ESTRO 2024 - Abstract Book

S589

Clinical - Breast

ESTRO 2024

Results:

Median age is 60 years. There were 64 (62.75%) right breasts, and 38 (37.25%) left breasts. Treatments were delivered in five 5.2Gy daily fractions in 78.43% (n=80), or in fifteen 2.67Gy daily fractions in 21.57% (n=22). Eleven women (10.78%) were treated with ABC, all of them with left breast disease. Five patients (4.90%) had radiotherapy after mastectomy. The rest had breast-conserving surgery. An integrated boost was administered in 98 (96.08%) treatments, with a median boost dose of 29.5Gy (29.5-31.6) in the patients who received 5 fractions, and a median boost dose of 48Gy (48-49.5) in the patients that received 15 fractions. Patients were classified into three categories: treatment in 15 fractions, with nodal region coverage (group I. n=18), 15 fractions, without nodal region coverage (group 2. n=4), and 5 fractions, all without nodal region coverage (group III. n=80). Median breast PTV (bPTV= contoured breast PTV – boost PTV) was 1110.97cc, 656.93cc, and 1031.68cc for groups I, II, and III, respectively. Median boost PTV volume, 37.39cc, 17.64cc, and 21.97cc. Median V105% for bPTV was 5.04% in group I, 3.75% in group II, and 2.24% in group III. Median V110% for bPTV was 1.72% in group I, 2.35% in group II, and 0.75% in group III. Conformity index for bPTV was 0.82, 0.79, and 0.82 for each group respectively. Conformity index for boost PTV was 0.75, 0.75, and 0.58 for groups I, II, and III. V20Gy for ipsilateral lung was 20.43%, and 14.06% for groups I, and II, and V12Gy for ipsilateral lung was 15.27% for group III. Median heart dose was 3.09Gy, 3.22Gy, and 2.64Gy, for groups I, II, and III. In patients with left breast treatments, D5% for the heart was 9.71Gy, 8.49Gy, and 6.91Gy, respectively for each group. Standard deviations are detailed in table1.