Risk factors for epithelial ovarian tumours of borderline malignancy

Abstract

A case-control study was conducted on 91 cases with histologically-confirmed borderline ovarian tumours and 237 control subjects in hospital for acute non-gynaecological, hormonal or neoplastic disease. Women reporting three or more births, compared to nulliparae, had a relative risk (RR) estimate of 0.6, but this finding was not statistically significant (95% confidence interval (CI): 0.2-1.4). The risk of borderline tumours increased, although not significantly, with later age at first birth: compared to women reporting first birth at age 24 or before, the RRs were 1.3 and 1.7 in those reporting respectively their first birth at age 25-29 and 30 years or more. No significant relationship emerged between borderline ovarian cancer and age at menarche, menopausal status and lifelong menstrual pattern. Cases tended to report a later age at menopause than controls, but the trend in risk was not statistically significant. Nine cases (9.9%) and 68 controls (24.9%) reported oral contraceptive use: compared with never users the multivariate RR for ever users was 0.3, and the risk dropped with duration of use to 0.2 in users for two years or more (chi 2 (1) trend = 12.70, p less than 0.001). This study provides epidemiological evidence of a pathogenetic continuum between borderline and invasive ovarian tumours.

PIP: Researchers compared 91 women with histologically confirmed borderline ovarian tumors at the University of Milan with 237 women (controls) admitted to Ospedale Maggiore in Milan, Italy for acute nongynecological, nonhormonal and nonneoplastic conditions to learn more about the epidemiology of borderline ovarian tumors. Oral contraceptives (OC) users had about a 70% lower risk of borderline ovarian tumors than nonOC users (relative risk ¿RR¿=0.3). In fact, the RR fell significantly to 0.2 for women who used OCs for at least 2 years (p.001). Further the risk of borderline ovarian tumors increased significantly as the age of women at the time of 1st birth increased (RR=1.8 for 25-29 year olds and RR=2.5 for =or 30 year olds; p=.02 [Mantel-Haenszel technique]). Women who experienced at least 1 induced abortion were less likely to have borderline ovarian tumors than those who had never experienced an induced abortion (RR=0.2). This may be because these women were of high fertility which agreed with the finding of lower risk in women of parity =or 3 (RR=0.7; p=0.23 insignificant). A higher risk was associated with late age at menopause, but the association was insignificant (RR=around 50 years old). Since the sample size was small due to the rarity of borderline ovarian tumors, one should interpret these results which caution. Nevertheless they supported the incessant ovulation hypothesis in ovarian carcinogenesis where the more exposure to ovulation or ovulatory cycles the greater the chance of ovarian neoplasms. Therefore they suggested an epidemiological continuum between various grades of malignancy of epithelial ovarian neoplasms.