A follow-up study of women who originally participated in a large Australian population based case-control study was conducted to investigate the role of clinical, lifestyle, personal and dietary factors in the survival of women with ovarian cancer. The population comprised 822 women with histologically confirmed epithelial ovarian cancer, diagnosed between 1990-1993 in three Australia states; Queensland, Victoria and New South Wales. Clinical and pathological information was collected from medical records and histological diagnoses were reviewed centrally by a single pathologist in each state. The dietary data were gathered using a semi-quantitative food frequency questionnaire (119 food items), with women being asked to report their usual intake over the year prior to the onset of any symptoms they related to their diagnosis. Lifestyle and other personal information were collected in a standardized face-to-face interview. Deaths in the cohort were identified using state based cancer registries and the Australian NDI. Crude 5-year survival probabilities were estimated using the Kaplan-Meier technique, and adjusted hazard ratios and 95% confidence limits were obtained from Cox regression models.
The findings are based on 676 women with invasive epithelial ovarian cancer, because there was a marked difference in crude survival according to tumour invasiveness, with only two of 146 women with borderline tumours dying during the follow-up period. Of the 676 women with invasive disease, 419 died from ovarian cancer, a crude 5-year survival of 44%. In multivariate analysis of clinical and pathologic prognostic factors increasing tumour stage (FIGO), older age at diagnosis, high-grade tumours and to a lesser extent ascites at primary surgery and residual disease all had clear, independent, adverse effects on survival in these women. This set of prognostic variables explained 39% of the variation in outcome.
Among the dietary factors examined, inverse associations were observed for those who reported higher intake of vegetables in general, and cruciferous vegetables in particular (HR 0.75; 95% CI 0.57-0.98, p-value for trend 0.03) and among women in the upper third of intake of Vitamin E. Inverse associations with mortality were also seen with protein, red meat, and white meat and modest positive trends (maximum 30% mortality excess) with lactose, calcium and dairy products. Tobacco smoking, both current and former, was associated with a somewhat worse mortality. Women consuming high amounts of coffee were also at increased risk of early death (4 or more cups per day HR=1.44; 95% CI 0.98- 2.11), although there was no trend across coffee drinking groups. BMI was not associated with survival, except perhaps for the very thinnest women (BMI <20) who appeared to do somewhat better. Preliminary exploration of the influence of reproductive factors found a small inverse association among women who had used oral contraceptives. This effect was strongest in women who had taken oral contraceptives for 24-59 months (HR 0.70), however the 95% CI just included 1.0. There was also a modest benefit for women who had breastfed and for those who had taken hormone replacement therapy.
Although much remains to be learned about the influence of non-clinical factors after a diagnosis of ovarian cancer, this study suggests the possibility that a diet high in vegetable intake may help improve outcomes and that a number of lifestyle factors, known to negatively influence mortality in other cancers, may also influence mortality from ovarian cancer.