Colon cancer seen via a radial CT scan. Photo: BSIP/UIG via Getty Images

The intensive testing currently prescribed to colorectal cancer patients after initial treatment doesn't significantly improve their survival chances or the detection of recurrence, according to two separate studies published Tuesday in the Journal of American Medical Association.

What it means: Researchers from both studies are urging an update to current guidelines to lessen the intensity of testing unless the patient is in a high-risk category.

Background: Colorectal is the second leading cause of cancer death in the U.S. and is expected to affect more than 140,000 people in 2018.

  • Right now, guidelines from the National Comprehensive Cancer Network and the American Society of Clinical Oncology recommend a medical history, physical exam and carcinoembryonic antigen testing be performed every 3 to 6 months for 5 years after first being treated for these cancers.

Yes, but: Unnecessary testing can offer its own risks, like exposure to more radiation, false positives, and painful and costly procedures, both studies pointed out.

The studies:

1. University of Texas MD Anderson Cancer Center study examined the primary records of more than 8,500 patients with stage I, II, or III colorectal cancer after they received their primary treatment.

  • What they found: There was no significant association between the frequency of surveillance testing and when a cancer recurrence was detected.
  • "There is limited 'real' evidence to guide these [testing] recommendations," study author George Chang tells Axios, and this has led to large variations in surveillance globally.
  • New technologies are being developed, Chang points out, that could help personalize medicine to each patient so there's less of a need to take a "one size fits all" approach.

2. Aarhus University Hospital in Denmark conducted a randomized clinical trial of more than 2,500 patients in Denmark, Sweden, and Uruguay with stage II or III colorectal cancer. They compared mortality rates of those who had more frequent followup testing with imaging and blood tests with those who had less frequent followup testing.

  • What they found: The 5-year mortality rate from colorectal cancer was 10.6% in the higher frequency group, and 11.4% in the lower frequency one.
  • They also found that among people receiving high-intensity testing, colorectal cancer– specific recurrence was detected earlier, but it didn't translate into a reduced mortality rate.
  • "We speculate the following: recurrence from colorectal cancer can occur at many sites — such as the liver, pelvis, peritoneum, and lungs. For these patients, salvage surgery is challenging and probably less than half are suitable for surgery," according to study author Andrew Renehan.
  • He says, "There is currently wide variation in CT scan scheduling. This usually implies that health services and resources are being used inefficiently. This trial should make follow-up more uniform, and in many settings, will probably be cost-saving."

Limitations: In an editorial published with the studies in JAMA, Hanna K. Sanoff, of the University of North Carolina-Chapel Hill, writes both of these studies have design limitations, but when combined with a smaller study done in 2014:

"[T]here is now a considerable body of evidence that imaging and CEA testing more often than every year does little to improve survival in a meaningful way."

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