Cancer disparities between mainland and island Puerto Ricans.
Examination of cancer rates in a single Hispanic subgroup-Puerto Ricans- and comparison of incidence rates among mainland Puerto Ricans living in the United States, island Puerto Ricans in Puerto Rico, and U.S. non-Hispanic whites to reveal ethnic-specific cancer patterns and disparities in Puerto Ricans. Incidence data were obtained from the cancer registries of Puerto Rico and three U.S. northeastern states (New York, New Jersey, and Connecticut) with a high density of mainland Puerto Ricans. Age-adjusted rates were compared by standardized rate ratios (SRRs). Total cancer incidence was the lowest in island Puerto Ricans, intermediate for mainland Puerto Ricans, and highest in U.S. non-Hispanic whites. Compared to mainland Puerto Ricans, islanders had significantly lower rates (p<0.05) for major cancers-lung (SRRs=0.36 in males and 0.29 in females), prostate (SRR=0.71), female breast (SRR=0.73), and colon-rectum (SRRs=0.74 in males and 0.65 in females)-as well as several less common cancers (urinary bladder; non-Hodgkin lymphoma; liver; kidney and renal pelvis; pancreas; thyroid; leukemia; and skin melanoma). Overall cancer rates in mainland Puerto Ricans were modestly lower than those in U.S. non-Hispanic whites, but mainland Puerto Ricans had the highest rates for stomach, liver, and cervical cancers among the three populations. Despite socioeconomic disadvantages, island Puerto Ricans have relatively low cancer incidence. Identifying contributing factors would be informative for cancer research, and understanding the reasons for increased cancer risk in their mainland counterparts would facilitate the development of ethnic-specific intervention programs.