Radiotherapy treatment for breast cancer only reduces the risk of cancer returning for ten years, having no effect thereafter, according to research from the University of Edinburgh.
The findings come as a result of one of the longest and most up-to-date follow-ups of randomised controlled clinical trials of breast-conserving therapy. This unique research will provide important information for long-term survivors of breast cancer and doctors.
“Long-term follow-up is essential in breast cancer trials so that we can understand the full picture. These data challenge the idea that radiotherapy improves long-term survival by preventing recurrences of cancer in the same breast,” said Ian Kunkler, Honorary Professor of Clinical Oncology at the University of Edinburgh.
The study followed 585 patients aged 70 or younger who had been diagnosed with early breast cancer. Each participant was studied for 30 years. The patients were treated with breast-conserving surgery followed by systemic therapy, including chemotherapy or the drug tamoxifen. Each patient was assigned a different treatment based on whether their cancer was driven by the hormone, oestrogen. They were also randomised to receive or not to receive radiotherapy treatment after surgery.
Radiotherapy treatment had no effect after 30 years
Recurrence of cancer in the same breast was significantly reduced by more than 60% in the group who received radiotherapy treatment in the ten-year period following the procedure. However, after the first ten years, the annual risk of a cancer recurrence and overall survival was similar for both groups. After 30 years, 24% of women who underwent radiotherapy treatment were still alive compared to 27.5% of those who did not.
“We found that there is no long-term improvement in overall survival for those women having radiotherapy. This may be because, although radiotherapy may help to prevent some breast cancer deaths, it may also cause a few more deaths, particularly a long time after the radiotherapy, from other causes such as heart and blood vessel diseases,” said Kunkler.
“The benefits of having radiotherapy in terms of fewer local recurrences are only accrued over the first ten years after radiotherapy; thereafter, the rate of local recurrence is similar whether or not patients had radiotherapy,” he added.
Researchers encourage a rethink of long-term cancer treatments
The findings of this study have drawn comparisons to other similar studies with long-term follow-up. The follow-up of randomised breast cancer trials after ten years has often been restricted by a shortage of resources. The researchers have called for increased funding to support the collection of long-term outcome data. The researchers believe their findings show that such data can challenge traditional concepts of long-term anti-cancer benefits of radiotherapy treatment.
“It’s important to note that every woman with breast cancer is different and will have different forms of the disease. Decisions about whether or not to have radiotherapy after surgery should be taken by patients and their doctors after careful discussion, taking into account the individual characteristics of their breast cancer and the likely risks of recurrence over the long term, both within and outside the breast, and of treatment-related toxicity,” said Kunkler.