Outcomes for APBI with strut-based brachytherapy: First 100 accrued patients (5-year median follow-up).

Abstract

114 Background: The SAVI Collaborative Research Group (SCRG), was created to study the long-term outcomes of women receiving accelerated partial breast irradiation (APBI) using strut-based applicators. The outcomes for the first 100 accrued patients in the study are reported. Methods: Patients for this subset analysis weretaken as the initial 100 treated across all participating sites. Median follow-up of this cohort was 56.3 months at the time of the abstract. Patients were treated with APBI using the strut-based brachytherapy device with conventional dose and fractionation (3.4 Gy x 10 fx, BID). Treatment planning goals for the planning target volume were a V90>90%, V150<50 cc, and V200<20 cc. Patients were followed regularly by their radiation oncologist and outcomes were graded based on the CTCAE v3.0 (common terminology criteria for adverse events, version 3.0). Recurrence (raw and actuarial) rates were also calculated based on the follow up. Cosmesis was graded using the Harvard Scale. Results: 75 patients had invasive disease and 25 had ductal carcinoma in situ. The median age was 60.5 yrs (range 40-85 yrs), with 84% post-menopausal. Median tumor size was 10.0 mm (range 0.7-35 mm) with 92% being estrogen receptor positive. 65% of patients had at least one round of hormone therapy and 7% had chemotherapy. All patients completed APBI as planned with no serious adverse events. All patients met the dosimetric criteria. Good/excellent cosmesis was seen in >94% of subjects at all times of follow up (6-60 months). The 5-yr actuarial rates for TR/MM were 2.2%, 1.5% and 4.2% for all subjects, invasive and DCIS subgroups, respectively. The 5-yr actuarial rates for IBTR were 3.3%, 3.0% and 4.2% for all subjects, invasive and DCIS subgroups, respectively. Conclusions: For these initially treated 100 patients with a median 5 years of follow up, strut-based brachytherapy appears to be a well-tolerated, effective treatment with low rates of toxicities and local control as good as other brachytherapy APBI methods.