Colorectal cancer (CRC), more commonly called colon cancer, is currently the second-leading cause of cancer-related death in the U.S. But studies find it’s also highly treatable, especially if it’s caught early. Now, a new blood test might make it much easier (and cheaper) to screen for signs of colon cancer.

This morning, the U.S. Food and Drug Administration (FDA) approved Guardant Health’s CRC blood test, Shield, which scans for signs of cancer in adults aged 45 and over. Although the test is not meant to replace traditional colonoscopies, the approval marks the first time any blood test has been given the go-ahead as a primary screening option for CRC, as well as the first time any CRC blood test has met the requirements for Medicare coverage. That means the test could soon be much more affordable for millions of older patients.

Here’s everything you need to know about Shield:

How does the Shield colon cancer test work?

Shield is a noninvasive blood test, meaning that it doesn’t require any of the intensive prep work (like extended fasting) needed for a colonoscopy. It detects cancers by seeking out the DNA that cancerous tumors release into the bloodstream. The test is administered at the doctor’s office, and should be repeated every three years after the age of 45.

According to a 20,000-patient study published in The New England Journal of Medicine in March, Shield was 83% effective in identifying colon cancer. The test was less sensitive to discovering earlier-stage polyps, which it found only 13% of the time. Doctors emphasize that Shield is only a first step: If the test finds potential cancer markers, a colonoscopy would be necessary to confirm the diagnosis and understand the severity of the case.

How much does it cost?

Prior to FDA approval, the test’s self-pay price was a steep $895. However, with the approval, Shield is much more likely to be covered by private insurance companies and by Medicare plans for patients 65 and older.

Guardant Health told Fast Company that “once coverage is established, eligible Medicare Part B beneficiaries won’t have any out-of-pocket cost,” while the out-of-pocket cost for Medicare Advantage beneficiaries “will vary depending on their individual plans.” The cost of the Shield test for patients with commercial insurance plans also may vary depending on individual plan coverage.

Guardant Health added that “the self-pay price for the FDA-approved version of the test will be available when we launch the test commercially, which we expect to happen within the next week.”

What are my other options?

The company Exact Sciences offers a feces-based screening test called Cologuard. There’s also another blood test called Epigenomics’ Epi proColon, which was FDA approved in 2016, but that test did not meet the standards to be approved for Medicare coverage due to testing beneath the 74% cancer detection threshold.

And, of course, traditional colonoscopies are still the best method for detecting colon cancer.

What do I need to know about colon cancer?

Per a press release from Guardant Health, the colon cancer screening rate in the U.S. is around 59%—well below the National Colorectal Cancer Roundtable’s goal of 80%. “More than one out of three eligible Americans—over 50 million people—do not complete CRC screening, often due to the perception that other available options, such as colonoscopy or stool-based tests, are invasive, unpleasant or inconvenient,” the release reads.

But screening for CRC early and often can make a major difference for patients. “When colon cancer is found at an early stage before it has spread, the five-year relative survival rate is 91%,” the release states. “If the cancer has spread to distant parts of the body, the five-year relative survival rate is 14%.”

In an interview with NBC News, Dr. Sapna Syngal, director of strategic planning for prevention and early cancer detection at the Dana-Farber Cancer Center in Boston, said the “biggest problem” with colon cancer right now is that many Americans aren’t getting screened.

“If this test increases the number of people getting screened, it’s going to have a huge impact,” she said.