Tumour markers during chemotherapy

Sometimes, for some cancers, and only as part of the picture. Tumour markers are substances that certain cancers release into the blood, such as CA-125 in ovarian cancer, CEA in bowel cancer, CA 19-9 in pancreatic and bile duct cancers, AFP and beta-hCG in some testicular and liver cancers, and PSA in prostate cancer. When a cancer that makes a marker is responding to treatment, the level often falls over time. Your team uses these trends alongside scans, examination and symptoms to judge response.

But markers are imperfect. Not every cancer makes a marker, and some people with cancer have normal levels. Markers can rise for reasons that have nothing to do with cancer, such as infection, inflammation, liver or kidney problems, smoking, menstruation or recent procedures. They can even rise briefly at the start of successful treatment as cancer cells break down, called a surge or flare. Many people track every result anxiously and panic over normal ups and downs. A single result rarely changes a plan. This page explains markers. It cannot interpret your own results, which your team must do.

Trends matter more than one number

Your team looks at the direction over several tests, not one reading.

Scans still matter

Treatment decisions are usually based on scans and symptoms as well as markers.

Use the same lab

Different labs can give different values for the same marker, which can look like a change when there is none.

It cannot tell you whether a marker result means your treatment is working or not. That judgement depends on your cancer type, whether your cancer makes that marker, the trend, your scans and your symptoms. A rise or fall on its own is not enough.

It also cannot tell you whether to change treatment. Decisions to continue, change or stop treatment are made by your oncologist, usually with scans, never on one marker result.

Marker flare at the start of treatment

In some cancers, markers rise briefly in the first weeks of effective treatment before falling. Your team knows to expect this.

Normal markers do not rule out cancer

Some cancers never raise markers, so a normal level does not mean there is no cancer.

Markers are not screening tests

Most markers are not reliable for finding cancer in healthy people. They are mainly used to follow known cancers.

Private testing without advice

Ordering extra marker tests yourself can create confusing results. Ask your team which tests are useful.

After treatment

Markers may be part of follow-up for some cancers. A small rise is usually rechecked before any conclusion.

Costs add up

Marker tests can be expensive. Ask how often they are genuinely needed for your cancer.

Family worry

Relatives may focus on marker numbers. Share your team's explanation so everyone understands what matters.

Keep reports with scan results

Filing markers alongside scan reports helps doctors see the full picture.

Ask what would change the plan

It is reasonable to ask what kind of marker change would lead your team to arrange a scan.

Timing of the test matters

Markers can be affected by when the sample is taken, for example soon after surgery, a procedure, an infection or a cycle of treatment. Your team may time marker tests to give the most useful information, often before a cycle rather than straight after one.

Markers and emotions

Waiting for a marker result can bring anxiety for days. Some people find it helps to agree with their team when and how results will be shared, so they are not left reading reports alone late at night.

Different cancers, different roles

In some cancers markers are central to follow-up, while in others they are rarely used. The way a friend with a different cancer uses markers may not apply to you.

Rising markers after treatment

If a marker slowly rises during follow-up, your team usually repeats it and may arrange a scan. A single rise is not a diagnosis, and there is usually time to check carefully.

What to do next

Ask whether markers are useful for your cancer, use the same lab, mention infections or procedures around tests, let your team interpret trends with scans, avoid tracking every result alone, and act on symptoms rather than waiting for markers.