ESTRO 2020 Abstract book

S164 ESTRO 2020

Purpose or Objective To evaluate early and late reactions, local control and survival of elderly breast cancer (BC) patients (pts) treated with adjuvant once-weekly hypofractionated radiotherapy (RT), either with Intensity-modulated radiotherapy (IMRT) or 3D conformal radiotherapy (3DCRT). Material and Methods From 7/2011 to 7/2018, 271 BC pts were given received 5.7 Gy once a week for 5 weeks to the whole breast, without boost to the tumor bed, after breast conserving surgery. Data were extracted from a dedicated databank for research projects called “Adjuvant radiation treatments with intensity-modulated radiotherapy and/or hypofractionated schedules for breast cancer” which was notified to the IEO Ethical Committee. Pts were eligible if affected by T1-T3 invasive BC, with no or limited axillary involvement. The scheme was offered to elderly women (age threshold of 65 years) and to those with commuting difficulties or disabling diseases. Results Median age was 76 (45.5-86.4) years. Median follow-up was 2.92 (0.10-7.01) years. Most of BC were T1 (77%), while the remaining were T2 (22%), T3 (0.4%). Axillary status was negative in 68.3%, minimally involved in 14.4% (pN1) and not assessed in 17.3% of the cases (Nx). Most of the women received adjuvant hormonal therapy (84.1%), while 10.7% received chemotherapy +/- hormonal therapy. The schedule was delivered either with 3DCRT (n=133) or with IMRT (n=138). No statistically significant difference was observed between the two techniques in terms of toxicity and efficacy. Maximum acute toxicity at the end of RT for 271 pts was as follows: grade (G) 1, 2 and 3 erythema in 63.5%, 7% and 0.4% of pts, respectively. G2 edema was detected in 10% of pts. Desquamation occurred in 4.4% as G1 and 1.5% as G2 of cases. At median 18.1 (6.0-55.2) months follow up, LENT-SOMA assessment was available for 141 pts. Fibrosis (G1, G2 and G3 in 47.5%, 10.6% and 1.4%, respectively) and skin changes (G1 and G2 hyper- or hypo-pigmentation in 29.8% and 2.1%, respectively, G1 and G2 telangiectasia in 3.5% of pts) were observed. A minority complained pain of G1 (19.1%) and G2 (1.4%) intensity. At 2.92 years, overall survival was 97.8% (94.5-99.1) ( Table 1 ) and disease-free survival was 96.3% (92.2-98.3) ( Table 2 ). There was a total of 5 (1.9%) isolated locoregional recurrences: 4 involved the breast and 1 the axillary lymph nodes. Predictive factors for toxicity were breast volume >500 cm 3 for acute toxicity, while none was correlated with late toxicity.

Conclusion Toxicity was mild and acceptable with high pts’ satisfaction. Local control was acceptable and overall survival was 97.8% at 3 years. In this series, the use of 3DCRT or IMRT for the treatment of elderly BC pts treated with adjuvant once-weekly hypofractionated RT did not differ in terms of toxicity and efficacy. Such a scheme was well accepted by pts, especially by those with difficulties in commuting and with disabling associated disease.