CREATING THE PLOT - CONCEPTUAL FRAMEWORKS

CONCEPTUAL FRAMEWORKS

6.4 CREATING THE PLOT

Table 11 shows a comparative analysis of the results of this study when compared with six other studies: four from the African continent and two from two other continents of the world, looking at total number of samples histologically followed up, sensitivity, inadequate rate and positive predictive values.

TABLE 1- AGE DISTRIBUTION OF THE 786 PATIENTS WITHH BENIGN BREAST SMEARS

AGE GROUP BENIGN SMEARS PERCENT

0-9 1 0.1%

10-19 82 10.4%

20-29 260 33.1%

30-39 207 26.3%

40-49 137 17.4%

50-59 62 7.9%

60-69 27 3.4%

70-79 9 1.1

90-99 1 0.1%

Total 786 100%

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TABLE 2- THE CYTOLOGICAL SUBCLASSIFICATION OF THE 607 BENIGN SMEARS.

SUBCLASSIFICATION NO. OF ASPIRATES PERCENT OF TOTAL

Fibroadenoma 197 32.4%

Fibrocystic change 121 19.9%

Inflammation 108 17.8%

Benign epithelial proliferation 100 16.5%

Lactational changes 37 6.1%

Gynaecomastia 26 4.3%

Galactocele 24 4.0%

Others 6 1.0%

Benign phyllodes tumour 3 0.5%

Benign breast cysts 3 0.5%

Intraductal papilloma 2 0.3%

Lipoma 2 0.3%

TOTAL 607 100%

Key: Others comprise the following diagnoses: Inspissated milk, Organising haematoma, Accessory breast, Involutional change, Post-irradiation and Benign lymphoid hyperplasia.

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TABLE 3- AGE DISTRIBUTIONS OF THE 426 MALIGNANT BREAST SMEARS

AGE GROUP MALIGNANT SMEARS PERCENT

10-19 4 0.9%

20-29 23 5.4%

30-39 78 18.3%

40-49 119 27.9%

50-59 108 25.4%

60-69 53 12.4%

70-79 35 8.2%

80-89 6 1.4%

Total 426 100%

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TABLE 4- THE CYTOLOGICAL SUBCLASSIFICATION OF THE 447 MALIGNANT SMEARS.

SUBCLASSIFICATION NUMBER OF ASPIRATES PERCENT OF TOTAL

Invasive ductal carcinoma 427 95.5 % (97.9%)

Mucinous carcinoma 3 0.7 % (0.7%)

Medullary carcinoma 2 0.4 % (0.5%)

Invasive papillary carcinoma 2 0.4 % (0.5%)

Intraductal carcinoma 1 0.2 % (0.2%)

Invasive lobular carcinoma 1 0.2 % (0.2%)

Burkitt’s Lymphoma 7 1.6%

Lymphoblastic Lymphoma 1 0.2%

Malignant Phyllodes Tumour 2 0.4%

Granulocytic Sarcoma 1 0.2%

TOTAL 447 100 %

Key: F: Female, M: Male, N/S: Not specified and (%): percent of carcinomas

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TABLE 5- CORRELATIONS OF CYTOLOGICAL AND HISTOLOGICAL DIAGNOSES OF THE 250 ASPIRATES THAT HAD HISTOLOGICAL DIAGNOSIS.

DIAGNOSTIC CATEGORY HISTOLOGICAL DIAGNOSIS

TOTAL BIOPSY RATE

BENIGN MALIGNANT Unsatisfactory or Inadequate

(C1)

2 3 5 13.2 %

Benign (C2) 115 8 123 15.3%

Atypia; probably benign (C3)

1 0 1 16.7 %

Suspicious of malignancy (C4)

4 21 25 23.4 %

Malignant (C5) 3 93 96 21.5 %

TOTAL 125 125 250 17.8 %

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TABLE 6- Correlations Between Cytological And Histological Diagnosis Of The 123 Benign Breast Smears That Had Biopsy.

