A simple blood test that could detect colorectal cancer in its earliest stages has been approved for use in the US. 

Colorectal cancer is the second-leading cause of US cancer deaths, leading to about 55,000 fatalities every year, and cases are rising among under-50s, for whom the disease is now the leading cause of cancer-related death.

The FDA signed off on the test, called SimpleScreen CRC, which is designed to detect DNA signals in the blood that may indicate the cancer. 

Developed by California-based company Freenome, it was approved for adults aged 45 years and over who have an average risk of the cancer.

In trials, the test detected about eight in 10 colorectal cancer cases on average. It correctly detected nearly 60 percent of early-stage colorectal cancers and 100 percent of stage two cancers, when the disease has grown into the wall of the colon but has not yet spread.

The test is not meant to replace colonoscopies – the gold standard for screening – but doctors believe it could help them to detect more cases early, when they are more easily treated.

US health officials recommend everyone is screened for colon cancer from age 45 years using a colonoscopy, but one in three eligible adults do not get the tests, surveys suggest. 

Colonoscopies require patients not to eat solid foods for 24 hours before the screening is carried out.

In tests involving 48,000 people, doctors also found that it correctly ruled out colorectal cancer in nine in 10 patients. 

The test is set to become available this fall, although no details on how much it costs have been revealed. It may be covered by some health insurance plans.

'The most effective screening test is the one a person will actually complete, but many people who should be screened for colorectal cancer simply aren't,' said Dr Aasma Shaukat, a medicine researcher at NYU who led research into the test.

'A blood-based test provides another way to reach unscreened patients, and bringing more people into the screening fold leads to earlier detection and better outcomes.'

'Today's approval is an important validation of the scientific vision we've spent more than a decade building,' said Aaron Elliott, CEO of Freenome.

It is the second blood-based test for colorectal cancer to be approved in the US, after Shield, a test by California-based Guardant Health, was also given the green-light by the FDA in July 2024.

This test, costing about $900 but covered by some health insurance plans, also works by screening for DNA in the blood that could be from cancerous tumors. 

Guardant Health recommended that it should be administered once every three years to people from the age of 45 years. It should not be used in the place of a colonoscopy. 

Praising the approval of the new blood test, Anjee Davis, CEO of non-profit Fight Colorectal Cancer, said: ‘The fact is that 90 percent of colorectal cancer deaths are preventable.

‘Regular screening is the key to reversing that trend, and new, minimally invasive screening options that help more people get screened are a critical part of that process.’

The American Cancer Society projects nearly 109,000 new cases of colon cancer and close to 50,000 new cases of rectal cancer will be diagnosed this year alone, with more than 55,000 deaths forecast in 2026.

Currently, up to 60 million Americans who should be screened for colorectal cancer remain overdue, according to surveys.

The convenience of a blood-based test could help overcome barriers that keep people from undergoing more invasive procedures like colonoscopies, which many patients avoid due to the preparation requirements and the invasive nature of the procedure.

Clinical validation for the test came from the PREEMPT CRC study, the largest prospective study ever conducted for a blood-based colorectal cancer screening test.

The study enrolled more than 48,000 asymptomatic, average-risk adults aged 45 to 85 who were scheduled for screening colonoscopies.

The later colorectal cancer is detected, the less likely it is that treatment will be able to clear the disease.

About 91 percent of patients who have the cancer detected in its earliest stages live for five years or more after diagnosis, statistics suggest. 

For comparison, when the cancer is not detected until stage four – when it has spread to other areas in the body – only 13 percent of patients live for five years or more. 

This stark difference in survival is the key reason why early detection through screening is so important.

Experts caution that these blood tests have significant limitations compared to the gold standard of colonoscopy.

A clinical trial of Shield, another blood test that screens for colorectal cancer in adults aged 45 and older who are at average risk for the disease, which received FDA approval in July 2024, found it was less effective at detecting Stage 1 colorectal cancers, missing 35 percent of cases.

SimpleScreen CRC detected 52 percent of Stage I cancers in its study. Both tests also showed poor detection rates for precancerous polyps, finding only about 13 percent of them.

Colonoscopy remains the only test that can both detect and remove polyps, thereby preventing cancer from developing in the first place.

With Medicare coverage expected and incorporation into American Cancer Society guidelines anticipated, SimpleScreen CRC may help bridge the screening gap, even as experts stress that any abnormal result must be followed up with a confirmatory colonoscopy.