Association of oral contraceptive use and human papillomaviruses in invasive cervical cancers.

In a study of 197 cases of histologically confirmed invasive cervical cancer, 61% of biopsies were positive for human papillomavirus (HPV) DNA by Southern or dot-blot hybridization. An association between detection of HPV DNA and oral contraceptive use was observed when HPV-positive and -negative cases were compared. Women reporting recent or long-term (greater than 4 yrs) oral contraceptive use were at 2.3 and 2.9-fold increased risks of HPV positivity, respectively. An increased risk of HPV positivity was also associated with formal education and with urban residence, while long-term smoking was negatively associated with HPV detection. A non-significant trend of increasing risk of HPV positivity with increasing number of sexual partners of the women and of the male partners of monogamous women was observed. Detection of HPV DNA was not associated with other cervical cancer risk factors examined, including age at first coitus, number of pregnancies, and Pap smear screening history. Our findings suggest either an interaction between HPV infection and oral contraceptive use in the genesis of cervical cancer or an increased expression of HPV genome in neoplasms of oral contraceptive users. These observations also support a multifactorial model of cervical cancer causation.