Salivary CD44 and Total Protein Levels to Detect Risk for Oral and Oropharyngeal Cancer Recurrence

Importance Oral and oropharyngeal cancer have low survival rates, and incidence continues to increase. Objective To determine whether soluble CD44 and total protein (TP) are useful for monitoring head and neck cancer recurrence, either used in a point-of-care (POC) test or as individual laboratory-based biomarkers. Design, Setting, and Participants This multi-institutional nonrandomized clinical trial testing a novel diagnostic/screening assay took place across the University of California, San Diego; Johns Hopkins University; the Greater Baltimore Medical Center; New York University; and the San Diego Veterans Affairs Hospital. Patients with newly biopsy-proven, untreated oral cavity and oropharyngeal cancer were enrolled. Patients were enrolled April 2017 to April 2019, and data were analyzed December 2022 to June 2023. Exposure POC salivary oral rinse test. Main Outcomes and Measures Oral rinses were collected at pretreatment baseline and 3, 6, 12, and 18 months after completion of therapy; participants were then followed up for 3 years to define disease status. Associations of baseline characteristics with a positive test were evaluated by Fisher exact test. The association of a positive value on the CD44 or TP test with progression-free survival was evaluated in an adjusted multivariable proportional hazards model. Results Of 172 patients enrolled, the mean (SD) age was 62.5 (10.2) years, and 122 (70.9%) identified as male. Additionally, 92 patients (53.3%) had never smoked, 99 (57.6%) formerly or currently drank alcohol, and 113 (65.7%) presented with oropharyngeal cancers, which were positive for human papillomavirus in 95 (84.1%). Tumor site was associated with test results at baseline; patients with oral cavity cancer had a higher baseline positive POC test rate (47 of 51 [92.2%]) compared to patients with oropharyngeal cancer (85 of 110 [77.3%]). Using Cox regression models with CD44 or TP level as a time-varying covariate, a higher CD44 level showed a statistically significant association with a higher hazard of recurrence (hazard ratio, 1.06; 95% CI, 1.00-1.12), though the TP level was not statistically significant. In multivariate adjusted analysis, higher CD44 and TP levels were associated with increased hazard ratios of recurrence of 1.13 (95% CI, 1.04-1.22) and 3.51 (95% CI, 1.24-9.98), respectively. Conclusion and Relevance In this multi-institutional nonrandomized clinical trial of an assay, posttreatment longitudinal monitoring for elevated salivary CD44 and TP levels using an enzyme-linked immunosorbent assay–based laboratory test identified patients at increased risk of future cancer recurrence. The CD44 and TP rapid POC test holds some promise, but further development is needed for this indication. Trial Registration ClinicalTrials.gov Identifier: NCT03148665