Oropharyngeal cancers can be divided into two types, HPV-positive and HPV-negative cancers. Some types of oral HPV (known as “high risk types”) can cause cancers of the head and neck area. Other types of oral HPV (known as “low risk types”) can cause warts in the mouth or throat.
A large population-based study has confirmed the association between the presence of human papillomavirus (HPV) DNA in oropharyngeal squamous cell cancer and improved patient survival.
The team led by Marc Goodman, from Cedars-Sinai Medical Research Center in Los Angeles, California, USA, writes: “Defining those subgroups of [oropharyngeal squamous cell cancer] patients with the best survival remains a challenge, but this study adds to the growing evidence that HPV status is an important prognostic variable for patients diagnosed with this malignancy.
“Future clinical trials will need to determine optimal treatment regimens that are tailored to each patient’s HPV status and prognostic profile.”
Using data from six US population-based cancer registries, the researchers identified 529 patients diagnosed with oropharyngeal cancer between 1994 and 2005. And analysis of tumour specimens showed that 322 patients were positive for HPV16 while 56 were positive for other HPV genotypes with high oncogenic potential, such as HPV33, HPV18 and HPV35. The remaining 151 patients were negative for HPV.
HPV16-positive patients and those positive for other HPV types had a significantly higher 5-year all-cause survival rate than HPV-negative patients, at a respective 64.6% and 45.6% versus 28.1%.
And multivariate analysis established HPV status as an independent factor associated with 5-year all-cause survival. Compared with patients negative for HPV, those positive for HPV16 and for other HPV types had a significantly reduced risk of mortality at 5 years, with hazard ratios of 0.38 and 0.58, respectively.
Five-year survival was better in HPV16-positive participants than in those harbouring other HPV genotypes, but the difference only tended to significance after adjusting for confounders. The researchers speculate that some of this difference could be due to the higher percentage of other genotypes in tumours located at anatomical sites associated with poorer survival, such as the base of the tongue.
Although surgery and radiotherapy correlated significantly with reduced mortality at 5 years, “there was no evidence that treatment benefit varied by HPV status”, they report in the European Journal of Cancer.
This finding, say Goodman et al, is in contrast to previous research that has shown improved response to radiotherapy in HPV-positive compared with -negative head and neck cancer patients.
They conclude: “Biological differences between tumours, such as degree of cellular dysregulation and response to therapy, likely drive the improved prognosis among HPV-positive compared to HPV-negative patients since tobacco use, age, performance status, comorbidities, and other confounders only account for ~9% of the variation in overall survival by HPV status.”
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