CYTOLOGY HISTOLOGY Total

BENIGN MALIGNANT

Fibrocystic changes

Intraductal papilloma

Gynaecomastia Fibroadenoma

Lactating adenoma

Lactational changes

Sclerosis adenosis

Benign phyllodes tumour

Fat necrosis

IDC ILC IPC

Fibroadenoma 9 0 0 18 0 0 2 3 0 0 0 0 32

Fibrocystic changes

16 1 1 1 0 0 2 0 1 1 0 0 23

Inflammation 2 0 0 0 0 0 0 0 0 0 0 0 2

Benign epithelial proliferation

8 0 0 2 0 0 1 1 0 0 0 0 12

Gynaecomastia 0 0 5 0 0 0 0 0 0 0 0 0 5

Lactational changes

2 0 0 0 1 0 0 0 0 4 0 0 7

Galactocele 1 0 0 0 1 0 0 0 0 0 0 0 2

Benign phyllodes tumour

1 0 0 1 0 0 0 1 0 0 0 0 3

Benign breast cysts

1 0 0 0 0 0 0 0 0 0 0 0 1

Intraductal papilloma

1 0 0 0 0 0 0 0 0 0 0 0 1

Lipoma 1 0 0 0 0 0 0 0 0 0 0 0 1

Others 1 0 0 0 0 0 0 0 0 0 0 0 1

Not specified 18 0 1 6 0 2 0 3 0 1 1 1 33

Total 63 1 5 29 2 2 5 8 1 6 1 1 123

Key to table 6:

IDC – Invasive Ductal Carcinoma ILC – Invasive Lobular Carcinoma IPC – Invasive Papillary Carcinoma

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Table 7- Correlations Between Cytological And Histological Diagnoses Of The 96 Smears Cytologically Diagnosed As Malignant.

CYTOLOGY HISTOLOGY TOTAL

MALIGNANT BENIGN

Invasive ductal carcinoma

Invasive lobular carcinoma

Intraductal carcinoma

Osteogenic Sarcoma

Burkitt’s Lymphoma

Invasive papillary carcinoma

Medullary carcinoma

Intraductal papilloma

Fibrocystic changes

Fibrocystic changes with Moderate epithelial hyperplasia

Sub-Classification Invasive ductal carcinoma

83 3 0 1 0 1 1 1 1 1 92

Medullary carcinoma 2 0 0 0 0 0 0 0 0 0 2

Burkitt’s Lymphoma 0 0 0 0 2 0 0 0 0 0 2

TOTAL 85 3 0 1 2 1 1 1 1 1 96

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TABLE 8- THE 1401 CASES OBTAINED IN THIS CURRENT STUDY SUMMARIZED IN ACCORDANCE WITH CYTOLOGY QUALITY ASSURANCE STANDARD REPORT²³.

HISTOLOGY MALIGNANT (C5)

SUSPICIOUS OF

MALIGNANCY (C4)

ATYPIA PROBABLY BENIGN (C3)

BENIGN (C2)

INADEQUATE/

UNSATISFACTORY (C1)

TOTAL

Total malignant

93 20 0 8 3 124

Invasive 93 19 0 8 3 123

Non-invasive 0 1 0 0 0 1

Total benign 3 5 1 115 2 126

No histology 351 82 5 680 33 1151

TOTAL CYTOLOGY RESULTS

447 107 6 803 38 1401

NOTE: The tabulation is done according to the format for the calculation of cytology performance measures as shown in Table 7A of Appendix II²³.

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TABLE 9- CYTOLOGY PERFORMANCE MEASURES OF FNAC AT UCH, IBADAN OVER THE TEN YEAR PERIOD.

INDEX VALUE

Absolute sensitivity 93.5 %

Complete sensitivity 97.7 %

Specificity (biopsy cases only) 91.3 %

Specificity (full) 94.2 %

Positive predictive value (C5 diagnosis) 99.3 %

Positive predictive value (C4 diagnosis) 80.0 %

Positive predictive value (C3 diagnosis) 0.0%

Negative predictive value (C2) 99.5 %

False negative rate (this excludes inadequate results) 1.7 %

False positive rate 0.6 %

Inadequate rate for FNAC 2.7 %

Suspicious rate 8.1 %

NOTE: These are calculated as shown in Tables 10A and 11A of Appendix II²³.

