An In-Depth Look at Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT): Clinical Implications from Recent Molecular Findings

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a highly aggressive cancer in young women. The histogenesis remains unclear although a potential origin of germ cells has been suggested recently. The high throughput next generation sequencing techniques have facilitated the identification of inactivating SMARCA4 mutations as the driver of SCCOHT. These findings may greatly impact on the prevention, diagnosis, molecular classification and treatment of SCCOHTs. The SMARCA4 mutations, typically associated with dual loss of BRG1 and BRM expression, are highly sensitive and specific for the diagnosis of SCCOHT. Germline mutations of SMARCA4 support familial SCCOHT with a critical requirement of genetic counseling and possible prophylactic surgery for carriers. SCCOHT, malignant atypical teratoid/rhabdoid tumors, thoracic sarcomas and some undifferentiated carcinomas harbor rhabdoid morphology and mutations in the SMARC genes, generating an emerging molecular classification of SMARC-mutated tumors. A multi-modality treatment approach consisting of surgery and high dose multi-agent chemotherapy in atypical teratoid/rhabdoid tumors may have potential benefits for SCCOHT patients. Preliminary studies have implicated that the inhibitors targeting EZH2 and the receptor tyrosine kinase, and anti-PD-L1 immunotherapy might be potentially effective for SCCOHT patients. These recent advances on molecular genetics, diagnosis and treatment of SCCOHT address the necessity of multiple institutional collaboration work among oncologist, pathologist, genomic scientist, geneticist, molecular biologist, and pharmacologist.