Up to 10% of colorectal cancers could be missed by current screening programs of people who have a family history of colon polyps. This is according to a study published in the journal Cancer.

Colorectal cancer (CRC) is the third leading cause of cancer-related death in the US according to the American Cancer Society. They estimate it will cause around 50,830 deaths this year.

It has long been known that if a person has a family history of adenomatous adenomas (polyps), they are at increased risk of developing colorectal cancer.

Researchers from the Huntsman Cancer Institute (HCI) at the University of Utah, question whether the current guidelines are enough to effectively detect colorectal cancer through screening, particularly for patients at higher risk.

Current colorectal cancer screening guidelines from the US Preventive Services Task Force (USPSTF) recommend that colonoscopy screening – a test that analyzes the inner lining of the large intestine – should begin at age 50, and continue every 10 years thereafter.

However, first-degree relatives of patients who were diagnosed with the cancer before the age of 60 – defined as parents, siblings or children of patients with adenomas or advanced adenomas – are recommended to undergo screening every 5 years from the age of 40.

But second- and third-degree relatives of patients who were diagnosed before the age of 60 – including uncles, aunts and grandparents – and first-degree relatives of those diagnosed over the age of 60, are advised to start screening at age 50 – the same age as the general public.

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While polyps may indicate a predisposition to colorectal cancer, they are often benign and easily removed.

To reach their findings, the HCI researchers analyzed 126,936 patients aged between 50 and 80 who underwent colonoscopy screening between 1995 and 2009. Of these patients, 43,189 has adenomas and 5,563 had advanced adenomas.

It was found that the risk of CRC was 35 – 70% higher for first-degree relatives of those diagnosed with adenomas or advanced adenomas, compared with relatives of those without the condition. Furthermore, a smaller but significant increased risk was found for colorectal cancer in second- and third-degree relatives.

From these results, the researchers found that if patients included in the study adhered strictly to current screening recommendations, around 10% of colorectal cancers would be missed.

“We expected to see increased risk in first-degree relatives, but we weren’t sure the risk would also be higher for more distant relatives in multiple generations,” says Dr. N. Jewel Samadder, an investigator at HCI and study author.

“The biggest surprise was the percentage of missed cancers under the current guidelines. We figured there would be a few percent, but 10% is a large number.”

Dr. Samadder says that these findings should be considered when considering CRC screening guidelines for individuals and their families:

Our results support the current screening guidelines, but they also raise the issue of whether some level of more aggressive screening should be considered, not only for first-degree relatives of patients with polyps diagnosed at or below age 60, but also for those first-degree relatives of patients diagnosed above age 60.”

Dr. Samadder notes that in order to validate other areas of the current screening guidelines, there needs to be more in-depth examination of the risk of colorectal cancer for relatives of patients diagnosed with CRC or advanced adenomas.

She adds this could be done by looking at the size of the polyp, the degree of cell abnormality and the location of the tumor within the bowel.

Medical News Today recently reported on a study revealing that certain gene variations could indicate colon cancer.