Clinical Topics

Positivity Rates in Oropharyngeal and Nonoropharyngeal Head and Neck Cancer in the VA

Rates of HPV positivity of the p16 biomarker in veterans were similar to those of patients with oropharyngeal head and neck tumors in the general population, but differed from general population patients with non-oropharyngeal squamous cell carcinoma.

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Head and neck cancer (HNC) continues to be a major health issue with an estimated 51,540 cases in the US in 2018, making it the eighth most common cancer among men with an estimated 4% of all new cancer diagnoses. 1 Over the past decade, human papillomavirus (HPV) has emerged as a major prognostic factor for survival in squamous cell carcinomas of the oropharynx. Patients who are HPV-positive (HPV+) have a much higher survival rate than patients who have HPV-negative (HPV-) cancers of the oropharynx. The 8th edition of the American Joint Committee on Cancer (AJCC) staging manual has 2 distinct stagings for HPV+ and HPV- oropharyngeal tumors using p16-positivity (p16+) as a surrogate marker. 2

Squamous cell carcinomas of the oropharynx that are HPV+ have about half the risk of death of HPV- tumors, are highly responsive to treatment, and are more often seen in younger and healthier patients with little to no tobacco use. 2,3 As such, there also is a movement to de-escalate HPV+ oropharyngeal cancers with multiple trials by either replacing cytotoxic chemotherapy with a targeted agent (cisplatin vs cetuximab in RTOG 1016) or reducing the radiation dose (ECOG 1308, NRG HN002, Quarterback, and OPTIMA trials). 3

The focus of many epidemiologic studies has been in the HNC general population. A recent epidemiologic analysis of the HNC general population found a p16 positivity rate of 60% in oropharyngeal squamous cell carcinomas (OPSCC) and 10% in nonoropharyngeal squamous cell carcinomas (NOPSCC). 4 There has been a lack of studies focusing on the US Department of Veterans Administration (VA) population. The VA HNC population consists mostly of older white male smokers; whereas the rise of OPSCC in the general population consists primarily of males aged < 60 years often with little or no tobacco use. 5 Furthermore, the importance of p16 positivity in NOPSCC also may be prognostic. 6 Population data on this subset in the VA are lacking as well.This study’s purpose is to analyze the p16 positivity rate in both the OPSCC and NOPSCC in the VA population. Elucidation of epidemiologic factors that are associated with these groups may bring to light important differences between the VA and general HNC populations.

Methods

A review of the Kansas City VA Medical Center database for patients with HNC was performed from 2011 to 2017. The review consisted of 183 patient records (second primaries were scored separately), and 123 were deemed eligible for the study. Epidemiologic data were collected, including site, OPSCC vs NOPSCC, age, race, education level, tobacco use, alcohol use, TNM stage, and marital status (Table).

Gender was not included because there was only 1 female patient in the cohort. Four subgroups based on site and p16 status (OPSCC p16+, OPSCC p16-, NOPSCC p16+, and NOPSCC p16-) were further analyzed. Appropriate statistical analysis (chi-square test, analysis of variance, and Kruskal-Wallis test) with IBM SPSS 24.0 (Armonk, NY) was used to find differences ( P < .05) among the means of the 4 subgroups.

Results

There were 55 (44%) patients with OPSCC and 68 patients with NOPSCC (56%). Of the 68 patients with NOPSCC, 48 (70%) were primary tumors from the larynx, 12 (18%) from the oral cavity, 4 (6%) from the hypopharynx, 2 from the nasopharynx (3%), and 2 (3%) were unknown primaries. In the OPSCC group, 41 patients were p16+ (75%) and 14 p16- (25%). In the NOPSCC group, 20 patients were p16+ (29%) and 48 were p16- (71%). There was a statistically significant difference seen in tobacco use, TNM stage, and marital status. Alcohol use trended toward significance.

The NOPSCC p16+ group had the greatest mean pack-year use (57). The lowest was in the OPSCC p16+ group (29). The OPSCC p16+ group had 37% never smokers compared with ≤ 10% for the other groups. Both the OPSCC and NOPSCC p16- groups had much more alcohol use per week than that of the p16+ groups. The differences in marital status included a lower rate of never married individuals in the p16+ group and a higher rate of marriage in the NOPSCC p16- group. The T stage distribution within the OPSCC groups was similar, but NOPSCC groups saw more T1 lesions in the NOPSCC p16- group (42% p16- vs 18% p16+). Conversely, more T4 lesions were found in the NOPSCC p16+ patients (7% p16- vs 29% p16+). More advanced nodal staging was seen in both OPSCC groups with 78% N2 or N3 in the p16+ group and 82% in the p16- group. The NOPSCC p16+ group had

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