Uterine carcinosarcoma/malignant mixed Müllerian tumor incidence is increased in women with breast cancer, but independent of hormone therapy

Mutational landscape implicates epithelial-mesenchymal transition gene TGF-β2 mutations for uterine carcinosarcoma after adjuvant tamoxifen therapy for breast carcinoma

Uterine carcinosarcoma (UCS) is a rare aggressive malignancy. Several reports previously described UCS occurring after tamoxifen therapy for breast carcinoma. However, the genetic landscape of tamoxifen-related UCS remains unclear. We performed whole-exome sequencing of two UCSs after tamoxifen therapy for breast carcinoma to determine mutational profile of UCSs and those corresponding breast carcinomas. Our results demonstrated that 374 somatic variants in 141 genes were shared across the two UCSs, whereas no shared somatic variations across the breast carcinomas were found. Pathway analysis indicated the MAPK pathway, including the epithelial-mesenchymal transition (EMT) inducer gene TGF-β2 mutations (c. 1039G > A and c. 1040C > T, both p.A347T), recurrently occurred in UCS, while ER-related gene EP300 (p.P16L) and ESR1 (p.V355I) mutations were identified independently in breast carcinomas. These findings highlight the EMT-related gene TGF-β2 variants in the tumorigenesis of tamoxifen-related UCS, support the possibility that tamoxifen mediates its effect on UCS by enhancing mutations of driver genes, and also provides the rationale for clinical investigation in ER-related gene mutation in breast carcinoma to predict the risk for UCS after tamoxifen treatment.

Uterine Malignant Mixed Müllerian Tumors Following Treatment with Selective Estrogen Receptor Modulators in Patients with Breast Cancer: A Report of 13 Cases and Their Clinicopathologic Characteristics

BACKGROUND

Breast cancer treatment with selective estrogen receptor modulators (SERMs) increasesthe incidence of uterine malignant mixed Müllerian tumors (uMMMTs). We examine clinicopathologiccharacteristics and prognosis of SERM-associated uMMMTs (S-uMMMTs) and discusspossible pathogenetic mechanisms.

METHODS

Among 28,104 patients with breast cancer, clinicopathologicfeatures and incidence of uMMMT were compared between patients who underwentSERM treatment and those who did not. Of 92 uMMMT cases that occurred during the same period,incidence, dose, and duration of SERM treatment, as well as overall survival rate, were comparedfor patients with breast cancer who underwent SERM treatment and those who did not (S-uMMMTvs NS-uMMMT) and for patients without breast cancer (de novo-uMMMT). Histopathologicalfindings and immunophenotypes for myogenin, desmin, p53, WT-1, estrogen receptor (ER) α, ERβ,progesterone receptor, and GATA-3 were compared between S-uMMMT and de novo-uMMMT.

RESULTS

The incidence of S-uMMMT was significantly higher than that of NS-uMMMT (6.35-fold).All patients with SERM were postmenopausal and received daily 20-40 mg SERM. CumulativeSERM dose ranged from 21.9 to 73.0 g (mean, 46.0) over 39-192 months (mean, 107). Clinicopathologicfeatures, such as International Federation of Gynecology and Obstetrics stage andoverall survival, were not significantly different between patients with S-uMMMT and NS-uMMMTor between patients with S-uMMMT and de novo-uMMMT. All 11 S-uMMMT cases available forimmunostaining exhibited strong overexpression/null expression of p53 protein and significantlyincreased ERβ expression in carcinomatous and sarcomatous components.

CONCLUSIONS

SERMtherapy seemingly increases risk of S-uMMMT development; however, clinicopathologic featureswere similar in all uMMMTs from different backgrounds. p53 mutation and increased ERβ expressionmight be involved in the etiology of S-uMMMT.