When it comes to cancer, early detection can make a significant difference. Understandably, many people want to know whether a simple blood test can provide peace of mind. You may have searched online or heard someone say that their “bloods were normal, so there’s nothing to worry about.” But can a blood test detect cancer, and if so, how reliable is it?

At our Darwen and Grove branches, we often speak to patients who are confused or concerned about what blood tests can truly tell them. In this article, we aim to separate myths from facts, and provide clear, practical insight into how blood tests relate to cancer detection.

Myth 1: A Normal Blood Test Means You Don’t Have Cancer

Fact: While some cancers may cause abnormalities in blood tests, many do not—especially in the early stages.

One of the most common misconceptions is that if your routine blood tests come back “normal”, you must be cancer-free. Unfortunately, that isn’t always true. Most standard blood tests, such as a full blood count (FBC) or liver function test, are not designed to screen for cancer specifically. They can sometimes highlight indirect signs that warrant further investigation, but they are not diagnostic on their own.

For example, a slightly raised white blood cell count might indicate an infection—or, in rare cases, something more serious. But a normal result does not guarantee you are clear of cancer.

Myth 2: Blood Tests Can Detect Any Type of Cancer

Fact: Blood tests are useful for certain cancers—but not all.

There are specific types of cancer that may be picked up on blood tests more reliably than others. These include:

Leukaemia: Often detected through abnormalities in a full blood count, such as very high or low white blood cell levels or the presence of immature cells.

Multiple myeloma: May show up via high calcium levels, abnormal protein levels, or kidney function tests.

Liver cancer: Abnormal liver function tests or raised levels of a protein called alpha-fetoprotein (AFP) may be indicators.

Prostate cancer: Often monitored using a prostate-specific antigen (PSA) blood test, although PSA levels can also be raised due to non-cancerous conditions.

Ovarian cancer: May show raised levels of CA-125, though this marker can also increase in benign conditions.

It’s worth noting that no single blood test can detect all cancers. Many solid tumours—such as breast, lung, or bowel cancer—may not be detected via blood tests at all, especially in early stages.

Myth 3: Tumour Markers Are Definitive for Diagnosing Cancer

Fact: Tumour markers can support a diagnosis—but they are not conclusive.

Tumour markers are substances produced by cancer cells, or by the body in response to cancer. While some are useful for monitoring the progression or recurrence of a known cancer, they’re rarely used as standalone diagnostic tools.

This is because:

• –> Tumour markers can be elevated in non-cancerous conditions

• –> Not all cancers produce tumour markers

• –> A normal marker level does not rule out cancer

Doctors use tumour marker tests as part of a bigger picture, often alongside imaging, biopsy, and symptom history.

Myth 4: Blood Tests Are a Waste of Time for Cancer Detection

Fact: While not perfect, blood tests are a valuable starting point.

While it’s true that blood tests alone can’t provide a definitive answer in most cases, they are extremely useful in guiding further investigation. A set of abnormal results might alert a GP or specialist to look more closely—potentially prompting an ultrasound, CT scan, or referral to a consultant.

Blood tests are also used to:

• –> Monitor ongoing treatment response in cancer patients

• –> Assess general health before treatment (e.g. chemotherapy or surgery)

• –> Detect side effects or complications of treatment

• –> Provide reassurance or highlight red flags when combined with symptoms

When Should You Have a Blood Test for Cancer Concerns?

If you’re experiencing unexplained symptoms—such as persistent fatigue, unintentional weight loss, new lumps, prolonged bleeding, or changes in bowel habits—it’s important to speak to a GP or healthcare professional. They may recommend a blood test as an initial step.

At our pharmacy, we offer private blood testing in Lancashire, including:

• –> Full blood count

• –> PSA (for prostate health)

• –> Liver and kidney function

• –> Inflammatory markers (CRP/ESR)

• –> Vitamin and hormone checks

These tests can help build a picture of your health and may indicate whether further investigation is needed. We’ll always advise you to follow up with a GP or specialist if we detect anything of concern.

So, can a blood test detect cancer?

In some cases, yes—but it’s more accurate to say that blood tests can suggest the possibility of cancer, rather than confirm or rule it out on their own.

They are an important part of the diagnostic process, but they must be interpreted in context—alongside symptoms, physical examinations, and imaging. If you’re concerned about your health, don’t rely on assumptions. Speak to a professional and take proactive steps to understand what’s going on.

For private blood tests in Lancashire, cancer risk assessments, or health screening advice, contact your local Everest clinic today. We’re here to help you take control of your health—one step at a time.

This blog was written on behalf of Everest Pharmacy by Pharmacy Mentor.