By Bianca Nogrady
Cervical cancer screening until a woman is in her 70s still achieves reductions in cancer risk but a woman with a negative human papillomavirus (HPV) test at age 55 years has a low lifetime risk of cervical cancer, modelling suggests.
In the study, published in the Lancet Oncology, Canadian researchers modelled the impact of different ages of screening cessation for cervical cancer on lifetime risk of the disease.
This showed that among women who had not been vaccinated against HPV and who had never been screened there was a one in 45 lifetime risk of cervical cancer. Among women with typical adherence to cytology screening from age 25 to 55 years, the lifetime risk was one in 138, and continuing cytological screening until age 70 years further reduced the lifetime risk to one in 160.
Among women who had been screened with cytology every three years between the ages of 25 and 69 years but who had not received the HPV vaccine the lifetime risk was one in 532.
‘This result suggests a substantial part of the reduction in the cumulative lifetime risk at older ages is due to screening before the age of 55 years (compared with no screening),’ the researchers wrote.
Looking at the effect of different ages for screening exit, the researchers found incremental reductions in later cervical cancer incidence up until 75 years of age. For example, a woman who stopped cytological screening at 55 years had about twice the five-year cervical cancer risk at 70 to 85 years compared with a woman who continued cytological screening.
The lowest lifetime risk of cervical cancer (one in 9550) was in women who continued cytology screening until 70 years, then had a negative cytology and HPV exit test.
Professor Karen Canfell, Director of Research at Cancer Council NSW, told Medicine Today that the question of what was the best age to discharge women from cervical screening was important.
‘It’s true to say that older women who test HPV negative are at much lower risk of developing cervical cancer but our own analysis, which supported the new HPV-based national Cervical Screening Program in Australia, did show that there are still some incremental benefits,’ she said.
The new Australian cervical cancer screening guidelines recommend that women aged 70 to 74 years whose exit test is negative for oncogenic HPV can be discharged from the screening program.
Lancet Oncol 2018; http://dx.doi.org/10.1016/S1470-2045(18)30536-9.