Limitations of the case study approach

No one can doubt that the clinical introduction of IMRT more than ten years ago has provided major benefits to patients. Anyone who has compared the uncertainties of 2-D radiotherapy to 3-D CRT and to IMRT can see how much progress has been made. However, this progress has been difficult to document in published research. This may be because of the difficulty of reflecting in publications the subjective changes in treatment quality and patient quality of life. Or perhaps because too many started too early, using an immature technology, swayed by the potential clinical (or economic) benefits, prescribing IMRT for cancers or anatomical sites that did not require or benefit from it, the actual outcomes were blurred. The implementation speed of IMRT in the United States of America was (or still is) completely different than in Europe, where the average use is lower.

An interesting question that should be answered is: What is IMRT? There

in the same axes [10.9]. Class solutions or geometrical solutions used to treat almost all patients in a given anatomical region (e.g. prostate cancer) would not qualify as IMRT using the inverse planning requirement. In an attempt to find the best way to treat prostate cancer, a comparison of different available approaches and methods has been published. Using the same data set, a total of 34 different techniques and planning systems were evaluated; the four best ranked plans all involved forward planning IMRT [10.23].

Peters et al. [10.24] reported on the clinical impact of QC and protocol compliance in patients with advanced head and neck cancers treated in the TROG 02.02 trial. They showed that noncompliance with the radiotherapy plans had a major negative impact on the treatment results. The patient group with the compliant plans had a two year overall survival rate of 70%, compared with 50%

for those patients with major deviations from the requested radiotherapy. This trial enrolled over 818 patients in 81 different centres, and the treatment was either standard head and neck radiotherapy or forward planning 3-D CRT, but no IMRT treatments were included. The authors also showed that the centres enrolling more patients (over 20) had a better compliance rate than those centres enrolling fewer than five patients. Interestingly, the authors concluded that the effect of a good radiotherapy technique overrides the effect of the added chemotherapy drugs, which in many cases add an important economic burden to the treatment.

Although one could argue that the IMRT techniques for head and neck cancers could overcome the technical problems, the lack of significant improvement in overall survival and quality of life in head and neck cancer patients treated with IMRT could be explained by a similar ‘non-compliance’ effect.

Prostate cancer has progressed from being a ‘radioresistant’ tumour to a radiosensitive one in recent decades. The impact of dose escalation has been proved, and the quest to deliver even higher doses to the prostate gland continues.

There is still no ‘winning’ treatment in the race between urologists and radiation oncologists for local control. Both groups have achieved comparable rates of biochemical (PSA) disease free patients at five or more years of follow-up despite the T stage.

Why is this? If we consider that a cancer can only be cured if all cancer clonogenic cells are eradicated, then the logical explanation is that we are not eliminating all these clonogenic cells with our current techniques. An important clonogenic cell hiding place is the lymph nodes, and this might be the reason why we cannot achieve better disease control. An important proportion of prostate sentinel lymph nodes are located outside the obturator and external iliac regions, thus not following an expected drainage pattern [10.25]. These regions are often not included in standard radiotherapy fields.

While better technology is available, and while it is ideal to be able to use it to benefit patients, completely new hazards are emerging with it. The New York

Times reported a radiotherapy accident that occurred in New York in relation to the use of these new technologies [10.26, 10.27].

There is a debate [10.28] regarding the issue of informatics in radiotherapy.

Computerized treatment planning is an important field that provides significant benefits, but it can also be a source of great difficulties. Vendors often upgrade computer planning and operating systems, and sometimes the new releases do not allow previously installed programs, or parts of them, to run as expected.

Modern radiotherapy departments are often part of a hospital network, sharing useful information, but also computer viruses. Many medical software vendors do not recommend the use of networks, but this is hardly practical in this day and age. Who is, or should be, responsible for the RVS software, networks and computers in a radiation oncology department?

On the other hand, the knowledge acquired from implementing these complex techniques has expanded the possibilities of 3-D CRT, making more challenging treatments feasible. TPS software and algorithms are more precise than in the past. Different image modality integration in the TPS for a more precise contouring of target volumes and the now better known dose tolerances to OAR facilitate a more robust and accurate 3-D CRT. The better and faster MLCs, with good QA programmes, allow more accurate shielding of healthy organs. Implementation of RVS software to connect the TPS with, and to control, the linacs also facilitates the use of more beams and treatment techniques, which would not be possible without this computerized control. In many cases, the use of the electron beam is no longer required to protect OAR (in head and neck or breast cancer), allowing the treatment of more cases in less expensive single energy linacs.

IGRT also has improved the aiming ability, which, together with a better understanding of different diseases, permits higher dose schemes to be prescribed. Today, IMRT treatment should probably not be started without the pertinent IGRT capabilities [10.21]. This does not mean that IMRT treatment can only be conducted with the aid of a cone beam CT system or similar system.

Head and neck IMRT can be conducted using portal imaging and by referring to the bony anatomy, and the prostate can be treated with portals and fiducial markers or other methods, but a regular, and in most cases daily, position control of the target before treatment should be required for IMRT.

There is no doubt that modern technologies such as IMRT and IGRT have brought radiation oncology to a higher level, but we should be aware that there are very important issues to be resolved [10.6]. The IAEA has issued a publication to assist centres in moving along the path from 2-D radiotherapy to

each State to implement the needed controls and rules in order to ensure that the radiotherapy centres are complying with the recommendations of international bodies, including the IAEA, ensuring that patients are receiving high quality therapy.

Better imaging, better understanding of disease through cancer biology and radiobiology, and more robust and reproducible treatment techniques are of paramount importance if we are to achieve better cancer control by radiation.

It is our responsibility to offer our patients the best, not the fanciest, treatment available.