In U.S. women aged 20–49 between 2001 and 2018, those with severe obesity (BMI ≥ 40) had a stronger statistical link to cancer rates than those with mild obesity, suggesting that higher body weight levels correspond more closely with increased cancer occurrence.

Between 2001 and 2018, the number of U.S. women aged 20–49 with obesity rose steadily each year, with the most severe form rising faster. During the same period, the rates of breast, colorectal, and uterine cancer also rose, and these increases were closely aligned in timing across the population.

People with obesity have a higher likelihood of developing several types of cancer, including endometrial, postmenopausal breast, colorectal, liver, and pancreatic cancers, and the risk increases with higher levels of body weight for endometrial and postmenopausal breast cancer.

Higher rates of obesity in the early 2000s were statistically linked to higher rates of colorectal and uterine cancer in the following decade, indicating that obesity may be associated with cancer development after a delay of several years.

People with obesity have a higher chance of developing colorectal cancer compared to those without obesity, with men showing a greater increase in risk than women.

People who have been overweight or obese for many years have a higher risk of developing colorectal cancer than those whose weight changed recently, with the highest risk linked to weight measured 8 to 12 years before diagnosis.