Human Papilloma Virus tumors on the head and neck are less aggressive

Researcher evaluates patients with tumors in their mouth and throats and finds that HPV cases have increased but have lower mortality.

By Karina Toledo

Agência FAPESP – A study conducted by Universidade de São Paulo’s Public Health School (FSP/USP) suggests that human papilloma virus (HPV) tumors found on the head and neck are less aggressive.

The study, which resulted in FAPESP fellow Rossana Verónica Mendoza López’s doctoral thesis, is based on data from 1,475 patients who participated in two major multicenter studies.

All of the patients had epidermoid carcinoma tumors. The location varied from the oral cavity, oropharynx (amygdala), hypopharynx (part of the throat just behind the amygdala) and larynx (the back of the throat near the esophagus).

The older study, conducted between 1998 and 2003, was coordinated by the International Agency for Research on Cancer (IARC) in five Brazilian cities, Buenos Aires and Havana and evaluated the relationship between cancers and eating, smoking, alcohol consumption and sexual practices. For Lopez’s research, only data on Goiânia, Rio de Janeiro and São Paulo were used.

The second study, titled the Genome of Cancer of the Head and Neck (Gencapo), was a FAPESP-funded Thematic Project that was conducted from 2003-2010 with the objective of identifying biomarkers for the disease.

“We conducted two types of tests to verify the prevalence of HPV infection among 1,475 patients: serology and DNA analysis. However, for the latter, we obtained tumor tissues in only 542 cases,” tells Lopez.

In the serological tests, the researchers investigated the presence of antibodies (E1, E2, E4, E6, E7, and L1) for 11 of the almost 20 types of existing HPV. Considering the results for only type 16 HPV, which is most related to the development of head and neck cancer, the prevalence of positive cases among patients in the IARC study was 55%. In the most recent study, the index leapt to 72%.

In the DNA analysis of tumor tissue, the prevalence of HPV 16 grew from 1% among the cases of the older study to 6.7% in the Gencapo study. Although the studies were not far apart, affirms the researcher, they can affirm that within a decade, there was an increase in the prevalence of HPV 16 among patients with head and neck tumors.

Less lethal

The serological tests also evaluated the presence of antibodies for oncoproteins E6 and E7, which are related to tumor invasion and virus replication. In analyzing the lifespan of patients, scientists observed that in those testing positive for HPV 16 and the E6 protein, mortality was 38% lower.

When the result was positive for HPV 16 and the two proteins (E6 and E7), mortality was reduced 66%. Considering only cases of cancer in the oropharynx, which was most associated with HPV infections and oral sex, the mortality was 83% lower.

“International studies have shown that HPV has a greater relationship with oropharynx tumors. The results of our study suggest, however, that cases of head and neck cancer with the presence of HPV infections have higher survival rates, or rather, a better prognosis. However, we still do not know why,” stresses Lopez.

According to Victor Wünsch Filho, professor at FSP/USP and leader of the study, the demographic profile and life habits of patients who were positive for oncoproteins E6 and E7 of HPV16 are possible explanations for the better prognosis.

“They form a group of young patients, with a higher proportion of women and a smaller proportion of smokers. These data deserve deeper analysis,” says Wünsch.

The study also revealed that the presence of HPV 16 proteins E6 and E7 was most frequent among patients who affirmed practicing oral sex, the main form of HPV contagion.

“The existing evidence at the moment suggests that there are more genetic mutations in the case of cancer associated with the consumption of alcohol and cigarettes, which contributes to the development of more aggressive tumors compared to those caused by HPV,” says Luisa Lina Villa, director of the Ludwig Institute of Cancer Research.

According to Lopez, although the evidence indicates that HPV is becoming a more common cause of head and neck cancer, the consumption of tobacco and alcohol accounts for the majority of cases.