DISCUSSION
The VAMHS population in our study had a lower proportion of HPV-associated oropharyngeal SCC compared with studies on nonveteran populations (29% vs 40%-80%, respectively).5,6 This disparity may indicate a true difference in these populations or may be related to a decreased prevalence of HPV infection in the population served by the VAMHS. This single-institution population did not completely correlate with previous population studies. Specifically, age at presentation (equivalent to patients with p16-negative status rather than earlier age at onset), disease stage at presentation (lower stage for patients with p16-positive status), and disease-specific survival (not improved compared with patients with p16-negative status in other studies) were dissimilar to previous investigations.2,3
The increased age and staging at presentation could be related in these patients with p16-positive status, which may further account for the lack of improved survival. Furthermore, both groups tended to use alcohol at a high proportion; whereas other populations have had a lesser degree of alcohol intake with p16 positivity.1-4 These differences may be due to variations in the habits and behavior of VA patients compared with non-VA patients.3,4
HPV-associated oropharyngeal SCC in published data has been associated with high-risk sexual behavior, lower age, and less tobacco and alcohol use.5,6 No difference was noted in tumor site predilection; however, the small size of our study could explain the lack of finding site preference shown in previous studies.2,3Other veteran-specific factors are absent in the at-large population, such as Agent Orange exposure. More than 8 million veterans (22%) from the Vietnam era self-reported Agent Orange exposure.7 Agent Orange exposure significantly predicted developing upper aerodigestive tract cancer. Oropharyngeal, nasopharyngeal, laryngeal, and thyroid cancers were significantly associated with Agent Orange exposure. Interestingly, these patients experienced an improved 10-year survival rate compared with patients not exposed to Agent Orange. This finding contrasts with our patients, who did not experience improved outcomes vs nonveteran patients with head and neck cancer.7
Suicide in veterans with head and neck cancer has been evaluated and was found at an incidence of 0.7%. Survivors of head and neck cancer are almost twice as likely to die by suicide compared with other cancer survivors. These patients have a higher rate of mental health disorders, substance misuse, and use of palliative care services.8 Sixty-five of 66 of our patients died during the 5-year observation period, although none died by suicide.
In a 2022 cohort study by Sun and colleagues, upfront surgical treatment was associated with a 23% reduced risk of stroke compared with definitive chemoradiotherapy in US veterans with oropharyngeal carcinoma.9 In our study, 58 of 66 patients (88%) received concurrent chemoradiation, possibly reflecting the more advanced stage of diagnosis in our study population. This was due to comorbidities and other health and economic factors. In our study, 43 patients (65%) died of factors not related to the disease, reflecting the overall comorbidity burden of this population. Seven patients (11%) in our 5-year study died of a documented stroke. In the study of veterans by Sun and colleagues, the 10-year cumulative incidence of stroke was 12.5% and death was 57.3%.9 Our veteran population experienced a similar incidence of strokes. These findings may need to be included when discussing the risk-benefit aspects of different treatment options with our veteran patients with oropharyngeal cancer.
To understand the influence of HPV infection on the course of oropharyngeal SCC in the VA patient population and to apply this understanding to future individualized treatment paradigms, this study can be expanded to a greater number of VA patients. p16 immunoexpression appears to be a useful surrogate for high-risk HPV infection in oropharyngeal SCC, and its ease of use supports its feasibility in further VA population analysis.10 While realizing that the veteran HPV-associated oropharyngeal SCC population differs from the civilian HPV-associated oropharyngeal SCC population, we also have realized that other unique considerations in the veteran population, such as chemical warfare exposure, mental illness, and vascular disease, complicate treatment decisions in these patients.
CONCLUSIONS
Disparities in racial distribution and tobacco use between patients with p16-positive and p16-negative status are similar to those reported in non-VA populations. In contrast, the frequently reported younger age at presentation and better disease outcomes seen in non-VA patients were not observed, perhaps due to the lower percentage of p16 expression in VA patients with oropharyngeal SCC. Whereas de-intensification of therapy may be considered for many patients with oropharygeal cancer that is HPV-associated because of improved prognosis, this approach should be undertaken with great care in this group of patients. Personalization of therapy for these HPV-associated oropharyngeal SCC in the veteran population must be adapted to mitigate this critical disparity.