A recent meta-analysis confirms that adjuvant radiation after breast cancer surgery improves disease-specific survival, in addition to preventing recurrences.
The analysis, conducted by the Early Breast Cancer Trialists' Collaborative Group, appears in The Lancet (2005;366:2087–2106). It included data on 42,000 women who took part in 78 randomized trials comparing different adjuvant treatment approaches: radiotherapy versus no radiotherapy, more versus less surgery with and without radiotherapy, and more surgery versus radiotherapy.
The analysis showed that for every four local recurrences prevented by radiation, approximately one breast cancer death could be prevented over 15 years.
“I believe what this paper does is confirm and add to the data that prevention of a local recurrence can improve your chances of surviving breast cancer,” said Christy Russell, MD, Chair of the ACS's Breast Cancer Advisory Group and Codirector of the University of Southern California Norris Breast Center. She was not involved in the research.
Among the 7,300 women treated with breast-conserving surgery (BCS), radiotherapy reduced the 5-year local recurrence risk from 26% to 7%. The risk of 15-year breast cancer mortality decreased from 35.9% to 30.5% (2p = 0.0002).
For the 8,500 women who had a mastectomy, radiotherapy reduced the 5-year risk of local recurrence from 23% to 6%, and reduced the 15-year risk of death from breast cancer from 60.1% to 54.7% (2p = 0.0002).
Radiotherapy also significantly improved overall 15-year survival, regardless of which operation was performed.
The proportional reduction in local recurrence and disease-specific mortality was unaffected by tumor characteristics. However, the absolute reductions in both outcomes were greater among women with positive nodes, larger tumors, and higher-grade tumors.
Adjuvant radiation is standard treatment for most women who choose BCS, and Russell said the meta-analysis significantly confirms this approach.
“These data help strengthen the argument that there is a substantial benefit to post-BCS radiotherapy and that it should be a rare patient with a very low risk of recurrence or a very short expected life span for whom it should be eliminated,” she said. “In addition, we are all looking for the correct patient population for whom postmastectomy radiation is indicated, and this meta-analysis spells out the benefits and risks in that circumstance as well.”
Russell said medical oncologists can use the data in this new analysis to help their patients make decisions about whether to seek adjuvant radiotherapy. She cautions, though, that the large benefits seen in this analysis may be less in current patients.
“Current hormone therapies and chemotherapy regimens are better in reducing local recurrence than those that were used in the clinical trials presented,” she explained. “Both those therapies, if used, may make the benefit of radiation therapy less significant with regards to both local recurrence and breast cancer-specific survival.”