Current Gaps in Ovarian Cancer Epidemiology: The Need for New Population-Based Research

Abstract

With recent ovarian cancer screening studies showing no clinically significant mortality benefit, preventing this disease, identifying high-risk populations, and extending survival remain priorities. However, several challenges are impeding progress in ovarian cancer research. With most studies capturing exposure information from 10 or more years ago, evaluation of how changing patterns of exposures, such as new oral contraceptive formulations and increased intrauterine device use, might influence ovarian cancer risk and survival is difficult. Risk factors for ovarian cancer should be evaluated in the context of tumor histotypes, which have unique molecular features and cells of origin; this is a task that requires large collaborative studies to achieve meaningful sample sizes. Importantly, identification of novel modifiable risk factors, in addition to those currently known to reduce risk (eg, childbearing, tubal ligation, oral contraceptive use), is needed; this is not feasibly implemented at a population level. In this Commentary, we describe important gaps in knowledge and propose new approaches to advance epidemiologic research to improve ovarian cancer prevention and survival, including updated classification of tumors, collection of data on changing and novel exposures, longer follow-up on existing studies, evaluation of diverse populations, development of better risk prediction models, and collaborating prospectively with consortia to develop protocols for new studies that will allow seamless integration for future pooled analyses.

Figure 1.

Changing pattern of contraceptive use by age group may predict changes in future risk of ovarian cancer. Values represent percent of contracepting women. In 2011 to 2013, this includes the oral contraceptive pill only. In previous surveys, this includes the oral contraceptive pill and emergency contraception/morning-after pill. Asterisks represent known values; unknown values of intervening years were estimated using linear interpolation (89). IUD = intrauterine device.

Figure 2.

Changing pattern of use of low-dose menopausal hormone therapy (MHT) by age group in the aftermath of the Women’s Health Initiative trial. Data are reported as number of US office–based physician visits by women age 18 years and older in which MHT use was reported by formulation, dose, and women’s age between January 2001 and December 2009 from the National Disease and Therapeutic Index, which provides nationally representative estimates of practices of non–federally employed US office–based physicians via a physician survey. A) Trends in MHT use by formulation and age group. B) Expanded view of trends in low-dose MHT by age group. Reproduced with permission from the publisher Wolters Kluwer (50). MHT = menopausal hormone therapy.