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To determine whether a cluster of eight cancers among 572 women who had received transcervical quinacrine hydrochloride was a random occurrence or evidence of an increased risk of cancer.Retrospective cohort study using interviews and reviews of medical records. Cancer cases were evaluated using cohort analyses and space-time cluster methods.Santiago and Valdivia, Chile.Fourteen hundred ninety-two women who received transcervical quinacrine pellets for sterilization between 1977 and 1989.Age- and site-specific incidence of invasive cancers.Eight hundred two women were interviewed. From 1 to 14 years of data were available on 600 of the noninterviewed women from clinic records. During 7,852 women-years of follow-up, 17 invasive cancers were identified, compared with 11.8 expected, based on age-specific rates from the Cali, Colombia cancer registry. Five cases of cervical cancer were observed, compared with 3.96 expected. Only one other uterine cancer was observed, a leiomyosarcoma, compared with 0.2 or 0.3 other uterine cancers expected.The occurrence of an unusual cluster was confirmed, but no evidence was found of excess cancer risk associated with quinacrine pellet sterilization. However there was a single provocative observation (the leiomyosarcoma), and surveillance of the cohort is continuing.A long-term follow-up of 572 Chilean women who were sterilized by transcervical insertion of two or three 250 mg quinacrine hydrochloride pellets in 1977-81 revealed eight cases of cancer. To evaluate further the possible association between quinacrine and cancer risk, a retrospective cohort study of 1492 women from Santiago and Valdivia, Chile, who received this procedure in 1977-89 was undertaken by Family Health International (FHI). Study methods included clinic record review, interviews with traceable women or their families, hospital record review for cancer cases, and review of pathology slides for gynecologic cancers. 802 (54.6%) of cohort members were located; sufficient data were available from clinic records on another 600 women. This process revealed a total of 36 cancers; 7 were diagnosed before quinacrine sterilization, 17 were invasive carcinomas in situ of the cervix (excluded from cancer registry data), and 17 were invasive cancers diagnosed after sterilization. Of the third group of cancers--the focus of the analysis--9 were from Santiago and 8 were from Valdivia. Given the 7852 woman-years of follow-up available and the age-specific rates from the Cali cancer registry, 11.82 new cancer cases (9.15 in Santiago and 2.67 in Valdivia) would be expectable. Most common were breast and cervical cancers (5 cases each). The observed/expected ratio was 1.64 for breast cancer and 1.26 for cervical cancer; no temporal clustering was found for either cancer. Of greatest concern was the single case of uterine leiomyosarcoma; US cancer registries suggest that only 0.08-0.15 cases are expectable. Cluster analysis revealed an unusual occurrence of cancers in Valdivia in 1985-87. Although the present study lacked sufficient power or cases to determine whether transcervically administered quinacrine is or is not carcinogenic, further evaluation is warranted and FHI plans to conduct a similar study in Vietnam. |