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TABLE 10- COMPARISON OF PRESENT STUDY WITH SUGGESTED THRESHOLDS FOR CYTOLOGY PERFORMANCE.

PARAMETERS CURRENT STUDY (%)

MINIMUM (%)

PREFERRED (%)

CURRENT MEDIAN (%) Absolute

sensitivity

93.5 > 60 > 80 57.1

Complete sensitivity

97.7 > 80 > 90 81.5

Specificity (full) 94.2 > 55 > 65 58.5

Positive predictive value

99.3 > 98 >99 99.6

False negative rate 1.7 < 6 < 4 6.3

False positive rate 0.6 < 1 < 0.5 0.2

Inadequate rate 2.7 < 25 < 15 23.4

Suspicious rate 8.1 < 20 < 15 15.8

NOTE: These suggested thresholds are shown in Table 9A of Appendix II²³.

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TABLE 11- RESULTS REPORTED IN THE LITERATURE IN COMPARISON TO PRESENT STUDY.

PARAMETERS

Ogunniyi et al Ibadan 1989

Thomas et al Ibadan 1999

Mohammed et al Kano 2005

Bojia et al Ethiopia 2001

O’Neil et al USA 1997

Chaiwun et al Thailand 2001

Current study 2007

No. of FNAC 209 295 157 102 697 2375 1401

Biopsy rate (%) 68.9 N/S 59.2 N/S N/S 30.4 17.8

Complete

sensitivity% 79 100 90.6 94.3 97 84.4 97.7

Specificity(full)% 97 N/S 100 78.6 78 99.5 94.2

Ppv malignant% N/S N/S 100 68.8 92 99.8 99.3

Ppv suspicious% N/S N/S N/S N/S 67.2 N/S 80.0

FNR% 7.4 5 5 N/S 3.2 16.7 1.7

FPR% 1 0 0 N/S 0.7 0.5 0.6

Inadequate rate% 26.8 N/S 1.9 N/S 0.7 32 2.7

KEY:

Ppv: Positive predictive value FNR: False negative rate FPR: False positive rate N/S: Not stated.

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447

803 107 6 38

Malignant Benign Suspicious;

Probably Malignant Suspicious;

Probably Benign Unsatisfactory Figure 1 - The Diagnostic Categories Of The 1401 Cases Of Breast FNAC In The Present

Study

Not specified Female

Male

Sex

1,250

1,000

750

500

250

Frequency

Figure 2 - Sex Distribution Of The 1401 cases Of Breast FNAC

90-99 80-89 70-79 60-69 50-59 40-49 30-39 20-29 10-19 0-9

AgeGroup

400

300

200

100

Frequency

Figure 3 - Age group distribution of the 1401 cases of breast FNAC

Carcinosarcoma Sarcoma

Lymphoma Carcinoma

Histogenesis

100

Percent

0.45%

1.79%

97.32%

Figure 4 - Histogenesis (by percentage) of the 447 cases of malignant FNAC

Figure 5a - Photomicrograph of a smear incorrectly diagnosed as lactational changes in a 36 year old nursing mother showing discohesive clusters of malignant epithelial cells with marked nuclear pleomorphism and abundant vacuolated cytoplasm in a background containing neutrophil polymorphs and acellular debris. (May-Gruenwald-Giemsa stain, x40).

Figure II

Figure 5b – Photomicrograph of invasive ductal carcinoma in the same patient in figure 5a showing malignant epithelial cells invading fibrous stroma. (Haematoxylin and Eosin stain, x40).

Figure 6a - Photomicrograph of a smear categorized as suspicious; probably malignant in a 25 year old female showing few singly dispersed cells with large irregular nucleus containing large prominent nucleolus in a haemorrhagic background. (May-Gruenwald-Giemsa stain, x40).

Figure 6b – Photomicrograph of invasive lobular carcinoma in the same patient in figure 6a showing cords of malignant epithelial cells that are haphazardly invading a dense fibrous stroma.

(Haematoxylin and Eosin stain x40).

