A user's guide to evidence-based oncology

Number of patients potentially eligible for proton therapy

A group of Swedish radiation oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy in a facility where one of the principal aims is to facilitate randomized and other studies in which the advantage of protons can be shown and the magnitude of the differences compared with optimally administered conventional radiation treatment, also including intensity-modulated radiation therapy (IMRT) and brachytherapy, can be shown. The estimations have been based on current statistics of tumour incidence in Sweden, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours together with information on normal tissue complication rates. In Sweden, it is assessed that between 2200 and 2500 patients annually are eligible for proton beam therapy, and that for these patients the potential therapeutic benefit is so great as to justify the additional expense of proton therapy. This constitutes between 14-15% of all irradiated patients annually.

Randomized controlled trials in health technology assessment: overkill or overdue?

Evidence-based medicine has become a cornerstone in the development of radiation oncology and the randomized controlled phase III trial remains the gold standard for assessing differential benefits in clinical outcome between therapies. Health technologies aimed at improving treatment quality should primarily be tested using process measures or operational characteristics, the reason being that the sensitivity and specificity of clinical outcome is low for detecting quality improvements. The ongoing discussion of the relative merits of intensity modulated photon versus proton radiotherapy is used to illustrate these concepts. Concerns over clinical and individual equipoise as well as the potential limitations of health economics considerations in this setting are also discussed. Working in a technology and science based medical discipline, radiation oncology researchers need to further develop methodology for critical assessment of health technologies as a complement to randomized controlled trials.

Exploitable mechanisms for combining drugs with radiation: concepts, achievements and future directions

Widening indications for combining radiation therapy with cytotoxic or molecular-targeted drugs have mainly been driven by pragmatic clinical trials. With a flurry of novel drugs in various stages of preclinical and clinical development there is a need to revise the framework that has traditionally been used for discussing possible drug-radiation interactions, especially because many of the new drugs are directed at a specific molecular target. Spatial cooperation, cytotoxic enhancement, biological cooperation, temporal modulation and normal tissue protection are proposed as five primary exploitable mechanisms for the rational combination of drugs with radiation for cancer therapy. These five mechanisms produce different clinical outcomes and, therefore, the optimum clinical end point for assessing therapeutic benefit will depend on the mechanism tested. The dependence of outcome on these mechanisms also affects the selection of preclinical models and the optimum scheduling of the two modalities, i.e. the timing and dosing of the drug relative to the radiation dose fractions. These considerations are discussed in some detail for each mechanism and illustrated with specific clinical examples. Multi-modality therapy for head and neck squamous-cell carcinoma is used to illustrate these concepts. Further clinical progress in this field will require hypothesis-driven trials to ensure efficient identification of treatments with the most favorable risk:benefit ratio.

Does the evidence support the use of concurrent chemoradiotherapy as a standard in the management of locally advanced cancer of the cervix, especially in developing countries?

Locally advanced cancer of the cervix (FIGO stages III and IVA) is one of the most common malignancies in developing countries. Conventional treatment has been a judicious combination of external radiotherapy and intracavitary brachytherapy. However, prompted by the results of five randomised-controlled trials (RCTs) published in close succession, The National Cancer Institute (NCI) alert in 1999, and two meta-analyses, the management of cancer of the cervix has gradually changed. Concurrent chemoradiotherapy with cisplatin alone, or in combination, is gradually being favoured for the treatment of cancer of the cervix. This overview examines whether the published evidence is sufficiently adequate to justify the use of chemoradiotherapy using cisplatin as standard care in the management of cancer of the cervix, especially in developing countries, where most women present with locally advanced cancer of the cervix. A critical review of the various phase III randomised trials and meta-analyses indicates that, although chemoradiotherapy could be a standard form of treatment for early cancer of the cervix, its role in advanced stages needs further exploration before this could be incorporated into routine clinical care.

Towards evidence-based guidelines for radiotherapy infrastructure and staffing needs in Europe: the ESTRO QUARTS project

BACKGROUND AND PURPOSE

Adequate and equitable access to radiotherapy (RT) must be a reasonable health care goal for the EU. However, there are large variations among the EU countries and even regional variations within countries in the provision of RT. In this report, we combine the best available evidence on the indications for RT with national epidemiological data to arrive at estimates for the appropriate level of RT infrastructure in the 25 EU countries.

PATIENTS AND METHODS

Data from three systematic overviews of the best available evidence for the indication for RT in 23 main cancer types are combined with epidemiological data from the EUCAN and GLOBOCAN databases on the crude incidence of each of these cancers in the 25 EU countries. Together with published benchmarks for accelerator throughput this allows estimation of the number of linear accelerators per million people required to facilitate appropriate RT utilization rates in each country. Where possible, the estimates are compared with the detailed data available from Sweden.

RESULTS

The crude incidence of the main cancer types shows large variation among the 25 EU countries. This reflects in part differences in exposure to aetiological risk factors and partly differences among the countries in population age structure. Correspondingly, the estimate of the required number of linear accelerators per million people showed considerable variation: ranging from 4.0 in Cyprus to 8.1 in Hungary. The average for the 25 countries was 5.9 per million people. These estimates were compared with available national guidelines and actual data on RT infrastructure and large shortfalls were found in many countries. Implications for health economics and capacity planning are briefly discussed.

CONCLUSIONS

The QUARTS project has developed a model that establishes a direct and transparent link between epidemiological data and indications for RT based on the best available evidence. Comparison of the model estimates with current levels of RT infrastructure has revealed major inequalities in provision of RT in the 25 EU countries. Continuation of this study is recommended as a way of improving RT provision on rational grounds throughout the European community and as a model for health care planning in the EU.

High-tech in radiation oncology: should there be a ceiling?

PURPOSE

To analyze some of the limitations to improvement of the outcome of radiotherapy (RT) expected from the introduction of sophisticated treatment planning and delivery technology.

METHODS AND MATERIALS

Several recent examples from the literature were analyzed in some detail. Mathematical modeling techniques were used to assess the likely clinical impact of new technologies or biologic principles. The findings of recent randomized controlled trials of RT for prostate, breast, and rectal cancer were analyzed from the perspective of cost-effectiveness and therapeutic gain.

RESULTS

The main findings of the analyses may be summarized as follows. Dosimetric precision should aim for a <2% patient-to-patient variability in the delivered dose. Imprecision in clinical target volume definition remains an obstacle for high-precision RT. Functional imaging and novel biologic assays may facilitate a move from a clinical target volume to the real target volume. Improved target volume coverage is mainly important if RT has high effectiveness. Radiation oncology is increasingly becoming evidence based. However, there is still a long way to go. Hypofractionation in adjuvant RT for breast cancer may represent a favorable balance between cost and benefit. Treatment complications are potentially associated with both suffering and high cost. The identification of high-risk patients would improve the cost-effectiveness of high-tech RT aimed at avoiding complications. Conformal RT may allow the introduction of hypofractionation, which, again, could potentially save resources. With improvement in surgery and more screening-detected cancer cases, the number needed to treat increases, and this will directly affect the cost-effectiveness of high-tech RT unless efficient patient selection can be developed.

CONCLUSION

Sustained technological refinement is only likely to be cost-effective if the clinical and biologic understanding of patient-to-patient variability in the risk of specific types of failure and the optimal multimodality approach to handle these risks is developed at the same time. Mathematical modeling together with methods from health technology assessment and health economics are useful complements to standard methods from evidence-based medicine. Progress in functional imaging and in basic and clinical cancer biology is likely to provide the tools required for individualized risk-adapted RT.