Nineteen percent of cancers among people living with HIV in North America are likely caused by smoking, aidsmap reports.

Publishing their findings in the journal AIDS, researchers studied data on 52,441 HIV-positive members of the North American AIDS Cohort Collaboration on Research and Design consortium. Between 2000 and 2015, these individuals contributed a cumulative 270,136 years of follow-up, or a median of 3.8 years. The majority of them were on antiretroviral (ARV) treatment.

During the study period, 2,306 (4 percent) of the cohort members were diagnosed with cancer, for a rate of 853 diagnoses per 100,000 people per year.

Seventy-nine percent of those diagnosed with cancer had smoked, compared with 73 percent of those not diagnosed with cancer. This difference was statistically significant, meaning it is unlikely to have occurred by chance.

After adjusting their data to account for other cancer risk factors, the researchers found that ever having smoked was associated with a 1.33-fold increase of the risk for any cancer and a 2.31-fold increase in the risk of cancer that is linked to smoking, including cancer of the lung, larynx, liver, colon, rectum, oral cavity, kidney, cervix and leukemia. The biggest disparity in risk for smoking-related cancers was for lung cancer, for which ever having smoked was associated with a 17.8-fold increased risk.

Smoking drove an estimated 19 percent of all cancers among the study population, including a respective 50 percent and 9 percent of smoking-related and non-smoking-related malignancies.

The study authors stressed the importance of HIV-positive individuals quitting smoking to reduce their risk of cancer.

To read the aidsmap article, click here.

To read the study abstract, click here.