AIM:To determine the prevalence and characteristics of additional primary malignancies in gastric cancer(GC)patients.METHODS:GC patients(862 total;570 men,292women;mean age 59.8±12.8 years)diagnosed at the Department of Gastroenterology at Pomeranian Medical University over a period of 23 years were included in this retrospective analysis of a prospectively maintained database.Mean follow-up time was 31.3±38.6 mo(range 1-241 mo).The following clinicopathological features of patients with synchronous tumors were compared to those with metachronous tumors:age,sex,symptom duration,family history of cancer,tumor site,stage(early vs advanced),histology,and blood group.GC patients with and without a second tumor were compared in terms of the same clinicopathological features.RESULTS:Of 862 GC patients,58(6.7%)developed a total of 62 multiple primary tumors,of which 39(63%)were metachronous and 23(37%)synchronous.Four(6.9%)of the 58 multiple GC patients developed two or more neoplasms.The predominant tumor type of the secondary neoplasms was colorectal(n=17),followed by lung(n=9),breast(n=8),and prostate(n=7).Age was the only clinicopathological feature that differed between GC patients with synchronous vs metachronous malignancies;GC patients with synchronous neoplasms were older than those with metachronous neoplasms(68.0±10.3 years vs 59.9±11.1years,respectively,P=0.008).Comparisons between patients with and without a second primary cancer revealed that the only statistically significant differences were in age and blood group.The mean age of the patients with multiple GC was higher than that of those without a second primary tumor(63.4±11.4years vs 59.5±13.0 years,respectively,P=0.026).GC patients with a second primary tumor were more commonly blood group O than those without(56.2%vs 31.6%,respectively,P=0.002).CONCLUSION:GC patients may develop other primary cancers;appropriate preoperative and postoperative diagnostic modalities are thus required,particularly if patients are older and blood group O. AIM: To determine the prevalence and characteristics of additional primary malignancies in gastric cancer (GC) patients. METHODS: GC patients (862 total; 570 men, 292 women; mean age 59.8 ± 12.8 years) diagnosed at the Department of Gastroenterology at Pomeranian Medical University over a period of 23 years were included in this retrospective analysis of a prospectively maintained database .Mean follow-up time was 31.3 ± 38.6 mo (range 1-241 mo). The following clinicopathological features of patients with synchronous tumors were compared to those with metachronous tumors: age, sex, symptom duration, family history of cancer, tumor site, stage (early vs advanced), histology, and blood group. GC patients with and without a second tumor were compared in terms of the same clinicopathological features. : Of 862 GC patients, 58 (6.7%) developed a total of 62 multiple primary tumors, of which 39 (63%) were metachronous and 23 (37%) synchronous. Flow or more neoplasms.The p redominant tumor type of the secondary neoplasms was colorectal (n = 17) followed by lung (n = 9), breast (n = 8), and prostate (n = 7). Age was the only clinicopathological feature that differed between GC patients with synchronous vs metachronous malignancies; GC patients with synchronous neoplasms were older than those with metachronous neoplasms (68.0 ± 10.3 years vs 59.9 ± 11.1 years, respectively, P = 0.008) .Comparisons between patients with and without a second primary cancer revealed that the only statistically significant differences were in age and blood group. The mean age of the patients with multiple GC was higher than that of those without those second a tumor (63.4 ± 11.4years vs 59.5 ± 13.0 years, respectively, P = 0.026) .GC patients with a second primary tumor were more often blood group O than those without (56.2% vs 31.6%, respectively, P = 0.002) .CONCLUSION: GC patients may develop other primary cancers; appropriate preoperative and postoperative diagnostic modals are thus required f patients are older and blood group O.