ESTRO 2021 Abstract Book

S679

ESTRO 2021

PD-0844 Sarcopenia evolution in stage III lung cancer treated with photon or proton chemo-radiotherapy A. Angrisani 1,2 , D. Hattu 2 , L. Hendriks 3 , S. Peeters 2 , B. Reymen 2 , J. Van Loon 2 , K. Verhoeven 2 , L. In ‘t Ven 2 , J. Dhont 2 , D. De Ruysscher 2 1 University "L. Vanvitelli", Precision medicine - Radiation Oncology , Naples, Italy; 2 Maastro clinic, GROW School for Oncology, Maastricht University Medical Centre+, Department of Radiation Oncology, Maastricht, The Netherlands; 3 Maastricht University Medical Centre, GROW School for Oncology and Developmental Biology, Department of Respiratory Medicine, Maastricht, The Netherlands Purpose or Objective Sarcopenia at diagnosis or early during chemo-radiotherapy (CRT) is related to poor outcomes in lung cancer patients (Sanders 2016, Burtin 2020). Strategies to decrease sarcopenia are therefore needed. We hypothesized that stage III lung cancer patients treated with proton therapy (PT) would have less early-onset (i.e. during radiotherapy) sarcopenia compared to photon treatment (IMRT/VMAT). Materials and Methods Forty-two photon and Thirty-four proton patients with stage III lung cancer, treated with chemo-radiotherapy (platinum doublet and a total dose of 60 Gy) with curative intent between 2019 and 2020 were included. The two groups did not have baseline differences (WHO performance status 0-1, Age, co-morbidities). The pectoral muscle volume, previously shown to be a reliable measure of sarcopenia, was evaluated with planning CTs, daily CBCT, or re-planning CT scans. The pectoral muscles were delineated for each patient on both images, at the beginning and at the end of radiotherapy. We compared the differences in the pectoral muscle volume changes (ΔPM) between the beginning and the end of radiotherapy (median time, 32 days) between IMRT/VMAT and PT treated patients. Results Out of 76 patients with a median age of 69 years, 5 were excluded because of inadequate image quality. Overall, a decrease in the pectoral muscle volume was observed in both groups (Overall ΔPM= -0,9 cm3). The mean ΔPM values were Δ= -1,1 and Δ= -0,7, in IMRT/VMAT and PT patients, respectively (p= 0,11). However, a higher proportion of PT-treated patients (9/34, 26.5 %) had an increase in PM>1cc compared to IMRT/VMAT (6/42, 14.2 %) (p=0.05). The ΔPM did not correlate with the GTV, the mean dose to the PM, tumor histology, and the gender.

Conclusion These early results may suggest that PT could have a beneficial effect on preventing the development of sarcopenia in stage III lung cancer patients treated with chemo-radiotherapy. Further and wider studies are needed to substantiate these findings.

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