Parent or Sibling With Colon Cancer? You May Need Colonoscopy Earlier
If colon cancer runs in your family, screening at age 40 might help catch the disease at an early stage, or even prevent it, specialists say.
But a new investigation suggests that that advice is rarely heeded among those who go on to develop colon cancer before age 50.
"We need better public awareness of the importance of family history, and systems put in place to help make sure that family history is collected and acted upon," said study lead author Dr. Samir Gupta. He's a professor of clinical medicine at University of California, San Diego Health and Moores Cancer Center in La Jolla, Calif.
Gupta's team followed nearly 2,500 patients who were diagnosed with colon cancer in their 40s.
About a quarter had first-degree family members -- siblings or parents -- who had also battled the disease. The American Cancer Society advises such individuals to start screening either at age 40, which would be five years earlier than those at average risk, or 10 years before the age of diagnosis for the youngest relative with the cancer.
But the study team found that more than 98% hadn't had early screening, as their cancer diagnosis happened after the point when an initial high-risk screening would have taken place. And that failure likely represents a missed opportunity to catch colon cancer at a more treatable stage -- or prevent some cancers altogether.
"Why this is happening is not well-understood," said Gupta.
But Gupta suggested it might be due to a lack of appreciation, on the part of patients and their doctors, for the significant role that family history plays in predicting colon cancer risk.
Colon cancer is the second leading cause of cancer death in the United States. And the study team points out that colon cancer rates have been rising among adults younger than 50. Why that's happening is also "not well-understood," said Gupta.
However, the cancer society also notes that about a third of colon cancer patients have family members who've had colon disease, and should therefore get screened at 40 either with a stool test or colonoscopy.
Besides the study participants who had colon cancer, the new investigation included a pool of nearly 800 who did not have cancer. All had enrolled in the Colon Cancer Family Registry between 1998 and 2007. The registry collects cancer risk data on more than 15,000 families across the globe.
One in 4 of the cancer patients had a family history of colon cancer, as did 1 in 10 of the healthy patients. But less than 2% of the patients diagnosed with colon cancer appeared to have followed family-based screening guidance.
"The study," said Gupta, "did not have access to information on whether the [cancer] cases or [healthy] controls in fact did have their family histories ascertained by physicians, whether the guidelines were considered, and whether early screening was recommended or not."
But "from other studies," he added, "we know family history of cancer is often not collected, and even when collected that it is not collected accurately."
That concern was echoed by Dr. Andrew Chan, an associate professor of medicine at Harvard Medical School, who reviewed the findings.
"This study suggests that patients may not be aware of their family history, or communicating it accurately to their physicians," he said. "Physicians in turn need to make sure they ask their patients about family history of colorectal cancer, including the age at which a family member was diagnosed.
"Based on this information," added Chan, "physicians need to recommend screening at the right time for that patient, and the patient needs to follow through in a timely way."
Gupta suggested there are ways to use existing technology to boost guidance compliance. For example, he said, "electronic health record triggers" could be deployed to "remind the health care team to take a family history, and have algorithms built in, which 'flag' patients who need specialized screening."
Meanwhile, Gupta said, the bottom line is simple: "Know your cancer family history. And tell your doctor. It could be lifesaving for you or one of your family members."
The findings are in the April 20 online issue of Cancer.
There's more about colon cancer screening recommendations at the American Cancer Society.
SOURCES: Samir Gupta, M.D., MSCS, AGAF, professor, clinical medicine, division of gastroenterology, department of internal medicine, and co-lead, Cancer Control Program, Moores Cancer Center, and VA San Diego Healthcare System, and University of California, San Diego; Andrew Chan, M.D., M.P.H., associate professor, department of medicine, Harvard Medical School, and associate professor of medicine, gastroenterology, Massachusetts General Hospital, Boston; April 20, 2020, Cancer, online