MedicalResearch.com Interview with:
Robert Nam, MD, FRCSC
Ajmera Family Chair in Urologic Oncology
Professor of Surgery
University of Toronto
Head, Genitourinary Cancer Site
Odette Cancer Centre
Sunnybrook Health Sciences Centre
MedicalResearch.com: What is the background for this study?
Response: Prostate cancer treatment is associated with a number of complications including erectile dysfunction and urinary incontinence. Two years ago, we published a paper examining other, previously undescribed complications. The most controversial finding was a significantly increased risk of secondary cancers among men treated with radiotherapy. We therefore wanted to assess this in a meta-analysis, examining all the research currently available on the topic.
MedicalResearch.com: What are the main findings?
Response: We found that, for patients with prostate cancer, radiotherapy treatment was associated with significantly increased rates of bladder cancer, colorectal cancer and rectal cancer. There wasn’t an increased risk for other cancers such as lung and blood system cancer. However, the absolute rates of these cancers remained low (1-4% of patients).
MedicalResearch.com: What should clinicians and patients take away from your report?
Response: We feel that the risk of secondary cancers, given its severity, is a complication which must be discussed prior to deciding on prostate cancer treatment particularly for patients who need treatment (that is not watchful waiting) and where treatment is effective with long survival/cure. Patients must weigh for themselves the various risks and benefits of each treatment option.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: The currently available studies lack important information on other factors that may contribute to the development of secondary cancers. For example, data is not routinely collected on smoking status which may be associated with secondary cancers. While we can be somewhat reassured that smoking did not significantly affect the findings, due to the lack of association between radiotherapy and lung cancer, future research using prospectively maintained cancer registries, rather than administrative data, may be able to better assess this.
Further, future research to assess the mechanisms of radiation-induced secondary cancers and whether there are biologic markers which may indicate that a patient is at greater risk of developing a secondary cancer could help to improve treatment for patients with prostate cancer.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Wallis Christopher J D, Mahar Alyson L, ChooRichard, Herschorn Sender, Kodama Ronald T,Shah Prakesh S et al. Second malignancies after radiotherapy for prostate cancer: systematic review and meta-analysis BMJ 2016; 352 :i851
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Robert Nam, MD, FRCSC (2016). Prostate Cancer Radiation Raises Risk of Colon and Bladder Cancers