Impact of cisplatin dose and smoking pack-years in human papillomavirus-positive oropharyngeal squamous cell carcinoma treated with chemoradiotherapy.

Abstract

BACKGROUND\nTo evaluate the impact of cisplatin cumulative dose (CDDP-D) and smoking pack-years (PYs) on cause-specific survival (CSS) and overall survival (OS) in human papillomavirus-positive (HPV+) oropharyngeal carcinoma (OPSCC) using the eighth edition tumour-node-metastasis (TNM) staging classification (TNM8).\n\n\nPATIENTS AND METHODS\nWe reviewed patients with HPV+\xa0OPSCC treated with high-dose CDDP and intensity-modulated radiotherapy between 2005 and 2015\xa0at Princess Margaret Cancer Centre. CSS and OS were compared according to CDDP-D <200/=200/>200\xa0mg/m2 stratified by TNM8.\n\n\nRESULTS\nA total of 482 consecutive patients were evaluated (stage I/II/III: N\xa0=\xa0189/174/119; CDDP-D <200/=200/>200\xa0mg/m2: N\xa0=\xa0112/220/150). Median follow-up duration was 5.1 years (range: 0.6-12.8). Five-year CSS and OS differed by stages I/II/III: 96%/85%/88% (p=0.005) and 93%/84%/78% (p\xa0=\xa00.001), respectively. Five-year CSS by CDDP-D <200/=200/>200\xa0mg/m2 was similar in stage I (98%/95%/95%, p\xa0=\xa00.74) and stage II (88%/84%/84%, p\xa0=\xa00.86)\xa0but different in stage III (76%/98%/84%, p\xa0=\xa00.02). Five-year OS by CDDP-D <200/=200/>200\xa0mg/m2 did not differ significantly among stages. In the multivariable analysis, CDDP-D <200\xa0mg/m2 did not influence CSS in the whole cohort versus\xa0=\xa0200/>200\xa0mg/m2 (p=0.53/0.79, respectively)\xa0but was associated with reduced CSS in stage III subgroup versus =200\xa0mg/m2 (=200\xa0mg/m2 versus\xa0<\xa0200\xa0mg/m2 hazard ratio [HR]\xa0=\xa00.08; 95% confidence interval [CI]: 0.01-0.67; p\xa0=\xa00.02). Higher smoking PYs had no effect on CSS (p\xa0=\xa00.34) but reduced OS in the whole cohort (HR\xa0=\xa01.14 [95% CI: 1.02-1.27], p=0.01).\n\n\nCONCLUSION\nCDDP-D correlated with neither survival nor disease-specific outcomes in this large and homogeneous HPV+\xa0cohort, although reduced CSS was observed in stageIII HPV+\xa0OPSCC receiving CDDP-D <200\xa0mg/m2. Smoking PYs were negatively associated with OS but not with CSS.