CHAPTER FIVE DISCUSSION

In this retrospective study, 1401 breast aspirates were evaluated. Out of this figure, 38 (2.7%) were categorized as unsatisfactory (C1). In similar study, Shehu et al⁵¹ in Zaria and Mohammed et al⁵⁴in Kano reported unsatisfactory rates of 3.7% and 1.9%

respectively. These percentages sharply contrast with earlier report in Ibadan, where Ogunniyi et al⁴⁹ reported an unsatisfactory rate of 26.8%. This marked difference could be attributed to the fact that Pathologists are the aspirators in Zaria, Kano and currently in Ibadan instead of Clinicians as was the case before the establishment of FNAC clinic in the pathology department^16,54.

The majority of the breast aspirates (57.3%) were categorized benign (C2).

This study shows that most patients that had breast FNAC were females: 97.0% as against 2.8% in males. This is in keeping with Baum’s² findings.

This study also shows that the age range of patients with breast FNAC was from 7 to 91 years with a mean age of 39.5 years.

Fibroadenoma was the most frequent (32.4%) cytologically diagnosed benign breast lesion.

In this study, the mean age of diagnosis of fibroadenoma was 25 years.

Fibrocystic change was the second commonest (19.9%) cytologically diagnosed benign lesion.

In this study, the mean age of diagnosis of fibrocystic change was 40 years.

Gynaecomastia was the commonest (66.6%) breast lesion in male with the age range of 7 to 70 years and a mean age of 35 years. This condition is associated with imbalance between oeatrogens (which stimulate breast tissue) and androgens which counteract this effect. There was no association with Klinefelter’s syndrome or a functioning testicular neoplasm.

In this study breast cancer increased with reproductive age and peaked in 5^th decade of

In this study, carcinomas were the commonest malignant smears and accounted for 97.3% of all the malignant smears. The overwhelming majority (97.9%) of the carcinomas were subtyped as invasive ductal carcinoma. This finding is similar with what was reported by Kline et al²⁶.

All the male malignant smears were subtyped invasive ductal carcinoma with age range of 55 to 75 years.

Burkitt’s lymphoma is the most frequently (63.6%) diagnosed non–carcinomatous malignant smears with the age range of 13 to 39 years and mean age at diagnosis of 22 years.

International studies have demonstrated good correlation between FNAC and histology Theresults⁵⁴. Obtaining a preoperative diagnosis is desirable when dealing with breast cancer as it gives the patient a chance to come to terms with a diagnosis of cancer prior to surgery and allows discussion of treatment options in order to progress to a therapeutic rather than a diagnostic operation. Also reduces the benign surgical rate avoiding unnecessary surgery in women with benign lesions especially in areas where resources are limited²³.

In this study, pathologists were able to correctly interpret as benign 93.5% of patients with breast lesions evaluated cytologically as benign. In a similar study, Ogunniyi et al⁴⁹, Shehu et al⁵¹ and Mohammed et al⁵⁴ reported 95%, 100% and 97% respectively.

The reasons for this relatively slightly lower percent in this current study may be due to the larger sample size of 123 obtained in this current study as compared to sample sizes of 67, 49 and 60 evaluated by Ogunniyi⁴⁹, Shehu⁵¹ and Mohammed⁵⁴ respectively.

Fifty percent of the false negative cases were cytologically interpreted as lactational changes. Six The reason no doubmayt be due to the usual extreme caution exercised by most pathologists in making diagnosis of cancer, cytologically, in pregnant or lactating women with palpable breast diseases^60,61.

In this study, 100%, 69.6% and 56.2% of gynaecomastia, fibrocystic change and fibroadenoma, respectively, were correctly subclassified cytologically.

In this study, pathologists were able to correctly interpret as malignant 96.9% of patients with breast lesions evaluated cytologically as malignant. In similar study, Ogunniyi et al⁴⁹, Shehu et al⁵¹ and Mohammed et al⁵⁴ obtained 97.6%, 100% and 100% respectively in their studies. The reasons for this relatively slightly lower percent in this current study may be due to the larger sample size of 96 obtained in this current study as compared to sample sizes of 41, 48 and 27 evaluated by Ogunniyi⁴⁹, Shehu⁵¹ and Mohammed⁵⁴ respectively.

