Accelerated partial breast irradiation (APBI) is more effective in preventing local breast cancer recurrence than whole breast irradiation (WBI), according to a study presented at the American Society of Breast Surgeons (ASBrS) annual meeting in Phoenix, May 2-6.
Researchers shared data from the ASBrS MammoSite Registry Trial, which comprised 1,449 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 percent with ductal carcinoma in situ (DCIS), with a median follow-up of 60 months.
In the ASBrS study, 3.5 percent of patients treated with brachytherapy developed an ipsilateral breast tumor recurrence (IBTR), 14 at the initial tumor site and 36 elsewhere in the breast.
“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,” said Peter D. Beitsch, MD, director of the Dallas Breast Center and co-principal investigator for the ASBrS MammoSite Registry.
“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.” Beitsch suggested that the elsewhere recurrence rate reflected the baseline of such recurrences.
The findings of the ASBrS study stand in contrast with a study published May 2 in the Journal of the American Medical Association (JAMA), which compared APBI to WBI and linked APBI with increased morbidities. Beitsch contradicted the JAMA study, stating, “We radiate the breast to control undetectable cancer cells left behind around the lumpectomy cavity. Common sense would say internally targeted radiation would be the best method to kill these cells. We now have strong data to support that, and that the complication rate is very low from this form of therapy.”