Proactive Blood Tests That Help Detect Cancer Early

— A Re-Femme Guide for Women Navigating Modern Cancer Screening

Today’s technology allows us to detect cancer signals through a simple blood draw — sometimes before a tumor ever shows up on a scan. These tests are not “diagnostic,” meaning they cannot confirm cancer on their own, but they are powerful tools for early detection, monitoring recurrence, and guiding conversations with your care team.

This guide breaks down the most widely used proactive blood tests — including Galleri, Signatera, and other circulating tumor DNA (ctDNA) and minimal residual disease (MRD) tests — and explains who qualifies, what they do, and what they cannot tell you.

What Are Proactive Blood Tests for Cancer?

These tests look for fragments of tumor DNA in your bloodstream, called circulating tumor DNA (ctDNA). All humans shed DNA into their blood, but cancer cells shed DNA in different patterns. These tests analyze those patterns to determine whether cancer signals may be present.

They fall into two major categories:

• Multi-cancer early detection tests (MCED) — broad screening tests for people with no symptoms.
• MRD / recurrence-monitoring tests — personalized tests for people who already have (or had) cancer.

These tests are not replacements for mammograms, colonoscopies, pap smears, ultrasounds, or biopsies. Instead, they offer added insight, especially for high-risk patients or survivors monitoring for recurrence.

1. The Galleri Test (by GRAIL)

Type: Multi-cancer early detection (MCED) test

Purpose: Screens for signals associated with more than 50 types of cancer from a single blood draw.

Who Qualifies?

Galleri is designed for adults 50 and older, or for younger adults with a high risk of cancer due to:

• Genetic mutations (BRCA1/2, CHEK2, TP53, etc.)
• Strong family history of cancer
• Previous cancer diagnosis (although it is not intended for recurrence monitoring)
• Environmental risk factors

Because you are triple-positive breast cancer (ER+/PR+/HER2+), Galleri can be used as an additional screening tool, but it is not specific for monitoring breast cancer recurrence. It can help detect cancer signals anywhere in the body, but your oncologist may prefer ctDNA tests that are personalized to your tumor.

What Galleri Can Tell You:

• Whether cancer-associated DNA patterns are detected
• The most likely tissue where the signal originated

What Galleri Cannot Do:

• Diagnose cancer
• Find extremely small tumors in every case
• Replace standard screening like mammography

2. Signatera (by Natera)

Type: Personalized ctDNA test for MRD and recurrence monitoring

Purpose: Detects whether any cancer DNA remains after treatment or if recurrence is starting to develop.

Who Qualifies?

Signatera is designed for patients who have already had a cancer diagnosis and:

• Have completed chemotherapy, surgery, or radiation
• Have measurable disease or are in remission
• Are being monitored for recurrence

It is especially used for breast cancer, colorectal cancer, lung cancer, and other solid tumors. Many triple-positive women use Signatera for recurrence monitoring, but each oncologist has their own approach.

Important: Insurance typically requires a diagnosis code and a clear clinical reason for ordering the test.

What Signatera Can Tell You:

• Whether your specific tumor DNA is still circulating
• If recurrence may be starting long before a scan shows anything
• Whether treatment was effective

What Signatera Cannot Do:

• Screen for cancers you haven’t had
• Replace standard imaging (PET/CT, MRI, mammogram)
• Guarantee detection of every recurrence

3. Other ctDNA and MRD Monitoring Tests

There are several other tests used across oncology for recurrence monitoring:

• Guardant Reveal – recurrence monitoring for colorectal and other cancers
• Tempus xF+ – ctDNA profiling for treatment decisions
• Invitae Personalized MRD – tumor-informed ctDNA monitoring
• Labcorp OmniSeq – genomic profiling for targeted therapy decisions

These tests may be used depending on cancer type, genetics, stage, and insurance coverage. Breast cancer patients — especially hormone-driven cancers like triple-positive — often use Signatera or similar MRD tests to help monitor response and recurrence risk.

Do You Need a Diagnosis to Qualify?

It depends on the type of test:

For Galleri (Screening Test):

• You do not need a cancer diagnosis.
• You generally need to be 50+ or at increased risk.
• Insurance rarely covers it — it is often an out-of-pocket test ($949–$1,000).

For Signatera and other MRD tests:

• You do need a cancer diagnosis.
• Your oncologist must order it.
• Insurance may cover it with the correct ICD-10 code.

These tests are not interchangeable — Galleri looks across the body for cancer signals, while Signatera monitors your unique tumor DNA after diagnosis.

How to Talk to Your Oncologist About These Tests

Here are simple questions to ask:

• “Should I be using a ctDNA or MRD test for recurrence monitoring?”
• “Do you recommend Signatera or another test for my cancer type?”
• “Would a multi-cancer early detection test like Galleri make sense for me?”
• “How often should I repeat ctDNA testing during follow-up?”
• “Will my insurance cover this?”

Many oncologists are becoming more comfortable using ctDNA tests, especially for women who want to feel proactive about monitoring.

Where These Tests Fit in Survivorship

For women in survivorship or active surveillance, proactive blood testing can offer:

• Earlier warning signs of recurrence
• Reassurance when ctDNA is negative
• More personalized follow-up planning

But remember: a blood test is one piece of a much bigger picture. Your symptoms, scans, labs, and clinical exams are equally important.

A Re-Femme Action Step for Women Seeking Peace of Mind

These tests can feel overwhelming — and expensive — especially when insurance doesn’t cover them. If you’re exploring Galleri, Signatera, or other MRD tests, your community can help support you through your personalized Re-Femme registry.