Comparative study of the effects of a progestogen-only pill containing desogestrel and an intrauterine contraceptive device in lactating women. Bjarnadottir RI, Gottfredsdottir H, Sigurdardottir K, et al. Br J Obstet Gynaecol 2001; 108: 1174-1180

as age at first intercourse and age at first pregnancy. An association between increasing duration of OC use and risk of cervical cancer and carcinoma in situ was identified. No association was found with age at first OC use. Use of OC for less than 5 years was not associated with increased risk of cervical neoplasia. Women with a total of 5 to 9 years of OC use had almost three times the risk of cervical neoplasia (odds ratio 2.82, 95% CI 1.46–5.42). Those women with more than 10 years of OC use had four times the risk of cervical neoplasia (odds ratio 4.03, 95% CI 2.09–7.79). The increased risk of cervical neoplasia appeared to persist for as long as 15 years after discontinuing OC. Use of OC itself did not appear to increase the chance of infection with HPV. This study would appear to confirm a plausible association between OC and cervical cancer. Researchers focused on women deemed at high risk of developing cervical cancer because they were HPV-positive. These findings cannot therefore be explained away by higher risk sexual activity as has been done previously. It must be acknowledged, however, that there are a number of areas where bias may have been introduced. Recall bias is acknowledged in that women may not have accurately recalled previous use of hormonal contraceptive methods and some may have used progestogen-only methods. Only one HPV test was carried out, but persistence of HPV is thought to be an important factor in carcinogenesis. This study therefore could not distinguish those women who had only transient infection from those with persistent HPV. Although the findings are relevant for women in the developed world, most of the women in the study (apart from those from Spain) lived in countries in which there are no national cervical screening programmes. This study serves to underline the importance of attending for regular cervical screening smears. In this context, these findings need not affect women’s contraceptive or reproductive choices. In discussion with women in the UK, it is important to stress the much lower rates of cervical cancer here, in addition to the many benefits of OC use and attending for routine cervical screening.