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Poster Display session 2

3736 - Safety of hypofractionated whole breast irradiation after conservative surgery for patients aged less than 60 years: a multi-center comparative study.

Date

29 Sep 2019

Session

Poster Display session 2

Presenters

Icro Meattini

Citation

Annals of Oncology (2019) 30 (suppl_5): v55-v98. 10.1093/annonc/mdz240

Authors

I. Meattini1, L. Livi1, K. Kim2, J. Kim2, W. Jung2, E. Olmetto1, I. Desideri1, C. Saieva3, C. Becherini1, V. Salvestrini1, A. Fourquet4, Y. Kirova4, P. Poortmans4

Author affiliations

  • 1 Department Of Biomedical, Experimental, And Clinical Sciences, University of Florence, 50134 - Firenze/IT
  • 2 Radiation Oncology, Ewha Womans University College of Medicine, 07985 - Seoul/KR
  • 3 Cancer Risk Factors And Lifestyle Epidemiology Unit, Institute for cancer research, prevention and clinical network (ISPRO), Firenze/IT
  • 4 Radiation Oncology, Institut Curie, 75005 - Paris/FR
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Resources

Abstract 3736

Background

For decades, conventionally fractionated whole breast irradiation (CF-WBI) was used after breast conserving surgery (BCS). Pivotal phase 3 trials on hypofractionated-WBI (HF-WBI) showed its non-inferiority as compared to CF-WBI. However, younger patients (<60 years) are not currently worldwide treated with HF-WBI. The aim of this multi-center comparative study is to confirm the safety of HF-WBI in a real-life series of younger patients.

Methods

Between 2010 and 2016, a total of 786 patients aged less than 60 years old with early stage breast cancer were treated with postoperative WBI after BCS in three breast cancer centers: 340 underwent HF-WBI while 446 were treated with CF-WBI. Acute toxicity was evaluated at the end of WBI. Late toxicity was evaluated at 6, 12, 24, and 36 months.

Results

At univariate logistic analysis, hypofractionation showed a significant protective effect in terms of acute edema (p = 0.0001), acute wet desquamation (p = 0.009), chronic edema (p = 0.0001), chronic erythema/pigmentation (p = 0.0001), and breast fibrosis (p = 0.0002). At multivariate logistic analysis, hypofractionation was independent significant factor for acute edema (OR 0.09, 95% CI 0.02 to 0.48; p = 0.005), acute wet desquamation (OR 0.07, 95% CI 0.009 to 0.59; p = 0.014), and chronic edema (OR 0.18, 95% CI 0.04 to 0.75; p = 0.018). Significant association between individual characteristics and toxicity (grade 2 or more) are summarized in Table.Table:

215P

ToxicityNProtective factorp-valueOR (95%CI)Risk factorp-valueOR (95%CI)
Acute edema43Hypofractionation Dmax/Prescribed dose° <107%0.0001 0.0010.09 (0.03-0.30) 0.16 (0.06-0.46)Chemotherapy0.0022.63 (1.42-4.90)
Chronic edema50Hypofractionation Dmax/Prescribed dose° <107%0.0001 0.0030.20 (0.09-0.44) 0.31 (0.14-0.66)EIC presence Boost dose >10 Gy Breast size >492 cc0.0001 0.032 0.0033.0 (1.66-5.46) 9.02 (1.21-67.45) 2.67 (1.41-5.05)
Acute erythema/ pigmentation163HER2 positive status Trastuzumab0.002 0.0220.30 (0.14-0.63) 0.39 (0.18-0.87)Smoking habits Boost dose >10 Gy Breast size >492 cc0.001 0.038 0.0022.14 (1.37-3.32) 2.60 (1.06-6.41) 1.78 (1.24-2.54)
Chronic erythema/ pigmentation110Hypofractionation Dmax/Prescribed dose° <107%0.0001 0.0010.40 (0.25-0.63) 0.45 (0.28-0.73)EIC presence Positive FSM Boost dose >10 Gy Breast size >492 cc0.0001 0.002 0.007 0.0342.39 (1.54-3.71) 3.47 (1.56-7.71) 15.43 (2.08-114.3) 1.58 (1.04-2.41)
Acute wet desquamation20Hypofractionation Dmax/Prescribed dose° <107%0.009 0.0470.14 (0.03-0.61) 0.29 (0.08-0.99)---
Breast fibrosis117Hypofractionation Tumor grade Ki67 index Dmax/Prescribed dose° <107%0.0002 0.022 0.023 0.0170.44 (0.29-0.68) 0.53 (0.31-0.92) 0.60 (0.38-0.93) 0.58 (0.37-0.91)EIC presence Boost dose >10 Gy Breast size >492 cc0.0001 0.022 0.00013.03 (1.99-4.62) 6.76 (2.04-22.45) 2.84 (1.83-4.41)

Conclusions

HF-WBI showed significantly improved toxicity outcomes in terms of both acute skin edema and wet desquamation, and chronic skin edema. HF-WBI after BCS should replace CF-WBI independently of age.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

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