YO5 - Solitary Cardiac Metastasis in BRAFV600E Mutation Colon Cancer

Case summary

Background

Cardiac metastases arise most commonly from melanomas and thoracic tumours, in the setting of multi-organ metastases. Here, we present a case of asymptomatic solitary metachronous cardiac metastasis from colon cancer.

Case Presentation

A 51-year-old Chinese lady with no known co-morbidities first presented with intestinal obstruction in 2021. She underwent extended right hemi-colectomy. Histopathology showed transverse colon adenocarcinoma (moderately differentiated, pMMR). Final pathologic stage classification (AJCC 8^th edition): pT4aN1aM0, Stage IIIB. She completed 8 cycles of adjuvant capecitabine and oxaliplatin chemotherapy. After a disease-free interval of 2 years, a surveillance computed tomography scan of thorax, abdomen and pelvis incidentally revealed a 6 cm hypodense mass in the right ventricle (RV). Serum carcinoembryonic antigen level was 62.0 ug/L. Transthoracic and transoeosphageal echocardiogram confirmed the presence of a large echogenic mass extending across the tricuspid valve, straddling the right atrium (RA) and RV, with only a small passage of blood into RV. She underwent excision of RA mass en bloc, tricuspid valve replacement and wide reconstruction of RA and superior vena cava. Histopathology confirmed a 6.5 x 6.5 x 6.0 cm adenocarcinoma, arising from the endocardium, consistent with metastases from a colonic primary. The initial primary colon tumour genotype was reviewed: BRAFV600E positive/extended RAS wild-type. Next-generation sequencing (NGS) with Foundation One platform was requested on the cardiac tumour. Systemic treatment will be planned following post-operative recovery.

Conclusion

Cardiac metastases from colorectal cancer are exceedingly rare; BRAFV600E mutations are reported in 7-10% of metastatic colorectal cancer and confer an aggressive disease phenotype. To our knowledge, this is the first report of BRAFV600E mutation colon cancer with solitary cardiac metastasis in literature. Urgent cardiac surgery for debulking and valve repair was indicated to prevent catastrophic cardiopulmonary failure. Close follow-up of clinical outcome after delivery of systemic therapy based on NGS will inform future management of this rare but important clinical entity.

Clinical trial identification

Editorial acknowledgement