Rapid increase in colorectal cancer rates in urban Shanghai, 1972-97, in relation to dietary changes.

Abstract

Background: In urban Shanghai, the largest industrial and commercial city in China, the age-adjusted (to world standard) incidence rates for colorectal cancer increased from 14.8 to 24.1 per 10(5) man-years and from 11.7 to 20.7 per 10(5) woman-years between 1972-73 and 1996-97. These changes were even more pronounced for colon cancer. The reasons for the rapid increases in cancer rates are not fully understood, but may involve dietary habits that have changed substantially overthe past two decades.

Methods: Based on incidence data on 37000 colorectal cancers from 1972-1997 and dietary information during the past 20 years, an ecologic correlation analysis was performed.

Results: Available data indicate that per capita food consumption in Shanghai of vegetable oil, poultry, eggs, and pork rose rapidly during the period 1978-97, whereas consumption of seafood, grain, and fresh vegetables changed little or showed little consistent trends. Statistically significant positive associations were observed between colon cancer rates and per capita consumption of vegetable oil, poultry, fresh eggs and pork.

Discussion: These findings suggest that increases in dietary fat and certain protein consumption may play a role in the rising colon cancer rates in Shanghai.