New Study Links Obesity, Starting at Adolescence, to Endometrial Cancer Among Women Not Using Hormone Therapy

Study led by the Cancer Prevention Institute of California finds women obese over a prolonged period are at greatest risk 

FREMONT, CA (November 7, 2016) While it is well established that obesity is closely linked to endometrial cancer risk, most past findings have only looked at risk in relation to one measure of body size at a time. In this study led by the Cancer Prevention Institute of California, e-published on November 3, 2016 in the journal Cancer Causes and Control, researchers evaluated changes in obesity, beginning at adolescence, to identify lifetime risk factors that may lead to endometrial cancer. 

Researchers found that adolescent obesity contributed to endometrial cancer risk, even among women who were at a normal weight as adults. However, women who were obese over a prolonged period were at greatest risk. Further, the taller the woman, the greater the risk associated with prolonged obesity. These associations are limited to women who have not used any form of hormone therapy. Among women using hormone therapy, only greater height was associated with risk.

According to Pamela Horn-Ross, the lead researcher of this study and consulting epidemiologist with the Cancer Prevention Institute of California, “The results of this study have important implications for the future risk of endometrial cancer among girls given the widespread epidemic of obesity in our society. It will also help researchers understand discrepancies between previous studies and aid in developing targeted inventions for the prevention of endometrial cancer."

To conduct this study, researchers evaluated 88,142 female participants in the California Teachers Study (CTS) followed for more than 15 years. Participants completed a self-administered questionnaire addressing health and medical history, including hormone therapy and body size, at the time they began participation in the study group and repeated three more surveys through 2006. Only women who had not had an endometrial cancer prior to joining the study were included in this analysis. Of the study participants, 887 were diagnosed with invasive type I endometrial cancer between 1997 and 2012.

The CTS is a statewide health study of over 133,000 female current and former school teachers and school administrators that started in 1995. Along with the Cancer Prevention Institute of California, other participating research institutions are the City of Hope National Medical Center, the University of Southern California, and the University of California, Irvine. 

Other researchers that participated in the study are Alison J. Canchola, Peggy Reynolds,  and David O. Nelson, Cancer Prevention Institute of California, Leslie Bernstein and James V. Lacey Jr., City of Hope, and Dennis Deapen and Eunjung Lee, University of Southern California.

About the Cancer Prevention Institute of California
The Cancer Prevention Institute of California is a nonprofit organization dedicated to preventing cancer and to reducing its burden where it cannot yet be prevented. We are the only freestanding research institution working solely to prevent cancer using extensive population data. Our researchers study a wide range of cancer risk factors, such as racial/ethnic background, socioeconomic status, age, occupation, gender, genetic predisposition, geographic location, environment and lifestyle to determine how these factors affect frequency, distribution and types of cancers. For more information, visit the CPIC website at

Media Contact: 
Donna Lock, 510-608-5160 |


© Cancer Prevention Institute of California