In 1982, the researchers published a study connecting a hepatitis B virus infection with increased risk for liver cancer.
And in 1985, they reported that people who eat foods rich with beta-carotene - found in many fruits and vegetables - are less likely to get lung cancer.
These and other early findings by the Japan-Hawaii Cancer Study have been repeatedly confirmed since, Dr. Abraham M.Y. Nomura, director, pointed out.
The study also was the first to connect a common bacteria that lives in the stomach, Helicobacter pylori, with stomach cancer, said Dr. Brian F. Issell, Cancer Research Center of Hawaii director.
He said the study has been "incredibly important" in terms of understanding characteristics associated with developing and surviving cancer.
Dr. Grant Stemmermann, former chief of pathology at Kuakini Medical Center, was the study's first principal investigator. Now at the University of Cincinnati Medical School, he's still a consultant to the project.
It began in 1971 as a collaborative effort with researchers in Japan's Akita Prefecture to look at how lifestyles affected cancer rates.
Japanese-American men were known to have lower rates of stomach cancer and higher rates of colon cancer than men in Japan.
The cancer study examined 8,006 Japanese-American men on Oahu born from 1900 to 1919. They had been identified in 1965 from Selective Service records for the Honolulu Heart Program.
Funded by the National Cancer Institute, the cancer study also recruited 2,500 brothers of the volunteers to expand its population base, Nomura said.
Money problems in 1980 ended the Japan component, he said. But the study still is going strong here, drawing on a bank of information and frozen serum samples from the volunteers to detect characteristics linked with cancer.
The program is observing its 25th anniversary with a record of more than 195 papers on its research.
Issell said the program has provided "unparalleled opportunities" to understand how lifestyle and environmental factors interact with inherited factors to cause cancer.
Being able to follow the Hawaii-Japanese men to their death and compare them with men in Japan "gives us a great handle" on different aspects of cancer, he said.
Nomura attributes the study's success to a "very good, very loyal staff." Key participants are Louise Suzuki, administrative assistant; Carol Miyahira, research coordinator, and Anne Tome, programmer analyst.
Drs. Jean Hankin, a nutritionist, Laurence Kolonel, epidemiologist, and James Lee, biostatistician, all at the Cancer Research Center, serve as consultants.
Nomura, an epidemiologist, also works at the Cancer Research Center and the University of Hawaii School of Public Health.
While the cancer findings are based on the Japanese-American men in the study group, he believes they're "pretty much applicable to other ethnic groups and women as well. The basic biology is there," he said.
The study found Hawaii-Japanese men consume more saturated fat and less salt, vegetable protein and complex carbohydrates than peers in Japan, Nomura said.
They are 1 to 2 inches taller and about 25 pounds heavier than men in Japan, he said.
About 21 percent, or 1,400 of the 6,860 study recruits, have been diagnosed with cancer in 25 years - less than 1 percent per year, he said.
Overall, the cancer rate for Hawaii Japanese men is a little lower than for those in Japan, Nomura said. However, he expects the rate to increase as the volunteers age.
Stomach and liver cancer rates are higher in Japan but colon, prostate and rectal cancer are higher here, and there's little difference in bladder and lung cancer rates, Nomura said.
The lower stomach and liver cancer rates among Hawaii-Japanese men, compared to those in Japan, "have contributed to their increased longevity in Hawaii," he said. About 3,690 of the original 8,006 volunteers are living. The youngest is 75.
Nomura noted that lung cancer rates in 1960-64 were 70 percent higher here than Japan.
Although the rates are comparable now, he expects more lung cancer in Japan in the future since Americans have become more health conscious.
The findings support guidelines recommended by the American Cancer Society to prevent cancer, Nomura said: "Stop smoking. Maintain a desirable weight. Include a variety of vegetables and fruits in the daily diet, and limit consumption of alcohol, if you drink at all."
The study is indebted to the Japanese-American men who contributed, he said, adding that the high rate of participation made it more valid. "It has been reproduced by others."
Highlights of the Japan-Hawaii Cancer Study:
Physical inactivity, high muscle mass or obesity, frequent alcohol consumption and cigarette smoking independently increase the risk for colon cancer.