2111 - Associating Weight Loss with Soft Tissue Wasting Using Daily Cone Beam CT Imaging and Autosegmentation for Head and Neck Cancer Patients Undergoing Multi-Modal Treatment Regimens

Purpose/Objective(s): Head and neck cancer patients typically receive a combination of radiation, chemotherapy, and surgery for their therapeutic regimen. Treatment-related side effects often trigger weight loss, which can lead to several complications and potentially delay treatment efforts. This study aims to characterize changes in weight and soft tissue based on daily setup imaging for patients receiving head and neck radiotherapy, enabling closer monitoring and earlier intervention for susceptible patients.

Materials/Methods: A cohort of 346 patients undergoing radiotherapy for head and neck cancer was categorized into 2 groups based on whether they also received surgery or chemotherapy. Daily cone beam CT images were acquired prior to each fraction of radiation, offering a secondary advantage of visualizing internal anatomy. An automatic segmentation tool (TotalSegmentator) was used to contour the daily scans to provide measures of soft tissue volume. Patient weights were acquired on a weekly basis. The average percent change in weight, skeletal muscle volume, and subcutaneous fat volume was tracked for each group throughout radiotherapy.

Results: At the end of radiation treatment, the average loss in total body weight across all patients was 5.5% +/- 5.0 SD. Changes in soft tissue volume were more dramatic than the established trend of weight loss, with skeletal muscle decreasing by 6.1% +/- 8.8 SD and subcutaneous fat decreasing by 10.6 +/- 16.2 SD. When comparing trends between different treatment groups, the addition of concurrent chemotherapy led to 4.0% +/- 6.4 SD (t=-8.3, p<0.001) more weight loss than the groups without chemotherapy, as well as significant skeletal muscle wasting (loss of 3.7%+/- 12.0 SD, t=-4.1, p<0.001). Surgery prior to radiation, however, did not lead to significant loss in soft tissue and weight.

Conclusion: This study demonstrates a novel method of monitoring daily soft tissue changes that align with weight loss trends experienced by head and neck cancer patients receiving radiation. Patients undergoing chemotherapy endured significantly more skeletal muscle wasting and weight loss compared to groups treated without chemotherapy. We are working to develop predictive models that incorporate relevant covariates to better understand factors associated with body compositional changes and weight loss. Overall, an improved understanding of soft tissue decomposition and risk factors for weight loss could enable earlier nutritional intervention for patients undergoing radiotherapy for head and neck cancer, supporting timely completion of treatment.