Impact of routine surveillance imaging on detecting recurrence in human papillomavirus associated oropharyngeal cancer.

Objectives: This study examines the utility of surveillance imaging in detecting locoregional failures (LRF), distant failures (DF) and second primary tumors (SPT) in patients with human papillomavirus (HPV) associated oropharyngeal cancer (OPC) after definitive chemoradiotherapy (CRT).

Methods And Materials: An institutional database identified 225 patients with biopsy proven, non- metastatic HPV+ OPC treated with definitive CRT between 2004 and 2015, whose initial post-treatment imaging was negative for disease recurrence (DR). Two groups were defined: patients with <2 scans/year Group 1 and patients with ≥2 scans/year Group 2. The Mann-Whitney test or Chi-square was used to determine differences in baseline characteristics between groups. Fine & Gray regression was used to detect an association between imaging frequency, DR and diagnosis of SPT.

Results: Median follow up was 40.8 months. 30% of patients had ≥T3 disease and 90% had ≥ N2 disease (AJCC 7th edition). Twenty one failures (9.3%) were observed, 7 LRF and 15 DF. Six LRF occurred within 24 months and 14 DF occurred within 36 months of treatment completion. Regression analysis showed Group 2 had increased risk of DR compared to Group1 (HR 10.3; p = 0.002) albeit with more advanced disease at baseline. Five SPT were found (2 lung, 2 esophagus, and 1 oropharynx) between 4.5 and 159 months post-CRT.

Conclusion: Surveillance imaging seems most useful in the first 2-3 years post treatment, and is particularly important in detecting DF. Surveillance scans for SPT has a low yield, but should be considered for those meeting lung cancer screening guidelines.