Ribociclib therapy in peritoneal carcinomatosis secondary to HER2-negative metastatic breast cancer: A clinical case with a positive outcome.

Although metastatic breast cancer can be fatal, a series of randomized double-blind placebo-controlled phase 3 trials (MONALEESA studies) have shown that ribociclib is an effective anticancer drug for the treatment of advanced breast cancer with bones, liver, lungs, and brain as major metastatic sites. Here, we report the clinical case of a woman with peritoneal carcinomatosis secondary to HER2-negative estrogen receptor-positive breast cancer successfully treated with ribociclib and letrozole. After 9-month follow-up, total body computed tomography imaging showed resolution of hypodense areas surrounding the hepatic hilus with concomitant reduction in both bile duct dilatation and peritoneal effusion, and abdominal lymphadenopathy was excluded. Notably, therapy was well tolerated throughout the treatment with no side effects.