ESTRO 2024 - Abstract Book

S650

Clinical - Breast

ESTRO 2024

Moderate hypofractionation with simultaneous integrated boost after conservative surgery for BCa

Roberta Tummineri 1 , Miriam Torrisi 1 , Andrei Fodor 1 , Marcella Pasetti 1 , Martina Midulla 1,2 , Laura Giannini 1,2 , Chiara Lucrezia Deantoni 1 , Barbara Longobardi 3 , Roberta Castriconi 3 , Alessia Tudda 3 , Claudio Fiorino 3 , Antonella Del Vecchio 3 , Nadia Gisella Di Muzio 1,4 1 IRCCS San Raffaele Hospital, Radiation Oncology, Milan, Italy. 2 Milano-Bicocca University, Radiation Oncology, Milan, Italy. 3 IRCCS San Raffaele Hospital, Medical Physics, Milan, Italy. 4 Vita-Salute University, Radiation Oncology, Milano, Italy

Purpose/Objective:

Moderately hypofractionated radiotherapy (HRT) to whole breast (WB) is the standard treatment for breast cancer (BCa) after conservative surgery. Simultaneous integrated boost (SIB) to the tumor bed is delivered to high risk local recurrence (LR) patients(pts). We report toxicity and outcomes in BCa pts treated with WB+SIB HRT in our Institute.

Material/Methods:

From December 2017 to March 2023 260 BCa women were treated with WB+SIB HRT after conservative surgery (right 116, left 144). Median age was 60(29-88) y. Molecular subtypes were: Luminal A 37%, Luminal B Her2- 24.5%, Luminal B Her2+ 14%, HR negative Her2+ 4.5%, Triple negative (TN) 18%. The remaining 2% were in situ BCa. Chemotherapy (CHT) was prescribed to 132 pts (50.7%): neoadjuvant 14.2%, adjuvant 38%, concomitant 0.3%. Adjuvant endocrine therapy was prescribed for 186 pts (71.5%)(Aromatase Inhibitors or Tamoxifen-/+LH-RH analogue), 48pts (18.5%) underwent HER2-targeted therapy. HRT was delivered with Tomotherapy (79.2%), VMAT (20%) or 3DCRT (0.8%), to a total dose of 40.05Gy to WB and 48Gy to the tumor bed, in 15fractions. Acute and late toxicity and cosmesis were registered according to RTOG, SOMA-LENT and Harvard breast cosmesis scale respectively.

Table 1: Acute and late toxicity according to RTOG and SOMA-LENT scale respectively.

ACUTE TOXICITY

G0

G1

G2

G3

Breast erythema and/or edema

27 (10%)

194 (75%)

36 (14%)

3

(1%)

LATE TOXICITY

G0

G1

G2

G3

Hyperpigmentation

160 (64%)

89 (35.2%)

2

0

(0.8%)

Edema

204 (81%)

36 (14.5%)

10

1 (0.5%)

(4%)