Sex differences in the association of obesity and colorectal cancer risk.

Epidemiological research has convincingly shown that obesity increases colorectal cancer (CRC) risk, with generally stronger associations observed in men than in women. Evidence from the past several years has demonstrated a divergent pattern between men and women regarding the weight changes throughout life or timing of obesity for CRC risk. For men, weight gain later in life appears to be an important risk factor for CRC that mostly accounts for their generally strong association between adult body mass index and CRC risk. For women, however, early life obesity seems to be more important than adult weight gain in determining CRC risk. A knowledge of these sex patterns may have implications on better understanding colorectal carcinogenesis and may further improve prevention efforts for CRC.