Adults should start screening for colorectal cancer at age 45

The U.S. Preventive Services Task Force (USPSTF) recent draft recommendation statement proposed that "Adults should start screening for colorectal cancer routinely at age of 45 to 75, instead of waiting until 50 in a move that reflected the sharp rise of the number of colon and rectal cancers in young adults.

Though the vast majority of colorectal cancers are still found in the those of 50 and older, 12 percent of the 147,950 colorectal cancers that will be diagnosed this year, approximately 18,000 cases, will be found in adults under the age of 50.

The American Cancer Society in a statement issued in 2018 recommended starting at 45, after researchers found a sharp rise of the disease among young adults as young as in their 20s and 30s, including a sharp rise in rectal cancers.

The proposal by the USPSTF still must be finalised.   Its guidance on screenings and preventive care services is followed by doctors, insurance companies and policymakers.  

Low Radiation Dose CT Leads to Inferior Diagnoses

Jensen et al reported in Radiology that CT evaluation of colorectal liver metastases was not as accurate after reducing the radiation exposure by more than 50 percent. 

Their study included 52 patients with biopsy-proven colorectal cancer liver metastases and few benign lesions as well.  Each patient underwent two CT scans-a standard radiation dose (SD) contrast CT and a reduced radiation dose (RD) CT scan- during the same breast hold.

Reduced dose CT resulted in a mean dose reduction of 54% compared with standard dose. Of the 260 lesions, 233 were metastatic and 27 benign, 212 were detected with RD CT, whereas 252 were detected with SD CT.   Mean qualitative scores ranked SD images as higher quality versus RD series images.

The authors concluded that CT evaluation of colorectal liver metastases is compromised with reduced radiation dose, and the use of iterative reconstructions could not maintain observer performance.

New Guidelines for Colon Cancer Screening Tests.

Colorectal cancer is the second leading cause of cancer death in the United States. In 2016, an estimated 134 000 persons will be diagnosed with the disease, and about 49 000 will die from it. Colorectal cancer is most frequently diagnosed among adults aged 65 to 74 years; the median age at death from colorectal cancer is 68 years.

The United States Preventive Services Task Force (USPSTF) reviewed the evidence on the effectiveness of screening with colonoscopy, flexible sigmoidoscopy, computed tomography colonography, the guaiac-based fecal occult blood test, the fecal immunochemical test, the multi-targeted stool DNA test, and the methylated SEPT9 DNA test in reducing the incidence of and mortality from colorectal cancer or all-cause mortality; the harms of these screening tests; and the test performance their characteristics for detecting adenomatous polyps, advanced adenomas based on size, or both, as well as colorectal cancer.

The USPSTF concluded with high degree of certainty that screening for colorectal cancer in average-risk, asymptomatic adults aged 50 to 75 years is of substantial net benefit. Multiple screening strategies are available to choose from, with different levels of evidence to support their effectiveness, as well as unique advantages and limitations, although there are no data to demonstrate that any of the reviewed strategies provide a greater net benefit.

USPSTF recommends screening for colorectal cancer starting at age 50 years and continuing until age 75 years (A recommendation).  Individuals should pick the screening test they feel the most comfortable with.  The decision to continue screen for colorectal cancer in adults aged 76 to 85 years should be an individual one, taking into account the patient’s overall health and prior screening history (C recommendation).