Early-onset colorectal cancer has distinct clinical and genetic features

By Reuters Staff

NEW YORK (Reuters Health) - 13/3/2019

Colorectal cancer that is diagnosed before age 50 has clinical and genetic features that differ from those seen in colorectal cancer diagnosed later in life, according to new research.

"We need to appreciate that there are unique biologic subtypes within young patients that may affect how their cancers behave and may require a personalized approach to treatment," Dr. Jonathan Loree of The University of Texas MD Anderson Cancer Center in Houston said in a news release. The findings were published online March 11 in Cancer.

While the incidence of CRC has fallen in patients aged 50 years and older, likely due to screening, the incidence of early-onset CRC has been increasing over the past two decades.

Dr. Loree and colleagues analyzed differences between early-onset and late-onset CRC in more than 36,000 patients across four cohorts. They divided patients into six age groups - 18 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69, and 70 and older - and compared their characteristics.

Among the key observations:

  • Early-onset patients (<50 years) were significantly more apt to have microsatellite instability, synchronous metastatic disease, primary tumors in the distal colon or rectum, and fewer BRAF V600 mutations in comparison with patients with onset at age 50 or older.

  • Patients with onset between age 18 and 29 had fewer adenomatous polyposis coli (APC) mutations (odds ratio, 0.56; P=0.015) and an increased prevalence of signet-ring histology (OR, 4.89; P<0.0001) relative to other patients younger than 50 years.

  • In patients younger than 40, consensus molecular subtype 1 (CMS1) was the most common subtype, whereas CMS3 and CMS4 were uncommon (P=0.003). CMS2 was relatively stable across age groups.

  • Early-onset patients with inflammatory bowel disease (IBD) were more likely to have mucinous or signet-ring histology (OR, 5.54; P=0.0004) and less likely to have APC mutations (OR, 0.24; P=0.019) compared with early-onset patients without predisposing conditions.

These findings, from one of the largest cohorts of early-onset CRC, show that it has distinct clinical and molecular features, "and it may be more appropriate to consider age as a continuum when one is evaluating CRC," the researchers write in their article.

"Early-onset CRC in patients aged 18 to 29 years was shown to be unique, and patients with IBD may also have tumors with a unique biology. These notable differences in very young patients with CRC and those with predisposing conditions highlight that early-onset CRC has unique subsets within the population of patients younger than 50 years," they conclude.

"Going forward, special clinical consideration should be given to, and further scientific investigations should be performed for, both very young patients with colorectal cancer and those with predisposing medical conditions," Dr. Loree added in the news release.

The study had no commercial funding and the authors have no relevant conflicts of interest.

SOURCE: http://bit.ly/2T0eYWa

Cancer 2019.

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