CAUSES OF CERVICAL-CANCER IN THE PHILIPPINES - A CASE-CONTROL STUDY

Background: Among the numerous human papillomavirus (HPV) types, only types 16 and 18 have been formally classified as human carcinogens, To evaluate the associations of 33 HPV types and other risk factors with squamous cell carcinoma and adenocarcinoma of the cervix, we performe d a hospital-based, case-control study in the Philippines, Methods: Th e study included 356 case subjects who had histologically confirmed ce rvical cancer (323 incident cases of squamous cell carcinoma and 33 in cident cases of adenocarcinoma/adenosquamous carcinoma) and 381 contro l subjects. Information on risk factors was obtained by personal inter view. HPV DNA was detected in exfoliated cervical cells and biopsy spe cimens by use of a polymerase chain reaction assay. Results: HPV DNA w as detected in 93.8% of case subjects with squamous cell carcinoma and in 90.9% of case subjects with adenocarcinoma/adenosquamous carcinoma compared with 9.2% of control subjects, giving age-adjusted odds rati os of 156 (95% confidence interval [CI] = 87-280) for squamous cell ca rcinoma and 111 (95% CI = 31-392) for adenocarcinoma/adenosquamous car cinoma, Fifteen different HPV types were detected in squamous cell car cinoma, and six different HPV types were detected in adenocarcinoma/ad enosquamous carcinoma, Among HPV types other than types 16 and 18, the associations of HPV with risk of squamous cell carcinoma were stronge st for HPV45, In addition to HPV, high parity, low socioeconomic statu s, and smoking were also associated with both types of cervical cancer . Conclusions: As has been shown for squamous cell carcinoma, HPV is t he central cause of adenocarcinoma/adenosquamous carcinoma of the uter ine cervix, The observed associations of less prevalent HPV types with cervical cancer have important implications for cervical cancer preve ntion strategies.