Obesity Raises Early Colon Cancer Risk in Women

Young women with obesity likely have an increased risk of developing early-onset colorectal cancer (CRC), according to new research.¹

This finding could have important implications going forward as researchers continue working to uncover the etiopathogenesis of early-onset CRC, said lead study author Po-Hong Liu, MD, MPH, of the University of Texas Southwestern Medical Center, in an email to Consultant360.

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Dr Liu and colleagues arrived at their conclusion after performing one of the first studies to prospectively investigate the association between obesity and risk of CRC diagnosed in patients younger than age 50 years.

The study incorporated data from 85,256 women from the ongoing Nurses’ Health Study II. Specifically, the researchers analyzed participants’ current body mass index (BMI), BMI at age 18 years, and weight gain since age 18 years. They also calculated relative risk (RR) for early-onset CRC.

By the end of the study, 114 cases of early-onset CRC had been identified over 1,196,452 person-years of follow-up. The multivariable RRs were 1.37 and 1.93 for overweight and obese women, respectively, compared with women with a BMI of 18.5 kg/m² to 22.9 kg/m². The RR increased by 1.20 for each 5-unit increment in BMI.

The researchers noted similar associations in women without a family history of CRC and without lower endoscopy within the last decade, with BMI at age 18 years and weight gain since age 18 years as contributors.

“Our study was one of the first to point out that BMI at age 18 years and weight changes since that time may play important role in the etiology of early-onset CRC,” Dr Liu told Consultant360.

Additional RRs for early-onset CRC were:

• 1.32 for women with a BMI of 21.0 kg/m² to 22.9 kg/m² and 1.63 for women with a BMI of 23.0 kg/m² or greater at age 18 years (compared with a BMI of 18.5 to 20.9 kg/m²).
• 1.65 for women who gained 20.0 kg to 39.9 kg [approximately 44 lbs to 88 lbs] and 2.15 for women who gained 40.0 kg [approximately 88 lbs] or more after age 18 years (compared with women who had gained less than 5 kg [approximately 11 lbs] or had lost weight).

“Further investigations among men and to elucidate the underlying biological mechanisms are warranted,” the researchers wrote.

The findings were recently published in JAMA Oncology.

Key Takeaways

As the rates of early-onset CRC incidence continue to rise significantly among individuals aged 20 to 49 years, these findings could have several implications in the future if they are validated, Dr Liu told Consultant360.

Both clinicians and patients should be more aware of the potentially increased risk of early-onset CRC among younger individuals who are overweight or obese, he said

In addition, clinicians should help ensure that these patients are compliant with updated screening guidelines from the American Cancer Society, which recommend that screening begins at age 45 years for those with average risk of CRC.²

—Christina Vogt

References:

1. Liu PH, Wu K, Ng K, et al. Association of obesity with risk of early-onset colorectal cancer among women [Published online October 11, 2018]. JAMA Oncol. doi:10.1001/jamaoncol.2018.4280

2. Wolf AMD, Fontham ETH, Church TR, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA. 2018;68(4). https://doi.org/10.3322/caac.21457