Intrauterine Levonorgestrel and Observation or Observation Alone in Preventing Atypical Endometrial Hyperplasia and Endometrial Cancer in Women With Hereditary Non-Polyposis Colorectal Cancer or Lynch Syndrome

DISEASE CHARACTERISTICS:

* Proven to carry a pathogenic germline mutation in a DNA mismatch repair gene causing Lynch syndrome (hereditary non-polyposis colorectal cancer) (usually MSH2, MLH1, or MSH6)
* Meets both of the following criteria:

  * Has a family history of Lynch syndrome according to the following Amsterdam or modified Amsterdam criteria:

    * Three relatives with a Lynch syndrome-related cancer (colorectal, small bowel, endometrial, ovarian, urothelial, or hepatobiliary)
    * One is a first-degree relative of the other two
    * Two generations affected
    * One relative diagnosed before age of 50
  * Personal history of colorectal cancer (i.e., a large, villous, or severely dysplastic colorectal adenoma) before the age of 40 OR history of small bowel, hepatobiliary, or urothelial cancer AND has an affected family member with an abnormal tumor immunohistochemistry staining for Lynch syndrome
* No active genital malignancy, breast carcinoma, or other estrogen dependent tumor

  * History of genital malignancy, breast carcinoma, or other estrogen dependent tumor allowed at the discretion of the investigator

PATIENT CHARACTERISTICS:

* Must have an intact uterus and not planning to undergo a prophylactic hysterectomy
* Not pregnant
* Not planning to become pregnant within the next 3 years
* No abortion resulting in infection within the past 3 months
* No pelvic inflammatory disease (PID) within the past 6 months or recurrent PID
* No clinically significant submucous myomas requiring treatment

  * Small subserous or intramural myomas, clinically assessed as insignificant allowed
* No known hypersensitivity to the constituents of the Mirena® IUS
* No unresolved abnormal cervical smear and/or current cervical dysplasia
* No trophoblastic disease with elevated hCG levels
* No liver tumor or other acute or severe liver disease
* No clinically significant condition or laboratory result that might, in the opinion of the investigator, compromise patient safety, interfere with evaluations, or prevent completion of the study
* No other active malignancy
* No history of stroke or myocardial infarction
* No history of bacterial endocarditis or severe pelvic infection after any prosthetic valve replacement or in patients with an anatomical lesion of the heart

PRIOR CONCURRENT THERAPY:

* No other concurrent use of intrauterine devices
* No concurrent therapy for cancer