The rising incidence of colorectal cancer in adults younger than 50 years heightens the need to evaluate the colon and rectum of any patient, regardless of age, who presents with symptoms such as rectal bleeding, weight loss, abdominal pain, iron-deficiency anemia, or changes in bowel habits, according to a new American Gastroenterological Association clinical practice update.
In addition to receiving cancer staging or being referred to an oncologist, newly diagnosed patients should be counseled about both germline genetic testing and fertility preservation, wrote Lisa A. Boardman, MD, of Mayo Clinic in Rochester, Minn., with associates in Clinical Gastroenterology and Hepatology. “Clinicians should present the role of fertility preservation prior to [administering] cancer-directed therapy, including surgery, pelvic radiation, or chemotherapy.”
It remains unclear why the incidence of young adult–onset colorectal cancer is rising, but the trend is not limited to the United States. Implicated risk factors include inflammatory bowel disease, prior irradiation, harboring a pathogenic germline mutation for a known hereditary cancer syndrome, and having a first- or second-degree relative with colorectal cancer. Indeed, the odds of developing young adult–onset disease are nearly 4 times higher if a parent has colorectal cancer and nearly 12 times higher if a sibling is affected.
For newly diagnosed young adults, it is important to collect a family cancer history but vital, regardless of history, to discuss targeted or multiplex germline mutation testing. Detecting hereditary colorectal cancer syndromes is crucial because their nature informs surgical options for treatment. “Roughly one in five young adult–onset colorectal cancers will be caused by a germline mutation, and among those with a detectable hereditary condition, half of those patients with young adult–onset colorectal cancer will have Lynch syndrome,” the experts noted. For these patients (who have mutations involving MSH2, EPCAM, MLH1, MSH6, and PMS2), ileorectostomy (IRA) for colorectal cancer should be considered.
For patients with the classic subtype of familial adenomatous polyposis, ileal pouch anal anastomosis is recommended after the polyp burden can no longer be managed endoscopically, although initial IRA with subsequent conversion to IPAA is an option for women of child-bearing age, according to the clinical practice update. Patients with the attenuated subtype of familial adenomatous polyposis should consider IRA or colectomy if colorectal cancer develops or if the polyp burden exceeds endoscopic control. In contrast, colectomy is the only type of surgery recommended for patients with serrated polyposis syndrome requiring surgical treatment.
Finally, clinicians should offer only screening for hereditary cancer syndromes if young adults cancer have been diagnosed with a hereditary colorectal cancer syndrome. “For patients with sporadic young adult–onset colorectal cancer, extracolonic screening and colorectal cancer surveillance intervals are the same as for patients with older adult–onset colorectal cancer,” the experts wrote. For young patients without an apparent underlying genetic syndrome, molecular studies may eventually help tailor treatment options, “but at this point, more extensive surgery or more aggressive chemotherapy cannot be recommended. As cancer treatments evolve to use patient tumor specific therapeutics, our management of patients with young adult–onset colorectal cancer will improve.”
Dr. Boardman and associates reported having no relevant conflicts of interest.
SOURCE: Boardman LA et al. Clin Gastroenterol Hepatol. 2020 Jun 7. doi: 10.1016/j.cgh.2020.05.058.