Objectives: The prognostic impact of risk factors for ovarian cancer development is sparsely explored, but previous sterilisation has been shown to have a negative impact on survival.
Methods: Ovarian cancer cases were from the Danish MALOVA study. Information on previous pelvic surgery as well as reproductive variables was obtained from a personal interview conducted closely after primary surgery. Cox regression models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for ovarian cancer specific death in relation to previous pelvic surgery and reproductive variables including lifetime number of ovulation years.
Results: A total of 295 women with Stage III ovarian carcinomas were identified and followed to death or for a median of 7.3 years (range 5.4-9.5 years). Previously sterilised or hysterectomised women seemed to have a slightly decreased risk of ovarian cancer death (HR = 0.62; 95% CI: 0.36-1.08 and HR = 0.82; 95% CI: 0.55-1.21), although none of these associations reached statistical significance. The prognostic impacts of the individual reproductive variables followed the same pattern as the impact of the variables on ovarian cancer development, although significance was only reached for age at menarche (HR = 0.91 per year; 95% CI: 0.84-0.99). By accumulation of the possible minor effects of the reproductive variables in calculation of the total lifetime number of ovulation years, we found that survival decreased significantly with increasing number of ovulations (HR = 1.53 per 10 years; 95% CI: 1.09-2.14).
Conclusion: Increasing lifetime number of ovulations was a negative prognostic factor for ovarian cancer specific survival. Previous sterilisation or hysterectomy seemed to be associated with improved survival.