Comparison of characteristics and survival of colorectal cancer between Japanese-Americans in Hawaii and native Japanese in Japan.

PURPOSE: This study was designed to investigate whether characteristics, prognostic risk factors, and survival of colorectal cancer of Japanese-Americans in Hawaii are different from those of native Japanese in Japan. METHODS: A retrospective review of patients with colorectal cancer surgically resected in single institutions in Hawaii and Japan from 1996 to 2002. RESULTS: A total of 410 Japanese-American patients (218 males; median age, 73 years) and 621 native Japanese patients (382 males; median age, 65 years) were included. There were significant differences in age (P < 0.001), age distribution (P < 0.001), gender (P = 0.008), preoperative carcinoembryonic antigen (P < 0.001), and anatomic site distribution (P < 0.001). The tumor characteristics of Japanese-American patients were close to the general American population compared with the Surveillance, Epidemiology, and End Results data. There were no differences in tumor size, histologic grade, each of T, N, M status and TNM stage between the two groups. The overall five-year survival rates (Japanese-Americans, 75.5 percent; native Japanese, 76.2 percent; P = 0.55) and survival rates in each of four stratified stages were similar. Risk factors associated with survival were not different, except for carcinoembryonic antigen (P = 0.036). CONCLUSIONS: In patients with colorectal cancer in Japanese-Americans in Hawaii, some of tumor characteristics have changed from those of native Japanese in Japan. However, there are no remarkable differences in prognostic factors and survival between the two groups. The present study suggests that certain changes of colorectal cancer characteristics that were seen in Japanese-American may occur in native Japanese in Japan in the near future, although the survival outcome of colorectal cancer may remain the same.

Enhancement of the anti-tumor activity of S-1 by low-dose cisplatin in mice bearing the sarcoma-180 model.

The combination of S-1, consisting of 1 mol/l tegafur, 0.4 mol/l 5-chloro-2,4-dihydroxypyridine and 1 mol/l potassium oxonate, plus low-dose cisplatin has showed promising anti-tumor activities in experimental and clinical studies. The aim of this study was to investigate the mechanism of this combination chemotherapy. Mice bearing sarcoma-180 cells were divided into groups of seven animals each - Group A: no treatment; Group B: 5-fluorouracil (5-FU) 10 mg/kg continuous i.p. infusion; Group C: S-1 10 mg/kg p.o.; Group D: cisplatin 0.2 mg/kg i.p.; Group E: B+D; Group F: C+D. Treatments were given for 5 consecutive days, and then anti-tumor activity, the concentration of 5-FU, the thymidylate synthase inhibition rate (TSIR) and the level of 5-FU incorporated into RNA (F-RNA) in tumor tissue were evaluated. Anti-tumor activity in Group F was higher than in any other group. A significantly higher concentration of 5-FU in tumor was detected in the S-1-treated groups (C and F) than in the 5-FU-treated groups (B and E). No differences in TSIR were observed between the groups treated with 5-FU or S-1 with or without cisplatin; however, the F-RNA level in Group F was about 1.24 times significantly higher than that in Group C. Group F showed the highest anti-tumor activity, with increasing intratumoral levels of 5-FU and F-RNA, but not that of TSIR. These results suggested that the superior anti-tumor activity obtained by S-1+cisplatin might be associated with an incorporation of 5-FU into RNA.