Multiethnic/Minority Cohort Study of Diet and Cancer

Laurence Kolonel, M.D., Ph.D.
University of Hawaii-Manoa
Cancer Research Center of Hawaii
Honolulu, Hawaii
Funded since 1993

The Multiethnic/Minority Cohort Study was established in Hawaii and Los Angeles in 1993-1996 to explore the relationship of diet and other lifestyle factors to cancer. The cohort is comprised of more than 215,000 men and women primarily of African-American, Japanese, Latino, Native Hawaiian, and Caucasian origin, and is unique among existing cohort studies in its ethnic diversity and representation of minority populations.

At entry to the cohort study, each participant completed a 26-page mail questionnaire that included an extensive quantitative diet history, as well as other demographic, medical, and lifestyle information. Multiple 24-hour diet recalls were collected on more than 2,000 of the participants in a calibration study designed to permit correction of nutrient intake estimates for measurement error.

During the grant period 1998-2003, a brief follow-up questionnaire to update selected dietary and non-dietary baseline information was completed by more than 80% of the participants; in the current period of 2003-2008, the baseline dietary questionnaire will be repeated. Out-migration rates after seven years were low (< 5 percent), supporting the use of computer linkage with the population-based cancer registries in Hawaii and California to identify incident cases. More than 25,000 cases of breast, prostate, colorectal, and lung cancer are expected by 2007.

Initial dietary analyses, based on an average four years of follow-up, are underway. Preliminary findings include positive associations of alcohol with breast cancer, dairy products with prostate cancer, and saturated fat with lung cancer, and inverse associations of legumes with breast cancer, carotenoids and certain vegetables with lung cancer, and dietary fiber and folate with colorectal cancer.

The much larger number of cases by the end of the current follow-up period will enable the investigators to further examine these dietary relationships by ethnicity and stage of disease, to study other cancer sites (pancreas, bladder, ovary, endometrium), and to examine gene-diet interactions.

Other aims for this period include study of the:

• relationship of flavonoids and heterocyclic amines to colorectal, lung, bladder, and other cancers;
• use of exogenous hormones and cancers of the breast, ovary, and colorectum; and
• use of nonsteroidal anti-inflammatory drugs and cancers of the colorectum, lung, breast, and ovary.

In addition, biochemical measurements on 750 members of the cohort will be used to develop new dietary exposure variables that can improve testing of etiologic hypotheses.

Findings from the Multiethnic/Minority Cohort Study should help not only to identify dietary and other risk factors for cancer, but also to better understand the basis for ethnic variations in cancer incidence.