Case report of multiple primary cancers and results of genetic testing to preliminarily explore their pathogenesis.

The occurrence of multiple primary malignancies in a single patient has been relatively rare. We report here the case of a 71-year-old man with three primary tumors of lung cancer, intrahepatic cholangiocarcinoma, and prostate cancer, and a preliminary study of the mechanisms by which multiple primary tumors develop at the genetic level. Because of the late stage of the patient's condition, large tumor burden, and poor physical status, the patient survived only a few months. In the case presented herein, cholangiocarcinoma, lung cancer, and prostate cancer were found simultaneously, and the pathogenic sites are not related. Whole-exome sequencing was performed on the pathological tissues to explore the mechanism that may underlie multiple primary cancers at the genetic level. Several gene mutations were found in this case. They involved cell proliferation, cell cycle regulation, genetic stability, metabolism, cell invasion, angiogenesis, cell apoptosis, and other pathways. It can be preliminarily inferred that the mechanism underlying multiple primary tumors is related to the abnormality of tumor-promoting and suppressing pathways.