How to identify colon cancer through blood tests

A simple blood test that detects subtle changes in the genetic code can identify people who are at higher risk of developing colon cancer than the general population, report Feinberg and others from the Kimmel Cancer Center of Johns Hopkins University in the United States.

Approximately 155,000 people in the United States develop colon cancer each year. Previous studies have shown that a phenomenon called loss of imprinting (LOI) is associated with several cancers. The LOI genetic defect, which occurs in the IGF2 gene, is present in ≥ 40% of colon cancer patients. Feinberg et al. conducted a study to see if LOI is associated with colon cancer.

The study included blood samples from 172 patients undergoing colonoscopy. Among them, 25 patients had a family history of colon cancer and polyps, or had a history of colon cancer and polyps themselves, and their blood LOI test was positive. The researchers found that the positive rate of blood LOI markers in patients with a family history of colon cancer was more than 5 times that of patients without a family history of colon cancer. The positive rate of blood LOI markers in patients with polyps increased by almost 3.5 times, and the positive rate of blood LOI markers in those with a history of colon cancer increased by more than 22 times. The study also found that in the 25 patients with positive blood LOI markers, LOI could be detected in all colon tissues on both sides.

Feinberg et al. said: "We hope that just like the method of identifying people at high risk of heart disease, this test can also help us identify people at high risk of colon cancer, closely follow up and prevent them, or at least help us diagnose colon cancer patients at an early stage." However, this blood genetic marker test can only be used for research at present. Feinberg et al. said that it may take many years to develop an effective test method. Finally, he added: "We also need to follow up patients to observe whether those who test positive for blood LOI will actually develop cancer in the future.