121MO - Acute toxicity associated with a 3-week versus a standard 5-week regimen for locoregional breast radiotherapy delivered in the UNICANCER HypoG-01 phase III trial

Background

In most countries, the 5-week normofractionated (NF) locoregional radiotherapy (RT) is still the standard of care for breast cancer with an indication for regional lymph node irradiation. HypoG-01 (NCT03127995) is a randomized phase 3 clinical trial evaluating the safety and efficacy of a 3-week moderate hypofractionated (HF)-RT against NF-RT regimen. Here, we report for the first time the acute toxicity results, a secondary endpoint of the trial.

Methods

Women with pT1-3 pN0-3 M0 breast cancer were randomized 1:1 after surgery to receive either HF-RT: 40 Gy/15 fractions/3 weeks or NF-RT: 50 Gy/25 fractions/5 weeks. Acute toxicities were graded using CTCAE V4.0 at baseline, weekly during RT, and 1 month after the end of RT (end of treatment visit); the maximum grading is reported. Since arm lymphedema is the primary endpoint of the trial, it is not included in the acute toxicities of interest.

Results

From 09/2016 to 03/2020, 29 French sites enrolled 1265 women (HF-RT arm: 633, NF-RT arm: 632). All patients (median age: 58 years) received their allocated RT and completed their scheduled end of treatment visit. Acute grade 3 toxicities were rare in both treatment arms (HF-RT: 5.4%, NF-RT: 5.7%) and no grade 4-5 toxicities were observed (Table). The rate of overall grade 2 or higher acute toxicities was lower with HF-RT (38.4%) than with NF-RT (48.1%). Grade 2 or higher dermatitis were more frequent in patients with BMI ≥30 in both arms: 34/118 (29%) in HF-RT and 59/124 (48%) in NF-RT. In total 18 patients experienced at least 1 acute Serious Adverse Event (HF-RT: 10, NF-RT: 8) of which only 2 were considered treatment-related (HF-RT: 1, NF-RT: 1). Table: 121MO

Acute adverse events of interest

Conclusions

In women receiving locoregional RT, acute toxicities with a 3-week moderately hypofractionated regimen were mild and raised no important acute safety concerns. Further long-term follow-up is ongoing.

Clinical trial identification

NCT03127995, Release date: 23/06/2016

Editorial acknowledgement

We thank Lilian AMREIN (R&D UNICANCER) for medical writing assistance of the abstract.

Legal entity responsible for the study

UNICANCER.

Funding

The French National Cancer Institute (PHRC-K).

Disclosure

S. Rivera: Financial Interests, Personal, Invited Speaker: Pfizer; Financial Interests, Personal, Invited Speaker: Eisai; Financial Interests, Personal, Invited Speaker: Lilly; Non-Financial Interests, Institutional, Leadership Role: The UNICANCER group of Translational research and development in RADiation oncology (UNITRAD). J. Clavier: Financial Interests, Personal, Stocks/Shares: Onco Outcome. S. Michiels: Financial Interests, Personal, Advisory Role: IDDI; Financial Interests, Personal, Advisory Role: Janssen Cilag; Financial Interests, Personal, Advisory Role: Amaris; Financial Interests, Personal, Advisory Role: Roche; Financial Interests, Personal, Advisory Board: Hexal; Financial Interests, Personal, Advisory Board: IQVIA; Financial Interests, Personal, Advisory Board: Roche; Financial Interests, Personal, Advisory Board: Sensorion; Financial Interests, Personal, Advisory Board: Biophytis; Financial Interests, Personal, Advisory Board: Servier; Financial Interests, Personal, Advisory Board: Yuhan. All other authors have declared no conflicts of interest.