Discussion
This is the first population-based study that confirms worse
HPV-associated OPSCC survival outcomes in black patients across a range
of adjustment sets incorporating demographic, clinical, and
individual-level SES variables. It has previously been documented that
racial differences in SES and access to care are significant
determinants of head and neck cancer disparities.(11,12,16) In OPSCC,
racial differences in HPV tumor-status have been shown to contribute to
the survival disparity.(17) However, the relative contribution of
tobacco use, alcohol use, treatment, and SES to racial disparities in
HPV-associated OPSCC has not been determined. Our analysis with
sequential adjustment sets demonstrates that racial differences in SES
contributes to some but not all of the disparity.
Our findings build upon the growing evidence in current literature for
the presence of racial disparities in OPSCC. In a large database
analysis of OPSCC stratified by HPV-status, Faraji et al. found that
there was a weak but non-significant trend towards worse overall
survival (OS) among black patients with HPV-associated OPSCC after
adjusting for age, sex, race, year of diagnosis, insurance status,
income, education, rural residence, facility region, TNM stage,
Charlson‐Deyo score, and treatment.(18) In an analysis of the SEER
database among patients with HPV-associated OPSCC, black patients had
significantly worse cancer-specific mortality than white patients even
after adjusting for county-level indicators of SES.(19) In another
study, no racial difference in OS was found when controlling for
treatment received in the Veteran’s Affairs medical system.(20) It is
possible that the more homogenous care afforded by the VA system could
have mitigated some of the racial disparity attributable to differences
in SES and access to care.
There may be several explanations for the persistence of the racial
disparity in OS after adjustment for clinical and socioeconomic factors.
First, unmeasured confounders in socioeconomic factors, physician and
system factors, and access to care may exist. We found that black
patients were more likely to have a low income compared to white
patients, but our sample lacked the power to adjust for other variables
such as frequency of primary care visits or routine dental visits.
Studies have found that patients lacking routine dental visits are
diagnosed at more advanced stages of head and neck cancer,(21–23)
although it is unknown if this pattern varies by race. In the past,
racial disparities were largely attributed to genetic differences, but
it is now recognized that race is a complex social construct and genetic
factors are not likely to integrate with socially-defined racial groups
as previously thought.(24)
Our study has several limitations. First, our study population had a
small number of black patients with HPV-associated OPSCC. It should be
noted that this is a limitation nationally, thereby limiting precise
estimation of differences in this study population. Also, p16 testing
was not routinely performed at the time of data collection for this
study so our sample likely underestimates the true number of
HPV-associated OPSCC patients in [Blinded for peer review]. Given
the small sample size of our study, it is important to recognize that
some of the non-significant findings may be due to lack of statistical
power rather than a true non-effect. Efforts are being undertaken to
combine databases to increase the sample size of black patients with
HPV-associated OPSCC for future validation studies. Another limitation
is that the [Blinded for peer review] database did not collect data
on patient comorbidities, which may confound the relationship between
race and OS. Disease specific mortality was not included in the analysis
due to a lack of data on the specific cause of death for many of the
[Blinded for peer review] patients.
Our findings may have implications for cancer treatment and future
research directions. There is strong evidence to support that patients
with HPV-associated OPSCC have improved treatment response and survival
outcomes compared to patients with HPV-negative disease.(25) These
findings have led to efforts to de-intensify treatment with the goal of
alleviating therapy-related morbidity and mortality. Our results suggest
that black patients with HPV-associated OPSCC may have worse outcomes
despite their HPV-positive tumor status, and therefore, may not receive
the same benefits from treatment deintensification. It is important to
note that in our sample, we found no differences by race with regards to
treatment type or number of treatments modalities received. Future
de-intensification trials should closely monitor survival outcomes by
race to ensure that this disparity is not being propagated.