Re: Comparative effectiveness of radical prostatectomy and radiotherapy in prostate cancer: observational study of mortality outcomes
Sooriakumaran et al conclude that surgery is better than radiotherapy for non- metastatic prostate cancer and that radiotherapy is equally good for metastatic prostate cancer patients. We are concerned that a glaring oversight in peer review process has failed to pick up significant flaws in the paper.
Radical radiotherapy or prostatectomy is not an option for patients who present with metastatic cancer and there is no way of knowing beforehand which patients will eventually develop metastatic disease many years after radical treatment. Hence, the statistical conclusions about metastatic cancer patients are nonsensical.
As regards non-metastatic cancer patients, there has been a critical flaw in patient selection with exclusion of patients on hormone therapy. The authors acknowledge most radiotherapy patients had higher risk disease than surgical patients. Since publication of RTOG studies and EORTC randomised trials in late 1990s, radiotherapy in combination with hormone therapy has become the international standard of care for high risk patients.. Hence all high risk patients are commenced on hormone therapy, quite often before starting radiotherapy. So the study exclusion of patients on hormone therapy would have excluded patients who had optimal therapy and included patients who had inferior monotherapy.
Furthermore, urological surgeons, as gatekeepers of prostate patients, refer only surgically poor candidates. (either due to medical comorbidity or aggressive cancers) for radiotherapy. The statistical tests cannot fully compensate for this critical surgical referral bias. For instance, Charlson comorbidity score does not adequately address the severity of each comorbidity and it is a well known fact that more severe any particular comorbidity is, the less likely a surgeon would embark on prostatectomy. Since surgery is not a realistic option for a majority of these high risk cancer patients, the statistical conclusion that surgery is a better option is not a clinically valid conclusion.
1 Sooriakumaran P, Nyberg T, Akre O, et al. Comparative effectiveness of radical prostatectomy and radiotherapy in prostate cancer: observational study of mortality outcomes. BMJ 2014;348:g1502.
2 Bolla M, Gonzalez D, Warde P, et al. Improved survival in patients with locally advanced prostate cancer treated with radiotherapy and goserelin. N Engl J Med 1997;337:295–300. doi:10.1056/NEJM199707313370502
3 Pilepich MV, Caplan R, Byhardt RW, et al. Phase III trial of androgen suppression using goserelin in unfavorable-prognosis carcinoma of the prostate treated with definitive radiotherapy: report of Radiation Therapy Oncology Group Protocol 85-31. J Clin Oncol Off J Am Soc Clin Oncol 1997;15:1013–21.
Competing interests: No competing interests