Physical Activity, Diet and Menarche in a Multiethnic Cohort

Institution: University of Southern California
Investigator(s): Carol  Koprowski , Ph.D., R.D. -
Award Cycle: 1997 (Cycle III) Grant #: 3FB-0065 Award: $75,546
Award Type: Postdoctoral Fellowship
Research Priorities
Etiology>Hormones and nutrition: understanding the modern woman's lifestyle



Initial Award Abstract (1997)
Breast cancer is the most commonly diagnosed cancer in women. While the exact cause (or causes) of breast cancer remains unknown, certain features or aspects of a woman’s life appear to increase the chance that she may develop breast cancer during her lifetime. A woman who has her first menstrual period at an early age is more likely to be diagnosed with breast cancer than a woman who has her first menstrual period at a later age. Women who produce an egg during each menstrual cycle are also more likely to be diagnosed with breast cancer compared to women who do not produce an egg at each menstrual cycle.

The primary purpose of this study is to examine certain behaviors, specifically what a woman eats and her amount of physical activity, and how these behaviors relate to when she had her first menstrual period and whether she produced an egg during her menstrual cycles after she began having periods. A group of almost 1400 girls of different ethnic backgrounds were asked questions about their physical activity and the types and amounts of foods they ate. These girls were initially in the 4th through 7th grades and participated in a study that lasted for four years. Each girl was asked about her diet and physical activity up to five times during the course of the study. A total of 180 girls were also tested to see if they produced an egg during menstrual cycles. This information will be analyzed to determine if diet and physical activity are related to a woman’s age at her first menstrual period or whether or not she is likely to produce an egg during her menstrual cycles.

If a relationship is found between physical activity, diet and a woman’s age at her first menstrual period or whether or not she produces an egg during her menstrual cycles, then more information will be available to help explain why some women are more likely to be diagnosed with breast cancer. Also, a woman may be able to change her behavior and possibly lower her chances of being diagnosed with breast cancer. For example, if physical activity decreases the chances that a woman will produce an egg during her menstrual cycles, then encouraging a woman to participate in regular physical activity may be a simple and effective means of lowering her chances of being diagnosed with breast cancer during her lifetime.


Final Report (1999)
The purpose of this study is to examine the relationship between diet, physical activity and when a woman has her first menstrual period (menarche). The exact cause (or causes) of breast cancer remains unknown; however, certain aspects of a woman's life appear to increase her chances that she will develop breast cancer during her lifetime. A woman who has her first menstrual period at an early age is more likely to be diagnosed with breast cancer than a woman who has her first menstrual period at a later age.

Approximately 1400 girls of different ethnic backgrounds provided information about their diet and physical activity patterns. These girls were initially in the 4th through 7th grades and participated in a study that lasted four years. Each girl was asked about her diet and physical activity habits up to five times during the study. Of the almost 1400 girls who participated in the study, a total of 751 girls provided information on diet and physical activity at least one time prior to experiencing their first menstrual periods.

The girls in this study participated in an average of one hour of physical activity per day (or seven hours per week). The results of this study indicate that girls who spent more hours in physical activity (13 or more hours per week) were more likely to have their first menstrual periods at later ages when compared to girls who spent fewer hours performing physical activity (less than five hours per week). The results of this project demonstrate the importance of lifestyle factors, such as physical activity, as they relate to risk factors associated with breast cancer.

Current analyses are examining the relationship between diet, physical activity and ovulatory status of a menstrual cycle (i.e. was an egg released during the menstrual cycle). These analyses involve a subset (n=209) of the original cohort who provided at a urine sample on a specific day of the menstrual cycle. Hormone levels were measured and this information was used to determine whether or not ovulation occurred during that particular menstrual cycle. A woman who has more ovulatory cycles during her lifetime is at increased risk of breast cancer. The results of these analyses will provide information on how lifestyle factors, such as diet and physical activity, influence ovulation.
Diet, body size and menarche in a multiethnic cohort.
Periodical:British Journal of Cancer
Index Medicus: Br J Cancer
Authors: Koprowski CM, Ross RK, Mack WJ, Henderson BE, and Bernstein L.
Yr: 1999 Vol: 79 Nbr: 11/12 Abs: Pg:1907-1911
Ability of young women to recall past body size and age at menarche
Periodical:Obesity Research
Index Medicus:
Authors: Koprowski CM, Coates RJ, and Bernstein L.
Yr: 2001 Vol: 9 Nbr: 8 Abs: Pg:478-485