The impact of primary HPV screening on the incidence of cervical cancer in New Zealand.
Our objective was to evaluate the impact on the incidence of cervical cancer in New Zealand of 5-yearly human papillomavirus (HPV) primary screening compared with 3-yearly cytology. Unbiased estimates of the screening test sensitivity of HPV and cytology screening, and screening coverage, were used to calculate the reduction in cervical cancer incidence obtained by current cytology screening and the new HPV screening policy. HPV screening in New Zealand is predicted to increase the incidence of cervical cancer in women being screened by 81.7% (95% CI: 38.9%-124.7%). The overall increase in the population incidence of cervical cancer in New Zealand was estimated to be 46.7% (95% CI 42.6%-50.8%), leading to about 57 more women developing cervical cancer each year. The results indicate that lengthening the screening interval concurrently with changing to HPV testing may reduce the protection from invasive cervical cancer for women. Women in New Zealand should continue to be screened by cytology every 3 years. Changes to screening policy should be carefully designed so that changes in screening effectiveness can be accurately measured.