A meta-analysis of data from three clinical trials, presented at the American Society of Clinical Oncology annual meeting, shows that partial breast irradiation - a shorter course of more targeted treatment than traditional radiation therapy - may offer the same benefits in terms of overall survival and reduction of metastases as conventional whole-breast radiation therapy for early-stage breast cancer. Investigators noted that several additional randomised studies are currently under way and no recommendations about this approach can be made until they are complete.

"Although more research is necessary, this study suggests that partial breast irradiation may be safe and feasible for women with early-stage breast cancer because it does not jeopardise patient survival or increase the risk of metastasis," explained lead author Dr. Antonis Valachis, associate breast cancer researcher at the Panhellenic Association for Continual Medical Research in Greece. "Partial breast irradiation reduces treatment time and radiation exposure to normal tissue, may improve cosmetic results, and is likely to enhance patients’ ability to comply with therapy."

Conventional radiation therapy is commonly used to treat early-stage breast cancer after lumpectomy and it is typically given to the whole breast five days a week for six weeks. Partial breast irradiation, which was developed in the early 1990s, is targeted only to the breast tumour area. It may be given during surgery (either through radioactive seeds or through an inserted balloon catheter) with one application, or using targeted external three dimensional conformal radiation therapy delivered over five to seven days after surgery is completed.

Dr. Valachis and his colleagues evaluated data on 1,140 women in three clinical trials comparing partial breast irradiation and traditional whole-breast radiation therapy. There were no significant differences in overall survival or the development of metastases between the two groups. However, women who received partial breast irradiation were twice as likely to experience cancer recurrence in the same breast as the primary tumor and three times more likely to develop cancer in the nearby underarm (axillary) lymph nodes. These recurrences had no affect on overall survival, however.

The researchers cautioned that partial breast irradiation will continue to be considered investigational until the results of additional, ongoing clinical trials can be analysed.