Oropharyngeal candidiasis caused by non-albicans yeast in patients receiving external beam radiotherapy for head-and-neck cancer

Purpose: To characterize non-albicans Candida oral infections in patients with head-and-neck cancer receiving external beam radiotherapy (EBRT) with or without concurrent chemotherapy. Methods and Materials: Thirty-seven patients with head-and-neck cancer received EBRT in 2.0-Gy daily fractions to a median dose of 60.4 Gy (range 38-82.8, mean 64.6). They were followed for oropharyngeal candidiasis (OPC) confirmed by positive examination, positive KOH smear, and/or positive swab or swish culture. Samples were identified and plated on chromogenic media to identify non-albicans yeasts. Colonies were plated on Sabouraud dextrose slants for microdilution antifungal susceptibility testing to fluconazole. DNA typing, including karyotyping, restriction fragment length polymorphism analysis, and Southern blot hybridization with the moderately repetitive Ca3 probe, was performed on selected isolates to confirm individual species. Results: Of the 37 patients, 10 (27%) developed OPC, and 26 (70.3%) displayed Candida carriage state. The median EBRT dose at time of positive culture was 22.5 Gy and at time of OPC was 28.6 Gy. Of the 6 patients receiving chemotherapy and EBRT, 4 (66%) developed OPC at median dose of 27.6 Gy. Three (8%) of 37 patients were infected with non-albicans Candida, and 3 (30%) of all 10 infections were caused by these organisms. Conclusion: Non-albicans Candida is emerging as a relatively common cause of OPC in head-and-neck cancer patients. Chromogenic media are helpful to screen these infections. Our data also suggest a greater likelihood of developing OPC in patients receiving concomitant chemotherapy and EBRT.