Margaret J Zhou1, Annemieke van Zante2, Ann A Lazar3,4, Eli R Groppo5, Adam A Garsa1, William R Ryan6, Ivan H El-Sayed6, David W Eisele7, Sue S Yom1. 1. Department of Radiation Oncology, University of California, San Francisco, California. 2. Department of Pathology, University of California, San Francisco, California. 3. Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, California. 4. Department of Epidemiology and Biostatistics, University of California, San Francisco, California. 5. Sacramento Ear, Nose and Throat, Sacramento, California. 6. Department of Otolaryngology - Head and Neck Surgery, University of California, San Francisco, San Francisco, California. 7. Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland.
Abstract
BACKGROUND: Treatment for squamous cell carcinoma (SCC) of unknown primary consists of radiotherapy (RT) +/- chemotherapy or neck dissection +/- adjuvant RT/chemoradiotherapy (CRT). We compared these strategies and identified prognostic factors. METHODS: From 1993 to 2015, 75 patients with SCC of unknown primary had RT-based or surgery-based treatment. Primary endpoints were overall survival (OS) and disease-free survival (DFS). Event-time distributions were estimated using the Kaplan-Meier method. RESULTS: Five-year OS and DFS for RT-based and surgery-based treatments were similar (OS 73% vs 68%, respectively; DFS 65% vs 64%, respectively). Among 38 patients with p16 data, 76% were p16 positive and showed improved 5-year DFS (90% vs 33%; P = .001) and OS (96% vs 33%; P < .001). Smoking history ≤10 pack-years conferred better 5-year DFS (88% vs 49%; P < .001) and OS (91% vs 59%; P < .001). CONCLUSION: RT-based and surgery-based treatments produced similar outcomes. Patients with p16-positive disease with ≤10 pack-years of smoking history and limited nodal stage constitute a "low-risk" group in SCC of unknown primary similar to that in oropharyngeal cancer.
BACKGROUND: Treatment for squamous cell carcinoma (SCC) of unknown primary consists of radiotherapy (RT) +/- chemotherapy or neck dissection +/- adjuvant RT/chemoradiotherapy (CRT). We compared these strategies and identified prognostic factors. METHODS: From 1993 to 2015, 75 patients with SCC of unknown primary had RT-based or surgery-based treatment. Primary endpoints were overall survival (OS) and disease-free survival (DFS). Event-time distributions were estimated using the Kaplan-Meier method. RESULTS: Five-year OS and DFS for RT-based and surgery-based treatments were similar (OS 73% vs 68%, respectively; DFS 65% vs 64%, respectively). Among 38 patients with p16 data, 76% were p16 positive and showed improved 5-year DFS (90% vs 33%; P = .001) and OS (96% vs 33%; P < .001). Smoking history ≤10 pack-years conferred better 5-year DFS (88% vs 49%; P < .001) and OS (91% vs 59%; P < .001). CONCLUSION: RT-based and surgery-based treatments produced similar outcomes. Patients with p16-positive disease with ≤10 pack-years of smoking history and limited nodal stage constitute a "low-risk" group in SCC of unknown primary similar to that in oropharyngeal cancer.