Impact of systemic comorbidities and diabetes mellitus on survival in head and neck cancer: a cohort study

Background. The prognosis for patients with locally advanced head and neck cancer is often complica­ted by systemic comorbidities. The specific impact of metabolic disorders, particularly diabetes mellitus, on treatment outcomes remains a critical interdisciplinary issue. Particularly, metabolic disorders such as diabetes mellitus are increasingly recognized as significant modifiers of cancer progression and treatment tolerance. Hyperglycemia can impair immune function and promote tumor growth, while also increasing the risk of postoperative complications. Therefore, understanding the interplay between endocrinological comorbidities and oncological outcomes is crucial for developing integrated patient management strategies. Aim of the study was to analyze the impact of the comorbidity burden, quantified by the Charlson Comorbidity Index (CCI), on treatment tolerance, complication rates, and overall survival in patients with stage III–IVa locally advanced hypopharyngeal cancer. Materials and me­thods. A retrospective analysis of medical data from 123 patients treated between 2013 and 2024 was performed. They were stratified into risk groups based on the CCI. Primary endpoints were overall survival and the incidence of pharyngocutaneous fistula. For the primary analysis, the cohort was stratified into three clinically relevant risk groups based on the calculated CCI scores: low-risk (CCI 0–1; n = 54), moderate-risk (CCI 2–3; n = 41), and high-risk (CCI ≥ 4; n = 28). Results. A higher CCI score strongly correlated with worse outcomes (p < 0.001). Notably, the pre­sence of pre-existing diabetes mellitus was associated with a higher incidence of severe postoperative complications. In multivariate analysis, a high CCI score (≥ 4) was the strongest independent predictor of mortality (hazard ratio 3.15; p < 0.001), surpassing TNM stage. Conclusions. The overall comorbidity burden is a key prognostic factor in locally advanced head and neck cancer. These findings underscore the importance of meticulous metabolic control and a multidisciplinary approach involving endocrinologists in the management of head and neck cancer patients to improve surgical outcomes and overall survival.