The rate of long-term complications such as palpable masses and telangiectasias was nearly five times higher in women who had MammoSite therapy, compared with those who underwent whole breast radiation therapy, results from a retrospective study showed.
Dr. Kari Rosenkranz and her associates at Dartmouth Hitchcock Medical Center, Hanover, N.H., analyzed the data charts of all women who met criteria for brachytherapy and underwent MammoSite (n = 71) or whole breast radiation therapy (WBRT) (n = 245) at the center between 2003 and 2008.
Dr. Kari Rosenkranz
The incidence of palpable masses at the site of the lumpectomy, telangiectasias, and local recurrence were the studied endpoints. No significant differences existed between the study groups regarding age (average was 63.5 years), mean size of tumor (average was 1.1 cm), the percentage of patients with estrogen receptor–positive tumors (92% in total), or the length of follow-up (median was 4 years).
In the MammoSite cohort with hormone receptor–positive tumors, 83% received adjuvant endocrine therapy; 94% of the WBRT group with hormone receptor–positive tumors had endocrine therapy. No significant difference was found in systemic chemotherapy rates.
The rate of long-term complications such as palpable masses, telangiectasias, or both were found to have occurred in 42% of MammoSite patients, compared with 9% in the WBRT group (J. Am. Coll. Surg. 2013;217:497-502).
During follow-up in the MammoSite group, the incidence rate of palpable mass detection at the lumpectomy site was nearly 27%; for the WBRT group, the rate was approximately 7%. MammoSite patients were three times more likely to require a core biopsy of the mass to rule out malignancy than were WBRT patients (16.9% vs. 4.9%, respectively). Telangiectasia was six times more likely to develop in MammoSite patients than in WBRT patients (24% vs. 4%).
Dr. Rosenkranz and her colleagues reported that a prospective, randomized clinical trial which began in 2005, sponsored by the National Surgical Adjuvant Breast and Bowel Project (NSABP)/Radiation Therapy Oncology Group (RTOG), is currently underway to compare WBRT with partial radiation therapies such as MammoSite. The primary endpoint of this study in women who have had surgery for ductal carcinoma in situ or stage I or stage II breast cancer, is breast tumor recurrence; secondary endpoints include toxicity. The study is expected to end in 2015, according to the researchers.
"Until this prospective, randomized trial reports, the increased rate of long-term local toxicity found in our institution’s experience with MammoSite brachytherapy should be considered when counseling women on options for adjuvant radiation therapy after breast-conserving surgery," concluded Dr. Rosenkranz and her associates.
The researchers reported no relevant disclosures.