APBI, WBI equally effective in preventing local breast cancer recurrence

Accelerated Partial Breast Irradiation (APBI) also known as brachytherapy, is equally effective--if not more effective-- in preventing local breast cancer recurrence than Whole Breast Irradiation (WBI), according to a study to be presented this week at the American Society of Breast Surgeons (ASBrS) Annual Meeting. Brachytherapy treats only the lumpectomy site, while WBI treats the entire breast. The findings of the ASBrS study contrast with a study from the University of Texas MD Anderson Cancer Center appearing in the May issue of the Journal of the American Medical Association (JAMA).    

Researchers will report on data from the ASBrS MammoSite Registry Trial comprising 1449 breast cancer patients treated with APBI brachytherapy at 97 institutions between May 2002 and July 2004. Eighty-seven percent of these patients were diagnosed with invasive breast cancer and 13% with DCIS, with a median follow up of 60 months.

In the ASBrS study, 50 patients treated with brachytherapy (3.5%) developed an ipsilateral breast tumor recurrence (IBTR), 14 (1.1%) at the initial tumor site and 36 (2.6%) elsewhere in the breast. For invasive cancers, IBTR was associated with estrogen receptor (ER) negative disease. For DCIS, IBTR was associated with age <50 or close/positive surgical margins.

"Prior studies have demonstrated that the risk of cancer recurrence in the conserved breast is similar for WBI or APBI. Following WBI, most breast recurrences are at the initial tumor site, and relatively few are elsewhere in the breast," says Dr. Peter Beitsch, Director of the Dallas Breast Center, Co-Principal Investigator for the ASBrS MammoSite Registry and lead author on the ASBrS study. "This study demonstrated that for patients treated with APBI, this ratio was reversed: most breast recurrences were elsewhere in the breast and only a minority were at the initial tumor site. These data suggest that although tumor control in the breast appears to be similar for APBI and WBI, disease control at the initial tumor site may be better with APBI."