title: Molecular genetic characterization of tamoxifen-associated endometrial cancer.
abstract: OBJECTIVE
  The non-steroidal, selective estrogen receptor modulator tamoxifen is currently the most extensively used hormonal agent for the prevention and treatment of estrogen receptor-positive breast cancer. Epidemiologic studies and clinical trials have shown an increased risk of endometrial cancer with tamoxifen exposure; however, few studies have examined these tumors on a molecular level. We sought to elucidate the molecular genetic alterations found in tamoxifen-associated endometrial cancer.
  
  
  METHODS
  Twenty-nine breast cancer patients with a history of tamoxifen use who subsequently developed endometrial cancer were retrospectively identified and matched for endometrial histologic subtype and grade to 29 endometrial cancers from breast cancer patients never exposed to tamoxifen. Endometrial tumor tissue was microdissected and genomic DNA extracted for each case. Direct DNA sequencing of the most commonly mutated genes in sporadic endometrial cancer, PTEN, K-RAS, TP53, and CTNNB1, was performed in addition to microsatellite instability (MI) studies. Fisher's Exact Test was utilized for statistical analyses.
  
  
  RESULTS
  Of 29 tamoxifen-associated cancers, 10 (34.5%) contained PTEN mutations compared to 13 (44.8%) of the non-tamoxifen-associated cancers (P = 0.59). All PTEN mutations were found in tumors with endometrioid histology, reflecting what is seen in sporadic endometrial cancers. Mutations of K-RAS, TP53, and microsatellite instability were present in similar frequencies between the two breast cancer groups, and moreover, these were similar to mutational frequencies found in sporadic endometrial cancer.
  
  
  CONCLUSIONS
  Tamoxifen and non-tamoxifen-associated endometrial carcinomas arising in women with breast cancer contain similar genetic alterations to those of sporadic endometrial carcinomas.
authors.affiliation: Division of Gynecologic Pathology, Department of Pathology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Prasad
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Wayne
authors.initials: W
authors.lastname: Douglas
authors.forename: Richard R
authors.initials: RR
authors.lastname: Barakat
authors.forename: Lora Hedrick
authors.initials: LH
authors.lastname: Ellenson
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy; D018269:Carcinoma, Endometrioid / Q000139:chemically induced / Q000235:genetics; D003043:Cocarcinogenesis; D003598:Cytoskeletal Proteins / Q000235:genetics; D016889:Endometrial Neoplasms / Q000139:chemically induced* / Q000235:genetics* / Q000473:pathology; D005260:Female; D016158:Genes, p53 / Q000235:genetics; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D018895:Microsatellite Repeats / Q000235:genetics; D009154:Mutation; D009367:Neoplasm Staging; D016609:Neoplasms, Second Primary / Q000139:chemically induced* / Q000235:genetics*; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D012189:Retrospective Studies; D020845:Selective Estrogen Receptor Modulators / Q000009:adverse effects* / Q000627:therapeutic use; D013629:Tamoxifen / Q000009:adverse effects* / Q000627:therapeutic use; D015534:Trans-Activators / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D020845:Selective Estrogen Receptor Modulators; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D051176:beta Catenin; D013629:Tamoxifen; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human