Cancer prevention more important than ever in HIV population

Thanks to highly effective antiretroviral therapy patients with HIV infection are living longer than ever - long enough to develop cancer, a new study shows.

Targeted cancer screening and prevention strategies are needed in the HIV population, the study team concludes in a report online October 5 in Annals of Internal Medicine.

While cancer is "increasingly common" among people with HIV, it's been unclear whether this was due to them living longer or a true increase in the incidence of cancer, Dr. Michael Silverberg of Kaiser Permanente Division of Research in Oakland, California, and colleagues point out.

To investigate, they compared trends in cumulative cancer incidence by age 75 in more than 86,000 HIV-infected adults and nearly 197,000 uninfected adults.

"The setting for the study, NA-ACCORD, is a unique resource as it is among the largest HIV studies with high-quality cancer data, and which combines the collective experience of more than 20 longitudinal HIV studies in the U.S. and Canada," Dr. Silverberg told Reuters Health.

The study found that patients with HIV infection have about a one in 25 chance each of developing Kaposi sarcoma (KS), non-Hodgkin lymphoma (NHL) or lung cancer by age 75. "These were the most common cancers seen in our population," Dr. Silverberg said by email.

Patients with HIV infection also had an increasing cumulative incidence over time of developing anal, colorectal and liver cancer.

"This is easily interpretable information that can be used by HIV patients and their providers. It can also be used to help inform public health initiatives to reduce cancer risk, such as prioritizing smoking cessation and lung cancer screening," Dr. Silverberg commented.

"We were able to tease out reasons for the changes in cancer risk over time," he explained. "As we expected, a consequence of living longer is that these patients are now experiencing cancer. For some cancers, such as anal, colorectal and liver cancer, this is the only reason that the risk was observed to increase over time. For other cancers, such as lung cancer, Hodgkin's lymphoma and melanoma, the picture is more complex with no observed change over time. This is because HIV patients are aging and experiencing a general decline in risk factors, such as smoking. Our study was uniquely suited to look at these different reasons for the changing risk of cancer over time," Dr. Silverberg told Reuters Health.

Specifically, by age 75, the cumulative incidence of KS in patients with and without HIV was 4.4% and 0.01%, respectively; for NHL, 4.5% and 0.7%; lung cancer, 3.4% and 2.8%; anal cancer, 1.5% and 0.05%; colorectal cancer, 1.0% and 1.5%; and liver cancer, 1.1% and 0.4%. The rates were less than 1% for Hodgkin lymphoma, melanoma and oral cavity/pharyngeal cancer in patients with or without HIV.

The researchers say targeted cancer screening and prevention efforts are needed in the HIV population.

"Annual lung cancer screening with low-dose computed tomography is recommended for heavy smokers aged 55 to 80 years in the general population. The high smoking prevalence in persons with HIV, along with lung cancer incidence similar to that of AIDS-defining cancer, suggests that smokers with HIV should be compelling candidates for screening," they write.

"However, research is urgently needed to inform lung cancer screening policy for persons with HIV by clarifying the benefits versus harms of screening, because there is potential for harms resulting from a high false-positive rate due to elevated incidence of lung infections and other pulmonary diseases," they caution.

The increase in colorectal cancer risk among persons with HIV points to a need for increased screening among people with HIV aged 50 to 75 years, as recommended for the general population, they add.

The increase in anal cancer risk "highlights the need for further evidence about the harms and benefits of anal dysplasia screening." And it would be "prudent for physicians to be alert for early signs and symptoms of KS and NHL," the team notes.

As for primary prevention, "development of targeted smoking cessation interventions for persons with HIV is an obvious priority," the researchers write.

Consideration should also be given to the human papillomavirus (HPV) vaccine for prevention of anal cancer, they say.

"Although there is concern that high prevalence of HPV infection among persons with HIV may render vaccination ineffective, the vaccine has, in fact, been found to be immunogenic in persons with HIV. This suggests that vaccination has the potential to substantially decrease the burden of anal and possibly HPV-related OP cancer, although further research is clearly needed."

Finally, the researchers say the increasing risk for liver cancer over time points to a need to ensure universal hepatitis B virus (HBV) vaccination for HIV-infected adults who are HBV-seronegative, as already recommended, and to provide appropriate HBV (and HCV) treatment.

The study had no commercial funding.

SOURCE: http://bit.ly/1McydBf

Ann Intern Med 2015.