WESTPORT, Mar 14 (Reuters Health) - Locoregional radiation improves survival in women who undergo surgery and traditional chemotherapy for breast cancer, according to meta-analysis results published in the March issue of the Journal of Clinical Oncology.
Radiation has been shown to prevent cancer from recurring, but most studies have not indicated that it actually improves survival, Dr. Timothy J. Whelan, of the Hamilton Regional Cancer Centre in Ontario, Canada, pointed out in an interview with Reuters Health. However, "there were several recent studies that have shown a bit of a survival benefit," he added. "People wondered how to interpret these studies."
In an attempt to resolve the issue, Dr. Whelan's team reviewed 18 trials that collectively included 6,367 patients. The studies began between 1973 and 1984. Most of them involved both pre- and postmenopausal women who underwent modified radical mastectomy for node-positive breast cancer. All participants received systemic therapy, most often with cyclophosphamide, methotrexate, and fluorouracil.
Overall, radiation resulted in a 31% reduction in the risk of recurrence, largely due to a 75% reduction in the risk of local recurrence, the researchers report.
The results of the meta-analysis also indicated that locoregional radiation was associated with a 17% reduction in mortality. In six of the nine studies that included more than 200 patients, the treatment effect was positive.
Although these results are consistent with those of three recent studies, they differ from those of previous meta-analyses, Dr. Whelan and colleagues note. Most likely, they say, the discrepancy is due to the fact that the current analysis included only patients treated with systemic therapy and included studies with long follow-up periods, which were not available for previous analysis.
"Our results support the notion that, in the presence of adjuvant systemic therapy, local regional control is important and that reduction in locoregional recurrence may prevent secondary systemic spread from regional sites and, thus, prolong survival," the researchers conclude.
In the interview with Reuters Health, Dr. Whelan noted that breast cancer treatment has undergone major changes in the 15 to 25 years since most of the studies included in the meta-analysis began. "This study suggests that the proof of principle is there, but it's difficult to make practice recommendations," he said.
J Clin Oncol 2000;18:1220-1229.