0 (Dukes A), Stage II: T3 or T4, N0, M0 (Dukes B),

Stage III: Any T, N1, N2, or N3, M0 (Dukes C), Stage IV: Any T, any N, M1 (Dukes D).

TABLE OF STAGING GROUPING COMPARING TNM, DUKES AND MODIFIED ASTLER-COLLER STAGE SYSTEM (MAC)

STAGE TUMOUR(T) LYMPH NODE(N) METASTASIS(M) DUKES MAC 0 Tis N0 M0 - - I T1 N0 M0 A A T2 N0 M0 A B1 IIA T3 N0 M0 B B2 IIB T4 N0 M0 B B3 IIIA T1-T2 N1 M0 C C1 IIIB T3-T4 N1 M0 C C1/C2 IIIC Any T N2 M0 C C1/C2/C3 IV Any T Any N M1 - D

(Edited from Appendix C of Textbook of Rosei and Ackerman ^,s Surgical Pathology, written by Juan Rosei, Vol 2, Ninth Ed. Pages 2811- 2812 )

THE HISTOPATHOLOGICAL GRADING OF COLORECTAL CARCINOMA The Broders^,grading system is subclassified as ¹⁰¹:

GX: Grade cannot be assessed, G1: Well differentiated,

G2: Moderately well differentiated, G3: Poor differentiated, and

G4: Undifferentiated.

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