After over forty years of experience with radiation for breast cancer, investigators are once again reviewing safety data. Radiotherapy techniques continue to improve, in that radiation to adjacent heart and lung tissue can be reduced with newer equipment and more sophisticated treatment algorithms. In a recent Journal of Clinical Oncology, Taylor and colleagues from Oxford have done a huge meta analysis of numerous studies to try to get a handle on the risk/benefit ratio of radiation for breast cancer. Click here for the abstract; Dr. Stark can send you the entire article as a PDF if you request it on the form to the right. The authors looked at the results in over 40,000 women in various trials all of which involved randomization to radiation versus no radiation. What they found should not be surprising. There was increased risk of a second cancer in women irradiated. Most of these were lung cancers and contralateral breast cancers; some were esophageal. The lung cancer risk peaked more than ten years after breast cancer. As for breast cancer, there were about 25% more second breast cancers in the radiation group, but the number in the control group was still substantial — part of the natural history of breast cancer. The authors comment that with better radiation techniques this disparity will likely go away. There was a marked increase in death from heart disease in the irradiated group — including valvular heart disease, a finding also seen after radiation for Hodgkin Lymphoma. Virtually all of the excess mortality from lung cancer and heart disease could be accounted for in the group of women who smoked. Among non-smokers the increased risk was negligible. The authors editorialize that smoking cessation at the time of breast cancer diagnosis should be helpful in this regard.
Dr. Stark comments: If you don’t smoke there is benefit to radiation for breast cancer. That much is clear. The authors postulate that smoking cessation at breast cancer diagnosis will negate the risk of second cancer and heart disease from radiation. They ignore, however, data from Doll and Peto, the best in the business, that state that while smoking cessation is helpful, it only keeps the cancer risk from increasing, that there is no real risk reduction. It is unlikely that this important study will dissuade women or their doctors from using radiation in smokers, but the increased risks are sobering.