International comparison on ras gene mutations in latent prostate carcinoma.

Latent carcinomas of the prostate, discovered at autopsy in men with no prior treatment for prostatic disease, were studied for ras proto-oncogene mutations. Subjects included 21 Japanese, 15 U.S. whites, 15 U.S. blacks, 20 Hawaiian Japanese and 10 Colombians. PCR and sequence-specific oligonucleotide hybridization identified mutations in 5 Japanese, in 1 Hawaiian Japanese, in 1 U.S. black, in 1 U.S. white and in 3 Colombians. The 5 Japanese tumor samples contained 3 point mutations in codon 12 of K-ras and 2 mutations in codon 12 of N-ras respectively. One tumor in a Hawaiian Japanese man also showed a K-ras point mutation at codon 12. Two Colombians and one U.S. black man had tumors with mutations at codon 61 of H-ras, while 1 Colombian showed an N-ras mutation at this codon. The overall frequency of ras gene mutations was low, but point mutations in codon 12 were most common in latent tumors of Japanese, who experienced the lowest incidence and mortality from this tumor. Latent tumors in men from ethnic groups with high mortality and incidence rates showed fewer ras mutations than the Japanese, and these were more likely to involve codon 61. This finding is consistent with prior studies of more aggressive clinical cancers in Japanese men that indicated a higher frequency of mutations at codon 61.

Cancer of the urinary bladder in the Pacific Basin.

The incidence of urinary bladder cancer differs markedly among the different ethnic and national groups in the Pacific Basin. Because of these differences, the following colaborative studies can be done to identify and characterize factors associated with bladder cancer: 1) study population groups with different levels of bladder cancer risk who reside in the same geographic setting; 2) study ethnically similar groups who differ in risk and reside in different locations; and 3) study population groups who differ in risks and reside in different geographical regions. Factors possibly related to bladder cancer that have been identified and studied by others include occupational exposure to certain chemicals, cigarette smoking, coffee drinking, artificial sweeteners, certain viruses, radiation exposure, phenacetin, bracken fern, Schistosoma haematobium, tryptophan metabolites, nitrosamines, estrogens, hair dyes, vitamin A, and ascorbic acid. In collaborative studies, the pathologic interpretation of histologic material and the content of the questionnaire should be well standardized, and the laboratory tests should be done at one laboratory. Among the population groups in the Pacific Basin, the Japanese in Hawaii and in Japan provide a unique resource for further investigation with respect to bladder cancer.