S2-1: Partial Breast Brachytherapy Is Associated with Inferior Effectiveness and Increased Toxicity Compared with Whole Breast Irradiation in Older Patients.

Abstract

Background: Accelerated partial breast brachytherapy (APBI-brachy) is an increasingly popular radiation treatment for older patients diagnosed with early stage breast cancer. Despite growing utilization, there is a lack of population-based cohort studies as well as randomized phase III data to compare its effectiveness and toxicity profile with standard whole breast irradiation (WBI). The purpose of this study was to provide the first nationally comprehensive comparison of effectiveness and toxicity outcomes in older Medicare patients treated with APBI-brachy versus WBI. Methods: Medicare billing claims identified beneficiaries age>66 with incident invasive breast cancers diagnosed between 2000 and 2007 and treated with conservative surgery followed by APBI-brachy alone versus WBI. Cumulative incidence of subsequent mastectomy (a validated surrogate for local failure) was compared between the two treatment groups using the log-rank test. Adjusted risk of subsequent mastectomy was determined using a multivariate Cox proportional hazards model including demographic, socioeconomic, and clinical covariates. Risks of acute complications (hospitalization or infection within 120 days of radiation), were compared using the chi-square test. Adjusted odds of acute complications were determined using multivariate logistic models including covariates. Cumulative incidences of long-term toxicities (rib fracture, fat necrosis, breast pain, and pneumonitis) were compared using the log-rank test. Results: In 130,535 women, use of APBI-brachy increased over time from <1% of patients treated in 2000 to 13% of patients in 2007 (P<0.001 for trend). Patients treated with APBI-brachy were less likely to have axillary lymph node involvement or to have received chemotherapy, and were more likely to be older, White, and have comorbid illness. At 5 years, the cumulative incidence of subsequent mastectomy was significantly higher in patients treated with APBI-brachy (4.0% in APBI-brachy vs. 2.2% in WBI, P<0.001). On multivariate analysis, there was a two-fold increased risk for subsequent mastectomy in patients treated with APBI-brachy (HR= 2.14; 95% CI 1.83−2.52, P<0.001). APBI-brachy was also associated with more acute complications, including a higher risk of hospitalization (9.6% vs. 5.7%; P<0.001) (Adjusted OR= 1.71; 1.58−1.86); and infection (8.1% vs. 4.5%; P<0.001) (Adjusted OR=1.85; 1.69−2.02; P<0.001). APBI-brachy was also associated with higher 5-year cumulative incidence of rib fracture (4.2% vs. 3.6% in WBI), fat necrosis (9.1% vs. 3.7%), and breast pain (14.9% vs. 11.7%) (P<0.001 for all comparisons), but a lower incidence of pneumonitis (0.1% vs. 0.8%, P<0.001). Discussion: APBI-brachy was associated with inferior effectiveness as well as increased acute and late toxicities compared with WBI in this cohort of older breast cancer patients. These data underscore the importance of awaiting mature results of randomized trials designed to prospectively compare these treatments before employing widespread adoption of APBI-brachy as an alternative to WBI in select patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S2-1.

Accelerated partial-breast irradiation using intensity-modulated proton radiotherapy: do uncertainties outweigh potential benefits?

“…Given the relative infancy of APBI and the evolving understanding of potential risks and benefits of APBI [23], meticulous target coverage that preserves the non-target sparing is of the utmost importance. PSPB APBI eliminates the excess dose to non-target breast tissue seen with photons while preserving the dose homogeneity in the target typical of photon-based approaches [11,13,16,24,25].…”

Impact of partial versus whole breast radiation therapy on fatigue, perceived stress, quality of life and natural killer cell activity in women with breast cancer

“…Moreover, the suitability of patient selection for breast brachytherapy (PBRT) has been called into question [52-54], with one SEER study [54] showing that 65% of women receiving PBRT fell in the unsuitable cautionary group for PBRT based on the American Society of Radiation Oncology guidelines. This may explain the increased local recurrence reported by Smith et al,[55]. At this time, definitive conclusions regarding local control and survival outcomes for PBRT must await completion of an ongoing national study comparing PBRT to WBRT [5,6].…”

Breast Cancer 2012 - New Aspects

“…Radiation with these techniques alone is still an experimental procedure since no robust data on the longterm results are available [14,15]. Even so, the techniques of partial breast radiation, especially in older patients, are in use in the USA also outside of clinical trials [16]. In a retrospective study the data from a statutory health insurance (Medicare) of patients after whole breast irradiation (WBI) were compared with those of patients after accelerated partial breast brachytherapy (APBB) [16].…”

“…Even so, the techniques of partial breast radiation, especially in older patients, are in use in the USA also outside of clinical trials [16]. In a retrospective study the data from a statutory health insurance (Medicare) of patients after whole breast irradiation (WBI) were compared with those of patients after accelerated partial breast brachytherapy (APBB) [16]. Altogether 130,535 women over 66 years of age were identified for whom costs of one of the above-mentioned therapy options were reimbursed by public health insurances between 2000 and 2007.…”

“…Only the incidence of pneumonitis was more favourable for the APBB group, 0.1 %, than that for the WBI group, 0.8 % (p < 0.001). Because of the retrospective design and the poorly balanced groups, Smith et al did not interpret their data as evidence for the inferiority of brachytherapy but rather as an urgent appeal to await the results of randomised trials before widely using such methods outside of an experimental setting [16]. This needs to be emphasised with all due clarity.…”