Breast Cancer Survivors Under 50 Years Old Are at High Risk for Ovarian Cancer

Some factors that lead to the development of breast cancer are similar to those responsible for the development of ovarian cancer, say the authors of a new study. Consequently, women who survive breast cancer, especially those under the age of 50 years, should be aware that they are at higher risk for ovarian cancer.

The study was presented at the 30th annual meeting of the Society of Gynecologic Oncologists. Authors included: Wendy R. Brewster, MD, Argyrios Ziogas, PhD, Thomas H. Taylor, PhD, Krishnansu Tewari, MD, Alberto Manetta, MD, and Hoda Anton-Culver, PhD, all from The Chao Family Comprehensive Cancer Center, University of California-Irvine Medical Center and the Division of Epidemiology and Biostatistics, University of California-Irvine.

Ovarian and Breast Cancer Share Risk Factors

Breast cancer is the most frequently diagnosed cancer among US women. In 1998 alone, an estimated 180,000 new cases of breast cancer were diagnosed and 43,500 women died of the disease. In contrast, ovarian cancer accounts for only 4% of all cancers in women. In 1998, an estimated 25,400 women were newly diagnosed with the disease and 14,500 women died as a result. Ovarian cancer has been shown to share many of the same risk factors associated with breast cancer.

The University of California-Irvine research team believed that the environmental, behavioral, and genetic interactions that influence the breast cancer disease process would also influence the development of subsequent malignancies, specifically, ovarian cancer. Therefore, they hypothesized that breast cancer survivors might be susceptible for developing ovarian cancer and their study set out to estimate that risk.

Study Methodology

The Surveillance, Epidemiology and End Results (SEER) database of the National Cancer Institute, Division of Cancer Prevention and Control Surveillance Program provided data for the study.

Women 15 to 80 years of age who had been diagnosed with breast cancer between 1980 and 1990 were identified based on their unique patient registration numbers. The same registration numbers also designated all other cancers found in these patients, and codes were programmed into the computer to distinguish the women who had developed ovarian cancer after being diagnosed with breast cancer. The 120,380 subjects selected for the study were categorized by age at diagnosis, stage of breast cancer at diagnosis, and ethnic/racial background.

Study Results

Of the 120,380 subjects, 104,617 (87%) had breast cancer as their only malignancy. The remaining 15,763 women (13%) reported developing at least one other malignancy in the 10-year period after their breast cancer. Other significant findings included the following:

Of the women with more than one malignancy, 478 were diagnosed with ovarian cancer. Of that group, 417 acquired the disease subsequent to breast cancer; 61 had ovarian cancer diagnosed as the third or later primary malignancy.

Women diagnosed with breast cancer between the ages of 15 and 39 years showed a significantly elevated risk for developing ovarian cancer. A significant but modest risk was identified among women diagnosed with breast cancer between the ages of 40 and 50 years. For women older than 50 years, only those diagnosed at ages 71 to 80 years demonstrated a significant risk for ovarian cancer.

The highest risk for ovarian cancer was found among women of Hispanic and Asian descent who had been diagnosed with breast cancer before the age of 50 years. African-American women had the next highest risk, and non-Hispanic whites had the lowest relative risk of the groups studied.

Women under 50 years of age with a diagnosis of stage I/II breast cancer had a higher risk for ovarian cancer than did those with in situ or more advanced cancers diagnosed at a similar age. Breast cancers diagnosed after age 50 years were not associated with an increased risk for ovarian cancer.

The most frequent malignancies found subsequent to breast cancer were a second breast cancer (8,194 women), cancer of the digestive system (1,716 women), respiratory tract cancer (1,109 women), and female genital tract cancer (1,181 women).