Risk Factors for Epithelial Ovarian Tumours of Borderline Malignancy

Abstract

R and Mangioni C. Risk factors for epithelial ovarian tumours of borderline malignancy. 1991; 20: 871-877. 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 (CD: 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 (X 2 , trend = 12.70, p<0.001). This study provides epidemiological evidence of a pathogenetic continuum between borderline and invasive ovarian tumours. International Journal of EpidemiologyBorderline ovarian tumours amount to about 10-15% of malignant ovarian tumours in the epithelial category. They show many histological characteristics of malignancy, including increased mitotic activity, nuclear abnormalities, multilayering of cells, but do not invade the ovarian stroma, the frequency of their extraovarian spread is low and their clinical course is characterized by low malignancy and high survival rates.1 ' 2Descriptive epidemiological studies and clinical series have shown that borderline ovarian tumours are relatively more common in younger women than invasive carcinomas, and their incidence, as for malignant epithelial neoplasia, is lower in non-white than in white women. 3 Further, the few available analytical epidemiological data suggest that borderline neoplasia may share risk factors (e.g. parity or oral contraceptive use) with invasive cancer, 4 -5 but no association was found between borderline ovarian tumours and a family history of ovarian cancer (a recognized risk factor for invasive tumours) 5 " 8 in two case-control studies conducted in the US. To obtain further information on the epidemiology of borderline ovarian tumours, we considered data from a case-control study conducted in the greater Milan area, Northern Italy. SUBJECTS AND METHODSSince 1986 we have been conducting a case-control study of borderline ovarian tumours. Trained interviewers identified and questioned women with borderline ovarian tumour and control subjects. All interviews were conducted in hospital.Cases were women aged less than 65 years with histologically-confirmed diagnosis of bor...

The management of borderline epithelial tumors of the ovary

“…Several studies provide evidence of similarities between the etiology of EOC and BTO (17,18) . In particular the protective effects of parity and the use of oral contraceptives are in concordance with the “incessant ovulation” theory regarding the pathogenesis of EOC (9,19,20) .…”

Current Understanding of Risk Factors for Ovarian Cancer

“…A positive association between age at natural menopause and EOC risk appears in several case-control studies, with risk estimates across studies from 1.5 to 2.9 for the oldest menopause category compared with younger referents [17][18][19] supporting the incessant ovulation hypothesis but contradicting a gonadotropin hypothesis. Late age at menopause also was associated with an increased risk of BOT in some [19,21,22] but not other studies [20].…”

“…An OR for EOC of 0.32 (95% CI 0.18-0.56) was reported among women who had given birth to five or more children compared to nulliparous. Parous women also seem to be at reduced risks of borderline ovarian tumor (BOT), although the protection seems to be weaker than that seen for EOC [12,[19][20][21][22][23]. Histology-specific risk estimates indicate a protective effect of parity against all types of EOC and BOT [13,19] except possibly for mucinous tumors, where positive, inverse [10,13,19,20] and absent associations have been reported [23].…”

“…The use of OCs appears to have no effect on mucinous cancers in some studies [11,13,23,34]. For BOT, OCs also appear to reduce risk when separate analysis was performed [20][21][22][23]34]. • Suggesting a co-effect of NSAIDs and OCPs, a population-based casecontrol study from Wisconsin and Massachusetts found an inverse association of ever users of NSAIDs in women that never used oral contraceptives with OR = 0.58 (95%CI 0.42-0.80) but not for women that ever used oral contraceptives (OR = 0.98, 95%CI 0.71-1.35).…”

Epidemiology of occupational and environmental risk factors related to ovarian cancer

“…Parity and maternal age at first birth (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27), use of combined oral contraceptives (8,24,(28)(29)(30)(31)(32)(33)(34), and early age at menopause (17,20,35) seem to be protective. Data on hormonal replacement therapy are inconsistent (12).…”