In this study, there were only 3 false positive cases that were histological diagnosed as intraductal papilloma, fibrocystic changes and fibrocystic changes with moderate epithelial hyperplasia respectively.

In this current study, 3.3% of the aspirates cytologically diagnosed as invasive ductal carcinoma turn out to be invasive lobular carcinoma. Problems in differentiating lobular from ductal carcinoma are attributed to the morphologic spectrum of lobular carcinoma cells including pleomorphic lobular carcinoma, and to the overlap of cytological features between ductal and lobular carcinoma²⁶.

Although there are few series in the literature describing FNAC of medullary carcinoma of the breast, this lesion is reported to have characteristic features and is easily interpreted as malignant and as medullary carcinnma²⁶. Medullary carcinoma has been reported to have the highest percentage of positive results of those carcinomas diagnosed cytologically⁵⁵. However, this current study does not support this observation since 1.1% of the aspirates cytologically diagnosed as invasive ductal carcinoma proved to be medullary carcinoma and 100% of the aspirates cytologically diagnosed as medullary carcinoma proved to be invasive ductal carcinoma.

In this current study 1.1% of the aspirates diagnosed as invasive ductal carcinoma proved to be mucinous carcinoma.

Thus, this current study shows that though ductal carcinoma can be easy to discern in cytology, the cytomorphological differences between it, invasive lobular carcinoma, mucinous carcinoma, medullary carcinoma, and invasive papillary carcinoma are still quite difficult.

The absolute and complete sensitivity of 93.1% and 97.4% respectively obtained in this study are significantly above the lower limits of preferred standards for quality assurance required suggested by the United Kingdom National Health Services Breast Screening Programme (NHSBSP) (which are > 80% and > 90% respectively)²³ as

The reasons for this is likely due to non-inclusion of impalpable breast lesions in in UCHthis study, Ibadan and also due to the fact that most of our patients with malignancy present with advanced tumours thereby minimizing sampling error^{87, 8*, *}

*, * as evidenced by an inadequate rate of 2.7% obtained in this current study as against the suggested preferred minimum and current median rates of <25% and 23.4% respectively. The positive predictive value for malignancy of 99.3% obtained in this current study is above the suggested minimum value of >98%²³and compares favourably with those obtained previously in Ibadan, Kano and Thailand that are were 100%⁵⁶, 100%⁵⁴ and 99.8%⁵³ respectively, but it is significantly higher than the sensitivity of 79%⁴⁹ obtained in Ibadan 18 years ago - most likely due to the significant reduction in the unsatisfactory rate in this current study.

The specificity (full) of 94.4% obtained in this study is significantly well above the lower limits of the corresponding preferred standards for quality assurance required by the NHSBSP³⁶ NHSBSP (which is > 65%)²³ as well as the current world median value of 57.1%²³. This current value of 94.4% is slightly lower than those obtained in previously in Ibadan, Kano, and Thailand, which were 97%⁴⁹, 100%^* %⁵⁴ and 99.5%^*

%⁵³ despite having comparable similar low false positive rate (0.6%). This may be due to differences in statistical analysis.

False positivity is one of the most worrying aspects of breast FNAC as mastectomy could be done for a benign lesion with serious clinical and medico-legal implications¹⁴. The current false positive rate of 0.6% obtained in this current study is well within the recommended <1%⁴⁸, and is intermediate to the rates of 1%⁴⁹ and 0%⁵⁶ previously obtained in this centre eighteen and eight years ago respectively. In addition, it compares favourably with thoseat in United States of America and Thailand, which were 0.7%^50* and 0.5%^53* respectively. It has been shown that false positive fine needle smears often occur with peculiar types of breast lesions such as intraductal papilloma, fat necrosis, tubular adenomas, pregnancy- or radiation- related changes and granulomas^18*,*. In this current study, the three false positive aspirates were intraductal papilloma, fibrocystic changes, and fibrocystic changes with moderate epithelial hyperplasia respectively.

False negative diagnosis is another area of concern. Even in the most experienced centres, 10% of cancers have a false negative cytology^*. ⁴⁹. This is reflected in the current median false negative rate of 6.3%³⁶²³. It is said to be more commonly

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