Do Blood Tests Find Cancer: What You Need to Know
As new testing methods continue to evolve, many people are asking the same thing: Do blood tests find cancer? While traditional screenings like scans and biopsies are still common, blood-based tools are becoming more popular for detecting certain cancers early.
These tests are less invasive and can sometimes spot warning signs before symptoms appear. Today, we’re taking a closer look at how blood tests are used for cancer detection, what they can reveal, and how accurate they truly are.
Understanding Cancer Detection
Cancer doesn’t always show symptoms early. Traditional methods are still the most common tools doctors use to find cancer. These include:
- Imaging scans like X-rays, MRIs, and CT scans
- Tissue biopsies to test for cancer cells
- Physical exams and routine checkups
Imaging Scans Like X-Rays, MRIs, And CT Scans
These scans help doctors see inside the body. They can find tumors, lumps, or changes in tissues. Sometimes scans are ordered based on symptoms, and other times they’re part of regular screening for higher-risk patients.
Tissue Biopsies to Test for Cancer Cells
A biopsy takes a sample of tissue from the body to look for cancer under a microscope. It’s one of the most accurate ways to confirm a diagnosis. Doctors often use biopsy results to decide on treatment options.
Physical Exams and Routine Checkups
A doctor may feel for lumps or notice other signs during a regular visit. While physical exams aren’t always enough to detect cancer, they help spot problems that might need more testing.
Do Blood Tests Find Cancer?
Many people wonder if a simple blood test can actually detect cancer. The answer is yes, in some cases. But the full picture is a little more complex.
Blood tests can help doctors find signs that point to certain types of cancer, though they don’t always give a clear answer right away. These tests look for markers or changes in the blood that may suggest a cancer is growing in the body.
Some blood tests are used to detect proteins or other substances linked to specific types of cancer. These are known as cancer biomarkers. For example, PSA levels can be used to help detect prostate cancer, while CA-125 may be used when screening for ovarian cancer.
Doctors also use newer tests that can look for small bits of tumor DNA in the blood. These are sometimes called liquid biopsies. These tests can be useful, especially for finding cancers before symptoms start.
That said, blood tests aren’t perfect. They don’t work for every cancer.
Some types don’t release any markers into the blood. Other times, markers can appear for non-cancer reasons.
So, while blood tests are helpful, doctors usually need to combine them with other screening tools.
Common Blood Tests Used in Cancer Detection
Doctors use different types of blood tests to help find signs of cancer. These tests don’t always confirm if cancer is present, but they can give strong clues.
Some look at blood cell counts, others check for proteins or pieces of tumor DNA. Each test has its own purpose, and some are more useful than others depending on the cancer type.
The most common ones include:
- Complete blood count (CBC)
- Tumor marker tests
- Liquid biopsy tests
Complete Blood Count (CBC)
A CBC checks the number and types of cells in your blood. It’s often used as a basic test to look for signs of problems.
In some cancers, like leukemia or lymphoma, abnormal blood counts may be the first warning sign. A very high or very low number of white blood cells, red cells, or platelets can show that something may be wrong.
Tumor Marker Tests
These tests look for cancer biomarkers, which are proteins made by cancer cells. For example, PSA is linked to prostate cancer, and CA-125 is linked to ovarian cancer.
These markers can help doctors monitor cancer over time or decide if more testing is needed. They aren’t perfect, though. Some people with cancer have normal levels, and some without cancer may have high levels.
Liquid Biopsy Tests
This newer type of test looks for bits of DNA that cancer cells release into the blood. These are called circulating tumor DNA, or ctDNA.
Liquid biopsies may help find cancer earlier or track how a treatment is working. They can also help doctors learn more about a tumor without needing to take a tissue sample.
How Accurate Are Blood Tests for Cancer?
Blood tests can give helpful clues when doctors are checking for cancer, but they are not always right. To understand how useful these tests are, doctors look at two main things: sensitivity and specificity.
Sensitivity means how well a test finds cancer when it’s actually there. A test with high sensitivity picks up most cases without missing many.
This matters in early cancer detection, where missing signs can delay treatment. On the other hand, specificity shows how well the test avoids false alarms.
A test with high specificity doesn’t say you have cancer unless there’s real cause to think so. When a test has low specificity, it might lead to more tests that aren’t needed.
False positives can cause worry and lead to more medical visits. A false negative, where the test misses cancer, can be more serious. That’s why most doctors don’t rely on one blood test alone.
Diagnostic blood tests are best used with other tools like scans and physical exams. Together, they create a more complete picture.
The accuracy of blood tests will likely improve as new technology develops. Some newer tests that use cancer biomarkers or circulating tumor DNA are showing better results in trials.
Cancer Screening Methods
So, do blood tests find cancer? In many cases, they can point to early signs or support a diagnosis, but they’re usually part of a larger process.
At Precision Labs, we make lab testing easier for both patients and providers. Our certified phlebotomists offer flexible options, from in-office support to mobile blood draws. We’re focused on delivering accurate results on your schedule, helping you provide better care with less hassle.
Get in touch today to find out how we can help with your testing needs.