Risk of second malignant neoplasms following female genital tract cancers in New South Wales (Australia), 1972-91

Data from the New South Wales (NSW) Central Cancer Registry for 1972-91 were examined to determine the risk of a second primary cancer following an initial invasive cancer of the cervix uteri (ICD-9 180), corpus uteri (ICD-9 182), ovary (ICD-9 183) or 'other female genital organs' (ICD-9 184). Expected numbers of cancers were obtained by assuming that women with a cancer of the female genital tract experienced the same cancer incidence as the female population of NSW as a whole. The relative risk (RR) of a second primary cancer was the ratio of observed to expected numbers of second cancers, excluding those of the female genital tract. Following cervical cancer, significantly increased risks were found for cancer of the larynx (RR= 7.43), lung (RR = 3.64), bladder (RR = 3.36) and for all tobacco-related sites (excluding cervix and bladder) grouped together (RR = 2.54). A nonsignificant excess of anal cancer (RR = 4.23) was also seen. After an initial cancer of the corpus uteri significantly increased risks were found for colorectal (RR = 1.35), breast (RR = 1.36) and bladder cancers (RR = 1.95). The excess of colorectal cancer bordered on significance (RR = 1.43) but there was no increased risk of breast cancer (RR = 1.02) after ovarian cancer. The data illustrate the need for surveillance of women with cervical cancer for further tobacco-related cancers, and the risk of treatment-initiated neoplasms.