A cervical cancer screening interval of 5 years or longer may be safe for women with one or more negative cotests using the high-risk human papillomavirus (HPV) test and cervical cytology, according to the results of a large observational study.

The findings also suggest that one or two negative HPV tests, regardless of cytology, may be enough to extend the screening interval, the researchers noted.

The risk of invasive cervical cancer, cervical intraepithelial neoplasia (CIN) grade 3, and adenocarcinoma in situ decreased with each round of cotesting performed, with a greater absolute decrease in risk seen between the first and second round of testing than between the second and third round, Philip E. Castle, PhD , of Albert Einstein College of Medicine, N.Y., and his colleagues reported (Ann Intern Med. 2017. doi: 10.7326/M17-1609 ).

The 5-year risk decreased with each successive HPV-negative and cytology-negative result, falling from 0.098% in the first cotesting round, to 0.052% in the second round, and 0.035% in the third round. The 5-year risks were similar with an HPV-negative cotest result, regardless of the outcome of cytology: 0.114%, 0.061%, and 0.041%.

The results are based on data from more than 990,000 women in the Kaiser Permanente Northern California health care system who had one or more cotests from 2003 to 2014.

These findings come as the U.S. Preventive Services Task Force (USPSTF) has issued draft recommendations that would call for either HPV testing alone every 5 years starting at age 30 years or cytology every 3 years, but no cotesting. The American College of Obstetricians and Gynecologists currently recommends cotesting with cytology and HPV testing every 5 years or cytology alone every 3 years in women aged 30-65 years ( Obstet Gynecol. 2016;128[4]:e111-30 ).

The study was partially funded by the National Cancer Institute. Some of the researchers are employees of the National Cancer Institute. The researchers reported receiving cervical screening tests and diagnostics at reduced or no cost from Roche, BD Biosciences, Cepheid, Arbor Vita, and Hologic.