DISEASE CHARACTERISTICS:

• Healthy women with ≥ 18% lifetime risk for breast cancer as evidenced by the following:

  • Documentation from a genetic counselor of a known familial breast cancer susceptibility mutation
  • Claus model risk of ≥18%
  • Predicted probability of BRCA1/2 mutation > 25% based on the Myriad model
  • Documentation of a known mutation in a family member such that the Mendelian probability of a BRCA1/2 mutation would be >25%
  • History of lobular carcinoma in situ
• No prior prophylactic mastectomy
• Leisure-time exercise energy expenditure of ≤ 500 kcal/week over the past 6 months
• Hormone receptor status not specified

PATIENT CHARACTERISTICS:

• Premenopausal
• Menstrual cycles 25-32 days in length
• Intact ovaries and uterus
• Gynecologic age (defined as participant's current age minus the age at which she started menstruating) of at least 4 years
• Body mass index 21-50
• No history of menstrual difficulties
• No history of physician-diagnosed gynecological disease (e.g., fibroids, endometriosis, or polycystic ovary syndrome)
• Not pregnant
• Not planning to become pregnant during the study period
• No medical conditions or medications that would prohibit participation in aerobic exercise or would negatively impact the study
• No history of cancer, except nonmelanoma skin cancers, and in situ cervical cancers
• No eating disorders (e.g., bulimia or binge-eating disorder)
• At least one year since prior smoking
• Not planning to move away from the area during the period of the study
• No concurrent participation in any weight loss programs

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 3 months since prior hormonal contraception
• Must use effective non-hormonal contraception unless participant has undergone prior tubal ligation
• Consumes no more than 7 alcoholic beverages per week