Tamoxifen-associated malignant endometrial tumors: pathologic features and expression of hormone receptors estrogen-alpha, estrogen-beta and progesterone; a case controlled study

Gynecol Oncol. 2004 Feb;92(2):553-8. doi: 10.1016/j.ygyno.2003.10.040.


Objective: Expression analysis of estrogen receptor-beta (ER-beta) and estrogen receptor-alpha (ER-alpha) in tamoxifen-associated malignant endometrial tumors (TAMET) has not previously been published. Antiestrogens complexed with ER-beta have been reported to result in activation of the activator protein-1 (AP-1) pathway that may result in cell proliferation and tumor growth. In this study, the pathologic features and expression of ER-alpha, ER-beta and progesterone receptor (PR) in TAMET were determined and compared to matched cases of non-tamoxifen-associated endometrial cancers.

Methods: TAMET (n = 33) were evaluated for pathologic features (tumor type, grade, depth of myometrial invasion, lymphvascular space invasion and lymph node status), expression of ER-alpha, ER-beta and PR, and survival data (mean follow-up: 28.7 months). Each case was matched to two control patients with spontaneous endometrial cancers according to tumor type, grade and stage as well as patient age and weight (mean follow-up: 51.5 months). Formalin-fixed paraffin-embedded tissue sections were immunostained with anti-ER-alpha (1D5, Dako, Carpinteria, CA) and anti-PR (PgR636, Dako). Expression scores were determined as a sum of the product of staining intensity and proportion of cells staining (H-score). Deparaffinized sections of tumor were microdissected followed by RNA isolation. Quantification of ER-beta mRNA was performed by real-time quantitative RT-PCR with results expressed as a percentage of beta-actin mRNA.

Results: Of the 33 cases 20 were endometrioid (8 grade 1, 10 grade 2, 2 grade 3), 9 papillary serous and 4 malignant mullerian mixed tumors. Using a multivariate conditional regression model, TAMET had lower ER-alpha expression (P = 0.018), higher PR expression (P = 0.029), and more frequent expression of ER-beta (P = 0.032) as compared to control cases. Cases with TAMET had more deaths from cancer and significantly worse survival from disease than controls (P = 0.01 by a log rank test).

Conclusion: TAMET are characterized by a lower expression of ER-alpha, higher expression of PR and more frequent expression of ER-beta as compared to spontaneous tumors. Differential expression of ER-alpha and ER-beta may alter the expression of key target genes (such as those induced by AP-1-dependent gene transcription), and contribute to the pathogenesis and clinical behavior of these tumors. Survival from disease was significantly worse for cases with TAMET as compared to controls.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Hormonal / adverse effects*
  • Case-Control Studies
  • Endometrial Neoplasms / chemically induced
  • Endometrial Neoplasms / metabolism*
  • Endometrial Neoplasms / pathology*
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Female
  • Humans
  • Middle Aged
  • Receptors, Estrogen / biosynthesis*
  • Receptors, Progesterone / biosynthesis*
  • Tamoxifen / adverse effects*


  • Antineoplastic Agents, Hormonal
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Tamoxifen