Associated primary tumors in patients with gastric cancer.

Goal: To determine the prevalence of associated primary tumors in patients with gastric cancer.
Study: Retrospective study of 2,668 patients with gastric cancer observed at our department between July 1974 and December 1999. Associated tumors were diagnosed using Warren and Gates criteria, and included tumors that were not considered to be a metastasis, invasion, or recurrence of gastric cancer.
Results: Of all, 3.4% (n = 78) had primary tumors other than gastric cancer, 27% of which were synchronous (n = 21) and 73%, metachronous (n = 57). The mean follow-up time was 4 years (range, 1-13 years), and the male-to-female ratio was 1:1. The median age at diagnosis of gastric cancer was 67 years (range, 37-84 years), 69 years for patients with synchronous tumors versus 60 years for those with metachronous (p = 0.050). For at least half the patients the median time interval to metachronous cancer was 3 years (range, 1-22 years). Seventy-eight percent (n = 61) had two cancers; most were colonic (19%), uterine and ovarian (16%), and breast tumors (13%). Seventeen percent (n = 13) had three tumors: colon (46%), breast (23%), and skin (23%). Four percent (n = 3) had four tumors. One case with seven tumors was also observed [colon, breast (two tumors), uterus, skin, and stomach (two tumors)]. No statistically significant differences were found between synchronous and metachronous with regard to sex, gastric cancer location, and staging (TNM). Sixty-three percent (n = 49) died while under observation.
Conclusions: We found associated tumors in 3.4% of patients with gastric cancer. The most frequent associated tumors were breast and colon cancer. Surveillance for these tumors would be appropriate, at least in first years, after diagnosis of gastric cancer.