White Button Mushroom Extract in Preventing the Recurrence of Breast Cancer in Postmenopausal Breast Cancer Survivors

DISEASE CHARACTERISTICS:

* Meets 1 of the following criteria:

  * Prior diagnosis of infiltrating carcinoma of the breast ≥ 5 years prior to study entry
  * Prior diagnosis of ductal carcinoma in situ
* No evidence of disease
* Completed all cancer therapy, with the exception of reconstructive surgery, at least 6 months prior to study entry
* Meets one of the following criteria:

  * Normal mammogram within 1 year of study entry
  * Underwent bilateral mastectomy and has been in remission for 5 years, as documented by an oncologist
* Hormone receptor status not specified

PATIENT CHARACTERISTICS:

* ECOG performance status 0-1
* WBC ≥ 3,500/mm³
* ANC ≥ 1,500/mm³
* Platelet count ≥ 100,000/mm³
* Hemoglobin ≥ 9.0 g/dL
* Postmenopausal, defined as any of the following:

  * Continuous absence of menstruation for 12+ months
  * Status post bilateral oophorectomy
  * Status post hysterectomy with follicle-stimulating hormone in menopausal range
* Creatinine ≤ 1.5 times upper limit of normal (ULN) or less
* Total bilirubin ≤ 1.5 times ULN
* AST and ALT \< 2 times ULN
* No allergy to mushrooms
* No personal history of any invasive cancer, other than breast cancer, or squamous cell or basal cell skin cancer
* No osteoporosis, defined as a bone-mineral density T-score of \< -2.5 on dual-energy x-ray absorptiometry scan
* No major systemic infections or other major medical illnesses of the cardiovascular, respiratory, or digestive system

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* More than 3 months since prior and no concurrent hormone-modifying medications, including any of the following:

  * Oral contraceptives
  * Hormone replacement
  * Selective estrogen receptor modifiers
  * Other aromatase inhibitors
  * Gonadotropic-releasing hormone modifiers
* At least 1 month since prior and no other concurrent mushroom extracts or DHEA as a dietary supplement
* No concurrent therapy, except continued medications for unrelated illness that are not excluded, and necessary medications for unrelated acute illnesses that may occur during the study (e.g., cold, flu, or infection)
* No more than 3 concurrent servings per week of the following foods:

  * Flaxseeds and flaxseed meal
  * High-energy bars or diet bars containing soy or soy protein
  * Liquid-nutrition drinks containing soy or soy protein (e.g., Odwalla Future Shake or Ensure Plus)
  * Miso soup
  * Natto
  * Packaged mixed dishes with soy or tofu (e.g., lasagna, burritos, or stir-fry)
  * Cooked soybeans or edamame (i.e., green soybeans)
  * Roasted soy nuts
  * Soymilk, regular or low-fat, plain or flavored
  * Soy cheese, such as cheddar, mozzarella, cram cheese, or parmesan (includes all foods made with soy cheese)
  * Soy protein powders (e.g., performance or body-builder powders)
  * Soy yogurt, all types
  * Soy sauce, tamari, teriyaki sauce, Szechuan sauce, or hoisin sauce
  * Soy ice cream, tofutti, or other soy desserts
  * Tempeh, all types
  * Tofu, all types, including low-fat, flavored, marinated, and smoked
  * Tofu or soy breakfast sausage, bacon, or other breakfast meat
  * Tofu or soy cold cuts, hot dogs, or other deli meat substitutes
  * Veggie soy or tofu burger, ground meat substitute (texturized vegetable protein), or soy or tofu, chicken, or turkey
* Concurrent supplemental calcium and/or vitamin D and bisphosphonates allowed provided doses remain constant throughout the run-in and treatment portions of the trial