Abstract

In our article on oral contraceptives (OCs) we state that ‘oral contraceptives increase the risk of breast cancer with long-term use but reduce the risk of endometrial and ovarian cancer’. Some commentators have questioned the breast cancer risk. The UK National Case-Control (UKNCC) study, which looked at oral contraceptive use in women with breast cancer diagnosed before age 36, found a trend for increased risk associated with duration of use.¹ ‘The simplest and most plausible explanation’, say the authors of the study, ‘must be that there is a substantial causal relation between prolonged use and breast cancer in young women.’ The increased risk seems to be associated particularly with OC use before the first full-term pregnancy.² Several studies found no excess risk in OC users aged 45 or over, few of whom had taken the pill before their first pregnancy.^3–5 In the UKNCC study the relative risk of breast cancer was 1.43 after 4–8 years’ use and 1.74 after more than 8 years’ use. In broad terms this means that three women in 1000 who use oral contraceptives for 4 or more years might be expected to be under treatment for breast cancer by age 36, compared with two per 1000 non-users.