Cervical screening, high-grade squamous lesions, and cervical cancer in illicit drug users

Women who use illicit drugs ("drug users") are exposed to human papillomaviruses (HPVs) from lifestyle risks that include sex risk behaviors, human immunodeficiency virus infection, and high levels of tobacco smoking. Both HPVs and tobacco smoking are recognized causes of cervical cancer, but little is known about risk in drug users. We sought to examine risk of cervical neoplasia and to estimate cervical screening prevalence in drug users compared to non-drug-users in Australia.

Our study linked hospital admission records of women aged 20-54 in 2000-2007 to Pap Test Register and Cancer Registry records for 19,699 with an illicit drug-related admission and 194,089 without. We designed a nested case-control study of risk of cervical intraepithelial neoplasia (CIN) 2/3 and cervical cancer and a cross-sectional study of screening prevalence in this cohort of women.

Drug users were less likely than non-users to be screened in the past 3 years (crude prevalence 47 vs 58%; prevalence ratio 0.80; 95% CI 0.78-0.81). Odds ratios (ORs) in drug users, adjusted for cervical screening history and smoking, were 1.13 (95% CI 1.04-1.23) for CIN 2/3 and 1.43 (95% CI 0.96-2.15) for cervical cancer. The adjusted ORs in each case were similar in cannabinoid users and users of other drugs.

The increased risks of CIN 2/3 and cervical cancer we observed are probably due to sex risk behaviors and their associated high risk of HPV. Interventions in drug users, such as HPV vaccination and barrier contraception and more cervical screening, might reduce the risk of cervical neoplasia.