Comparison of Acute Toxicity between Boost With MammoSite and Boost with External Photon Beam in the adjuvant radiotherapy of Breast Cancer after Lumpectomy.
To compare rates of acute Toxicity (AT) between patients treated with MammoSite Boost + Whole Breast Irradiation (WBI) with patients treated with WBI + Boost with Photon External Beam Radiotherapy (B-EBRT) at a single center.
Methods and Materials:
A total of 150 women underwent Mammosite Boost irradiation + WBI after lumpectomy and a total of 342 women underwent WBI + B-EBRT between 2011 – 2013 at our department. Included were patients who were followed up at least for 3 months. A matched-pair analysis was performed based on age, receipt of hormonal therapy, chemotherapy, nodal status, and tumor size (132 patients per arm). Rates of RTOG acute toxicities ≥ III° were then analyzed for each group.
After the match, no differences in patient characteristics were noted when tumor size was evaluated as a continuous variable. Except for a higher rate of seroma formation 55% vs. 7% p = 0.001 and radiodermatits 1% vs. 5% (p = 0.018), we observed no significant difference between 2 groups with regard of acute toxicity.
Although the rate of seroma formation is significantly higher in patients who underwent Mammosite Boost, the lower rate of radiodermatitis ≥ III° in these patients fails to confirm other retrospective claims analyses that have suggested higher rates of acute toxicity for MammoSite treatment.