Multiple primary cancers in patients with gastric cancer.

BACKGROUND/AIMS: Some gastric cancer patients have multiple primary cancers (MPC). We evaluate the current status of MPC with gastric cancer. METHODOLOGY: 2,109 gastric cancer patients treated between 1987 and 2002 were analyzed. RESULTS: There were 99 MPC with gastric cancer (4.7%). Second cancer (77.8%) was discovered within 5 years before and after the onset of gastric cancer. 34.3% of patients were discovered within 1 year (synchronous tumor). In the 77 male patients, prostate cancer was the most common occurrence (19.5%), followed by cancers of the colon (18.2%) and liver (14.3%). In the 22 female patients, colon cancer was the most common (31.9%) followed by breast and cervix cancers (22.7%). These cancers were the most common diseases in Taiwan in the same period. Gastric cancer patients with MPC had less stromal reaction and better survival than those without. Patients with metachronous secondary tumors had more peritoneal dissemination and worse survival than those with synchronous primary cancer. CONCLUSIONS: Gastric cancer patients may develop second cancer(s), which is often a current prevalent malignancy. Knowledge of time to development and mode of organ association may allow clinicians to detect potentially curable subsequent cancer(s).