Study shows a decrease in cervical cancer but a rise in other human papillomavirus–related cancers

Abstract

S creening for and vaccinating against human papillomavirus (HPV) appears to be paying off, at least in terms of reducing the incidence of invasive cervical cancer. A recent study published in the Journal of Clinical Oncology that examined the incidence and trends of HPV-related cancers in the United States over the last 15 years found a significant decrease in invasive cervical cancers in women.1 Using data gathered between 2001 and 2017 from the US Cancer Statistics program, investigators looked at the incidence of HPV-related cancers since Food and Drug Administration approval of the HPV vaccine in 2006. They found a total of 393,298 cases of HPV-related cancers in women and 264,019 HPV-related cancers in men. In women, the study found that the incidence of all HPVrelated cancers was 13.68 per 100,000 women. Of these cancers, 52% were cervical cancer. Over 16 years, the study found that the incidence of cervical cancer decreased at an annual percentage change (APC) of approximately 1% (APC, 0.13%). For younger women aged 20 to 24 years, there was an even higher APC of approximately 4.63%. This higher decreased cervical cancer incidence in younger women suggests an association with the HPV vaccine according to the senior author of the study, John C.-K. Chan, MD, who is the director of gynecologic oncology at the California Pacific Medical Center in San Francisco. “Even before vaccination, you see a decrease in cervical cancer of about 1% to 2% with screening,” he says, “but after the vaccine there is an associated decrease of over 10% in the younger patients who were eligible for vaccination.” For other HPV-related cancers, however, incidence rates are on the rise. Women had a significant rise in oropharyngeal cancers (APC, 0.77%), anal and rectal cancers (APC, 2.75%), and vulvar cancers (APC, 1.27%; P < .001 for all 3 cancers). Using a projection model to estimate future trends, investigators have predicted that the incidence of anal/rectal cancers will surpass cervical cancers in women older than 50 years by 2025. For men, the incidence of all HPV-related cancers was also on the rise and accounted for 11.0 per 100,000 in 2017, of which 81% were associated with oropharyngeal cancer. Over 16 years, the study found that all HPV-related cancers in men significantly increased at a rate of 2.36% (P < .001) per year. The highest increased annual incidence was in oropharyngeal cancer (APC, 2.71%), which was particularly high in men aged 65 to 69 years (APC, 4.24%; P < .001 for both). The rise in oropharyngeal cancer in men is particularly striking and represents a 5-fold increase in comparison with the same rise in women, says Dr. Chan. “We were surprised by the significant increases in oropharyngeal cancers,” he says, adding that the 5-fold increase in men in comparison with women points to HPV as an important cause of this cancer because of data showing that only approximately 30% of these cancers are attributable to social behavioral determinants of health such as drinking and smoking. “Previous studies have shown that men may have a more difficult time clearing the HPV virus from their oropharyngeal area compared to women,” he says. Dr. Chan emphasizes that these results represent incidence data and not vaccination data. “This is the challenge of our study: We do not have vaccination data as do countries such as Sweden with National Healthcare Systems that document all vaccinated people,” he says. Without exact numbers of vaccinated people, some speculation is involved in predicting future trends. Dr. Chan suspects that the incidence of oropharyngeal cancers, which often appear in older men, many of whom have not been vaccinated, will start to diminish as younger men receive the HPV vaccine. “We need to encourage continued increased uptake of the HPV vaccine,” says Dr. Chan. “We are seeing early encouraging results that invasive cervical cancer is decreasing at the population level, and we hope for more encouraging results in these other HPV-related cancers as vaccinated populations get older.” What is concerning, says Dr. Chan, are the increases in HPV-related cancers that are not part of current screening. “We need to potentially investigate screening individuals, for example, in the dentist office for oropharyngeal cancers, or during the PAP test for anal-rectal cancers,” he says.