en-label, proof-of-concept study designed to evaluate the feasibility, safety, and acceptability of a prophylactic fish oil-enriched nutritional supplement (Fresubin Supportan) in patients with head and neck cancer (HNC) undergoing curative-intent chemoradiotherapy (CRT) at the University of Kansas Medical Center. The study involves daily supplementation starting two weeks prior to CRT and continuing throughout CRT, alongside weekly nutrition counseling.

This will be a single-arm, open-label, proof-of-concept (PoC) study conducted at the University of Kansas Medical Center (KUMC). The overarching goal is to assess feasibility, safety, acceptability, and preliminary efficacy signals of pre- and peri-CRT fish oil-enriched drink (Fresubin Supportan) in 15 HNC patients undergoing definitive CRT. The intervention duration will be \~8.5-9 weeks (2 weeks pre-RT + \~6.5-7 weeks during CRT). The intervention includes weekly nutrition counseling from a Registered Dietitian Nutritionist (RDN) and biospecimen collection for fatty acid analysis, FADS1/2 genotyping, and long-term banking for future biomarker discovery.