Masahiko Sugano

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

PurposeThis 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.MethodsAretrospective review of patients with colorectal cancer surgically resected in single institutions in Hawaii and Japan from 1996 to 2002.ResultsA total of 410 Japanese-American patients (218 males; median age, 73 years) and621 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 wereclose 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).ConclusionsIn patients with colorectal cancer in Japanese-Americans in Hawaii, some of tumor characteristics have changed from those of native Japanese inJapan. 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 survivaloutcome of colorectal cancer may remain the same.

Methylenetetrahydrofolate reductase C677T is not associated with expression of pyrimidine metabolic enzyme genes in colorectal cancer

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism may influence the chemosensitivity of colorectal cancers to fluorouracil (5-FU) by increasing intracellular 5, 10-methylenetetrahydrofolate. The effect of this polymorphism on the expression of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyl transferase (OPRT) and thymidine phosphorylase (TP) in colorectal cancer was investigated. The MTHFR C677T polymorphism was analysed and TS, DPD, OPRT and TP mRNA expression was measured in tumour and adjacent normal mucosal tissue. In all patients, the genotypes of the tumour and normal tissues were identical. No differences were found in the expression of TS, DPD or TP mRNA by genotype in either tumour or normal tissue. Although the OPRT mRNA level in tumour tissue was not associated with the genotype, normal mucosa with the TT genotype showed a significantly higher OPRT mRNA level than mucosa with other genotypes. The MTHFR C667T polymorphism is not associated with intratumoural expression of TS, DPD, OPRT or TP.