Multiple primary cancers with prostate malignant tumor as the initial diagnosis: a case report.

With the advancement of medical technology and improvements in living standards, the survival time of many cancer patients has been prolonged. However, a significant proportion of these patients develop multiple primary cancers (MPC), which indicates a poorer prognosis. Currently, there are no specific guidelines for managing MPC. This article reports a rare case of an elderly male patient who, during a six-year follow-up period, was diagnosed with four primary tumors in different organs including prostate cancer (first manifestation), renal cancer, bladder cancer, and lung cancer. Genetic testing of tumor tissues revealed an EGFR mutation in the lung cancer tissue and BAP1 gene deletion in the renal cancer tissue. Over the six-year follow-up, the patient underwent radical prostatectomy, partial nephrectomy, transurethral resection of bladder tumor, and radical left lung resection, with good postoperative recovery. This case represents MPC involving three urogenital system tumors and highlights the rare coexistence of EGFR mutation and BAP1 gene deletion across different organ-specific cancers. It underscores the necessity of genetic testing for MPC patients and demonstrates that aggressive management of primary tumors can improve the patient's quality of life. This case provides valuable insights for clinical research and treatment strategies for MPC.