Accelerated Partial Breast Irradiation for Early Breast Cancer

Henry Mark Kuerer, MD, PhD, FACS reviewing Strnad V et al. Lancet 2015 Oct 19. Coles CE and Yarnold JR. Lancet 2015 Oct 19.

Adjuvant APBI with multicatheter brachytherapy after breast-conserving surgery is not inferior to standard whole-breast irradiation with boost for selected patients.

Accelerated partial breast irradiation (APBI) can be delivered for breast cancer by several means and can reduce the length of treatments from a standard 3- to 6-week course to a single to 5-day course.

To compare the efficacy of APBI versus conventional whole-breast irradiation (WBI), European investigators conducted a multicenter, randomized, phase III, noninferiority trial involving 1184 breast cancer patients with stage 0 or pathologic lymph node–negative invasive tumors ≤3 cm in diameter who underwent breast-conserving surgery. Approximately 86% of patients had invasive tumors that were ≤2 cm in diameter, and 5% had ductal carcinoma in situ (DCIS). Surgical margins needed to be ≥2 mm or, with DCIS or invasive lobular cancer, ≥5 mm. APBI was delivered with multicatheter brachytherapy (total dose, 33–50 Gy delivered over approximately 4 days); the clinical target volume was ≥2 cm around the surgical site. WBI was delivered with a tumor-bed boost (total dose, approximately 60 Gy delivered over 6 weeks).

At a median follow-up of 6.6 years, the cumulative incidence of local recurrence (the primary endpoint) was similarly low with both APBI and WBI (1.44% and 0.92%, respectively), as was risk for grade 3 fibrosis at 5 years (0% and 0.2%). Additionally, no significant between-group differences were noted with respect to regional recurrences, breast cancer mortality, or second primary tumors.

Citation(s):

Strnad V et al. 5-year results of accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy versus whole-breast irradiation with boost after breast-conserving surgery for low-risk invasive and in-situ carcinoma of the female breast: A randomised, phase 3, non-inferiority trial. Lancet 2015 Oct 19; [e-pub].

Coles CE and Yarnold JR.Accelerated partial breast irradiation: The new standard? Lancet 2015 Oct 19; [e-pub].