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Rapid decline in ovarian cancer rates coincides with decreased hormone therapy use
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The decrease in ovarian cancer rates in the United States accelerated after a marked decline in use of hormone therapy nationwide, study results showed.
“To the best of our knowledge, we do not know of any other calendar-period changes with a similar temporal relationship,” Hannah P. Yang, PhD, ScM, staff scientist at the NCI, told HemOnc Today. “While cause-and-effect relationships cannot be established in our descriptive epidemiological analysis, we can report the compelling temporal association between a precipitous decline in menopausal hormone therapy and a sharp drop in ovarian cancer incidence.”
Hannah P. Yang
The Women’s Health Initiative released a report in 2002 suggesting hormone therapy was associated with increased risk for adverse health effects. After the WHI released its report, the use of hormone therapy decreased significantly. Breast cancer rates subsequently declined, but an analysis of ovarian cancer rates since the report’s release had not been performed, according to researchers.
Yang and colleagues set out to assess whether ovarian cancer incidence rates changed after 2002. They used the North American Association of Central Cancer Registries database to identify 171,142 incident ovarian cancers between 1995 and 2008.
Among women aged 50 years and older, age-standardized ovarian cancer incidence declined by 0.8% per year (95% CI, -1.8 to -0.5%) prior to the release of the WHI report in 2002. After the report’s release, the incidence rate decreased by 2.4% per year (95% CI, -2.5% to -2.2%), study results showed.
“[Age-period-cohort] models confirmed an accelerated decline in ovarian cancer incidence after the WHI report, adjusted for age and birth cohort effects,” the researchers wrote.
The most significant decrease in ovarian cancer rates was observed among white women, those who were aged 50 to 69 years, and those who resided in regions with the highest hormone therapy prescription frequency.
Ovarian cancer incidence decreased steadily during the entire study period among women aged 50 years and younger (-2.2% per year; 95% CI, -2.5 to 1.8 per year).
“Understanding exposures within at-risk populations is useful in considering options for cancer prevention and control, which are particularly critical for tumors that are difficult to treat, such as ovarian cancer,” Yang said. “Notably, exposures that produce modest effects for individuals may nonetheless have public health implications when considered across large populations (all postmenopausal women in the US). Better understanding of ovarian carcinogenesis may help prevent the development of this disease and possibly have a major public health impact. Our analysis contributes in these areas.”
These data have clinical importance for monitoring ovarian cancer rates but do not provide the basis for making complex, individual decisions about short-term hormone therapy use to decrease menopausal symptoms, Yang said.
Hannah P. Yang, PhD, ScM, can be reached at 6120 Executive Blvd., EPS/ 5030, Rockville, MD 20852; email: yanghan@mail.nih.gov.
Disclosure:Yang reports no relevant financial disclosures.
Perspective
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Ritu Salani, MD, MBA
Ovarian cancer continues to remain a common cause of cancer mortality in women in the United States. This fact remains despite modest improvements in both surgical and therapeutic options, and it may be attributed to diagnosis in advanced stages. As the identification of successful screening tools has continued to elude us, efforts focusing on prevention have continued to develop. One example includes favorable outcomes following risk-reducing surgery for women with genetic predisposition (eg, BRCA mutation carriers).
Yang and colleagues evaluated ovarian cancer incidences in relation to time periods before and after the Women’s Health Initiative, after which the use of hormone replacement therapy declined significantly. The authors report that although ovarian cancer incidence had declined prior to 2002 by 0.8% per year, there was an accelerated decline (2.4% per year) after 2002, suggesting a temporal association between hormone use and ovarian cancer in women aged 50 to 69 years.
It is important to note that ovarian cancer has been established as a hormonally sensitive cancer, demonstrated by the protective nature of the use of oral contraceptive pills. Whether the use of hormones in postmenopausal women is truly a causative factor for the development of ovarian cancer requires further investigation; however, the decline in incidence is provocative and consistent with the breast cancer literature. Regardless, these findings highlight the intimate relationship between hormones and ovarian cancer and should be considered when counseling patients.
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