What is the new study about early-onset colorectal (cancer of the colon or rectum)?

From the Guidelines

The most recent and highest quality study recommends initiating colorectal cancer (CRC) screening at the age of 45 years for individuals at average risk, due to the increasing incidence of early-onset CRC in people under 50 years old. This is based on a microsimulation analysis that showed starting screening at 45 years resulted in the most optimal balance of burden to benefit of screening 1. The study also found that initiating screening colonoscopy at age 45 years instead of 50 years cost $33,900 per quality-adjusted life-year gained, and initiating FIT at 45 years instead of 50 years cost $7700 per quality-adjusted life-year gained.

Key Findings

• The incidence of CRC in people younger than 50 years has been increasing, with an estimated 10% of colon cancers and 25% of rectal cancers expected to be early-onset CRC over the next decade 1.
• A cohort study found that undergoing lower endoscopy was associated with a significantly lower risk of incident CRC when age at initiation was before age 45 years, 45–49 years, 50–54 years, and 55 years or older 1.
• The US Multi-Society Task Force on Colorectal Cancer, the US Preventive Services Task Force, and the American Cancer Society recommend initiating CRC screening in individuals at average risk for CRC at the age of 45 years, while acknowledging limited evidence 1.

Screening Strategies

• For individuals with a family history of CRC and/or adenomas, empirical evidence on when to initiate screening is limited, but a microsimulation analysis suggested screening people with 1 FDR affected with CRC every 3 years beginning at the age of 40 years was the most cost-effective 1.
• An analysis conducted according to the age at diagnosis of affected relatives suggested that CRC screening should begin at age 30 years for those with 1 affected FDR diagnosed before age 45 years and at age 20 years for those with 2 affected FDRs before the age of 50 years or 1 affected FDR and 1 second-degree relative diagnosed before the age of 50 years 1.

Recent Guidelines

• The NCCN Guidelines Insights focus on recent changes in the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for CRC Screening, including a summary of relevant updates 1.
• The guidelines highlight the importance of screening individuals for CRC to reduce mortality by detecting cancer at an early, curable stage and may decrease incidence by detecting and removing precancerous polyps 1.

From the Research

Overview of Early Onset Colorectal Cancer

• The incidence of early-onset colorectal cancer (CRC), which occurs in individuals <50 years of age, has been increasing worldwide, particularly in high-income countries 2.
• The reasons for this increase remain unknown, but plausible hypotheses include greater exposure to potential risk factors such as a Western-style diet, obesity, physical inactivity, and antibiotic use, especially during the early prenatal to adolescent periods of life 2, 3.

Clinical and Molecular Features

• Early-onset CRCs have differential clinical, pathological, and molecular features compared with later-onset CRCs 2, 4.
• Younger patients appear to have more distal or rectal disease, a more advanced stage of disease at presentation, and more unfavorable histological features 5.

Risk Factors and Molecular Underpinnings

• Only a small fraction of early-onset CRC cases is attributed to known hereditary mutations and fit the canonical pathway of late-onset colorectal cancer development 4.
• The synergetic effect of single-nucleotide polymorphisms and environmental factors on the early onset of CRC is an area of ongoing research 4.
• Potential risk factors for early-onset CRC include a Western-style diet, stress, antibiotics, synthetic food dyes, monosodium glutamate, titanium dioxide, and physical inactivity and/or sedentary behavior 3.

Trends and Demographics

• The incidence of early-onset CRC has increased overall from 2001 to 2016, but the trends were markedly different for whites, blacks, Asians/Pacific Islanders, and Hispanics 6.
• Whites were the only racial group with a consistent increase in incidence across all younger ages, with the steepest rise seen after 2012 6.
• Greater increase in early-onset CRC incidence was observed for males, left-sided tumors, and regional and distant disease 6.