But researchers have found that the chance of cancer from infection is dramatically magnified if the woman is also taking the oral contraceptive pill. The risks increase the longer the infected woman takes the pill; the critical time seems to be anything over five years.

The lifestyles of 12,531 women with cervical cancer were analysed and, interestingly, the other usual suspects - such as smoking, numbers of sexual partners, and barrier contraceptives - made no difference to the figures. Just as interesting, cervical screening failed to reduce the numbers.

(Source: The Lancet, 2003; 361: 1159-67).