Oral Candida Colonization Among Patients With Head and Neck Cancer Undergoing Radiotherapy and Its Impact on the Severity of Oral Mucositis: A Prospective Observational Study.

Objective Oral mucositis is a common complication of radiotherapy (RT) in patients with head and neck cancer (HNC), often resulting in reduced treatment tolerance and impaired quality of life. Radiation-induced mucosal injury predisposes patients to Candida colonization, which may influence the early onset and severity of mucositis. This study aimed to determine the prevalence and temporal pattern of oral Candida colonization in patients with head and neck cancer undergoing radiotherapy and to evaluate its association with the severity of radiation-induced oral mucositis while accounting for relevant clinical factors, including age, comorbidities, and treatment-related variables. Methodology A prospective observational study was conducted on 70 patients aged 40-80 years undergoing curative radiotherapy for head and neck cancers at a tertiary care facility. Sterile swabs were collected from multiple oral sites before radiotherapy, during the third week of treatment, and at the end of radiotherapy. Samples were inoculated on Sabouraud dextrose agar to identify Candida species. Oral mucositis was assessed weekly using the World Health Organization (WHO) and Common Terminology Criteria for Adverse Events (CTCAE) scales. Statistical analysis was performed using SPSS version 25 (IBM Corp., Armonk, NY), with associations evaluated using the chi-square or Fisher's exact test. Results Among the 70 patients, 32 (45.7%) were Candida-positive by the third week of radiotherapy, progressing to 44 (62.9%) after treatment completion. Oral mucositis developed in 58 (82.9%) patients, with WHO grades 2 and 3 being the most frequent, affecting 22 (31.4%) and 16 (22.9%) patients, respectively. Candida positivity correlated with mucositis severity, observed in 14 (63.6%) patients with grade 2 and 14 (87.5%) patients with grade 3 mucositis. The oral cavity was the most common site of Candida colonization, affecting 20 (66.7%) patients. No patients were Candida-positive before radiotherapy. Conclusion Oral Candida colonization increased significantly during radiotherapy and was closely associated with the severity of oral mucositis. The early detection and management of fungal colonization may improve treatment tolerance, reduce mucosal injury, and enhance the quality of life in patients undergoing head and neck radiotherapy.