Risk of Cervical Cancer May be Slightly Elevated for Users of Injectables

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During the 1970s and part of the 1980s in Mexico and Thailand interviews were conducted with 1217 women who had cervical carcinoma in situ and 8956 controls to examine the link between the injectable contraceptive depot medroxyprogesterone acetate (DMPA) and cervical cancer. Women with cervical cancer were more likely than controls to have ever used DMPA (23% vs. 15%). When researchers controlled for age hospital number of pregnancies ever use of oral contraceptives and frequency of Pap smears ever users of DMPA had a 43% higher risk of cervical cancer than did nonusers. Ever users of DMPA who had no symptoms at diagnosis were more likely to have cervical cancer than nonusers (relative risk [RR] = 1.92; p < 0.05). Symptomatic ever users of DMPA were more likely to have cervical cancer than nonusers (RR = 1.25; p < 0.05). As duration of DMPA use increased so did the probability of cervical cancer. The increase was greater among women asymptomatic at diagnosis. Asymptomatic women who had used DMPA for 5 years faced an increased RR of 3.07. The comparable RR for symptomatic women was 1.77. Women who first used DMPA 5-10 years before the study were 2.19 times more likely to have symptomatic cervical cancer than nonusers. While those who first used DMPA more than 10 years before the study were not much more likely to have symptomatic cervical cancer. Symptomatic women who used DMPA for more than 5 years but had stopped using it 1-5 years before the study were 2.06 times more likely to have cervical cancer than nonusers. The risk was not significant for women who had used DMPA for more than 5 years but who had last used it more than 5 years before the study. Women who did not have a Pap smear were more likely to have symptomatic cervical cancer than those who did (RR 1.3 vs. 1.1).