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Weight loss may be a warning sign of colorectal cancer
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SAN DIEGO — Male sex and advanced age are both risk factors for the development of early-onset colorectal cancer, according to results of a case-control study presented at Digestive Disease Week.
Additionally, weight loss of at least 5 kg may be a warning sign for early-onset colorectal cancer, according to the data.
Eric Low, MD, MPH, of the University of California San Diego, said that incidence and mortality are rising in the United States among people younger than 50 years, but there have not been many clues as to why that is happening.
“Despite well-established risk factors for colorectal cancer overall, it’s not well understood what’s driving this rise among our young adult population,” Low said in his presentation. “This is in large part due to the fact that risk factors associated with early-onset colorectal cancer have not been widely studied.”
Researchers conducted the study to identify potential risk factors for early-onset CRC using a national sample of veterans aged 18 to 49 years who underwent colonoscopy between 1999 and 2014. They compared 651 patients with CRC with 67,416 controls who were CRC free at baseline and through 3 years of follow-up.
Compared with control individuals, patients with CRC were more likely to be older, male, current smokers, non-aspirin users and have a lower BMI (all P < .05).
After adjusting for several factors, researchers found that increasing age (OR = 1.05; 95% CI, 1.03–1.07) and male sex (OR = 2.21; 95% CI, 1.68–2.91) were linked with increased risk for early-onset CRC. Low said these findings were consistent with current CRC literature. Aspirin use and overweight or obesity were associated with a decreased risk for early-onset CRC.
In a post-hoc analysis, Low and colleagues identified a potential early clinical finding that weight loss could be associated with early-onset CRC. Patients with CRC had a negative average 10-year change in weight while controls had a positive average change (P < .0001). Researchers determined that 17.5% of patients with CRC lost at least 5 kg in the 5 years prior to baseline colonoscopy compared with 8.7% of the controls (OR = 2.23; 95% CI, 1.76–2.83).
“We believe that more intense efforts are required to identify potential causal factors and clinical signs that should trigger work-up for early-onset colorectal cancer,” Low said. “Hopefully, elucidating these risk factors may serve to clarify which individuals under age 50 may benefit from screening and lead to early detection and prevention of colorectal cancer.” – by Alex Young
Reference:
Low E, et al. Abstract 982. Presented at: Digestive Disease Week; May 18-21, 2019; San Diego.
Disclosures: Low reports no relevant financial disclosures. Please see the meeting disclosure index for all other authors’ relevant financial disclosures.
Perspective
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Violeta Popov, MD, PhD, FACG
Colorectal cancer (CRC) is the fourth most common cancer diagnosed among adults and the second leading cause of death from cancer. CRC incidence and mortality among older adults has been declining for several decades due to increased uptake of screening.
However, there has been a 51% increase in CRC incidence among adults younger than 50 years since 1994, and an 11% increase in mortality. In 2018, the American Cancer Society recommended that CRC screening start at age 45, rather than age 50. This significant increase in young-onset CRC is thought to correlate, among others, with increase in the prevalence of obesity and diabetes, well-described risk factors for CRC. Each 5-unit increment in BMI has been noted to be associated with an estimated 13% to 18% increase in CRC risk. Diabetes is also known to be associated with a 38% (95% CI, 1.26-1.51) increase in colon cancer risk and a 20% increase in rectal cancer risk (95% CI, 1.09-1.31).
Thus, the findings of this study from Low and colleagues come as a surprise. In a case-control study of 68,067 U.S. veterans who underwent colonoscopy under age 50 in the years 1999 to 2014, the index CRC cases (n = 651 cases) were compared with controls (n = 67,461) who were cancer-free for at least 3 years after the colonoscopy. Being overweight or obese was associated with a decreased risk for CRC. In fact, weight loss over the preceding 5 years prior to cancer diagnosis was correlated to diagnosis of CRC, with 17.5% of early-onset CRC cases losing more than 5 kg compared with 8.7% of controls (OR = 2.23; 95% CI, 1.76-2.83).
Other independent risk factors included age, smoking, male sex and nonuse of aspirin. The authors point out that weight loss preceded the diagnosis of young-onset CRC.
While this may seem contrary to previous studies showing a correlation between young-onset CRC and overweight and obesity, this study examines a population that already has developed CRC and, in some cases, advanced disease (data not available).
In fact, prior research has shown that young-onset CRC is more likely to present at an advanced stage than patients with older-onset CRC. Thus, the research by Low and colleagues is consistent with published data. It would be helpful to know if there was association between being underweight/losing weight in the preceding years and advanced cancer stage in this study, and hopefully the authors will present the data in the final paper.
A take-away point from this study of a large national sample of veterans is that significant weight loss should trigger a thorough evaluation even in younger patients. It does not refute the notion that obesity, overweight and even Western-style diet as noted in another presentation at DDW, are risk factors for CRC.
References:
- Ahnen DJ, et al. The increasing incidence of young-onset colorectal cancer: a call to action. Mayo Clin Proc. 2014;89(2):216-24.
- Edwards BK, et al. Annual report to the nation on the status of cancer, 1975-2006, featuring colorectal cancer trends and impact of interventions (risk factors, screening, and treatment) to reduce future rates. Cancer. 2010;116:544–573.
- Liu PH, et al. Association of Obesity with Risk of Early-Onset Colorectal Cancer Among Women. JAMA Oncol. 2019;5(1):37-44.
- Siegel R, et al. Cancer statistics, 2012. CA Cancer J Clin. 2012;62:10–29.
- Wolf AMD, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA Cancer J Clin. 2018;68(4):250-281.
- You YN, et al. Young-onset colorectal cancer: is it time to pay attention? Arch Intern Med. 2012;172:287–289.
- Yuhara H, et al. Is diabetes mellitus an independent risk factor for colon cancer and rectal cancer? Am J Gastroenterol. 2011;106:1911–1921.
- Zheng X, et al. Comprehensive Assessment of Diet Quality and Risk of Early-Onset Colorectal Adenoma. Gastroenterology. 2019;156(6):S-208.
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