Researchers in Japan have found that cigarette smoking may increase the risk of colorectal cancer (CRC) incidence in a Japanese population. This is the first such study in a Japanese population; a correlation between cigarette smoking and CRC risk has already been identified in the Western population.

CRC incidence has seen a rapid rise in the Asian population, although 60% of CRC cases occur among developed nations. Specifically, Japan experienced an increase in cases from 1978 to 1993 and has remained stable since then but is still among the top 10 countries with the highest incidence of CRC. Another Japanese study found a gender-based difference in CRC incidence, with men being more susceptible to rectal cancer and women being more susceptible to colon cancer.

Environmental and lifestyle factors, such as smoking, can increase the risk of CRC. In Japan, for instance, 80% of men and 20% of women were smokers in the 1950s. However, a significant reduction was observed in smoking rates by 2017: only 32% of men and 9% of women were smokers. The age-standardized CRC incidence rate was 22.2 in 1978 and 38.9 in 2018.

The current study found that men who were ever, current or former smokers had a statistically significant higher risk of CRC than never smokers. Women who were ever, current or former smokers did not have an increased risk of CRC, but a significantly greater risk of distal colon cancer.

You can read the full article on the Colon Cancer Foundation’s website.