After treatment

Blood tests after cancer treatment

During treatment somebody measured you constantly. Then it stops — and nothing replaces it for the thing you now have most control over.

Before chemotherapy, many people are given an echocardiogram. A baseline of the heart, because the drugs about to be administered can damage it, and you cannot detect damage without knowing where you started.

Baseline. Intervene. Re-measure. It is ordinary oncology, and almost everyone who has been through treatment has experienced it without necessarily noticing it as a method.

Then treatment ends, and nobody applies that logic to anything you do for yourself — for the rest of your life ahead.

The distinction that matters

There are two entirely different things a blood test can be doing, and confusing them causes real harm.

Surveillance is watching for the disease coming back. That is your treating team’s job. It follows a schedule they set based on your specific diagnosis, and no website, app or journal should be involved in it.

Measurement is seeing what your own behaviour does to your own biology. Inflammation, metabolic markers, nutritional status. Nobody schedules this for you, because it was never anybody’s job.

Skip It Out is entirely the second thing. It does not monitor for recurrence and cannot be used that way.

What is worth measuring

Through most public health systems, a cancer history provides clinical justification for a substantial panel at little or no cost. Broadly it covers:

• Inflammation — hs-CRP, IL-6 and related markers, the ones most directly responsive to exercise and diet change
• Immune function — full blood count, immunoglobulins, and viral markers including EBV
• Thyroid and hormones — frequently disrupted by treatment, frequently unexamined afterwards
• Liver function — after months of processing cytotoxic drugs
• Vitamins and minerals — vitamin D, B12, iron studies
• Metabolic markers — glucose, HbA1c, lipids
• Bone turnover — CTX and P1NP, which unlike bone density can shift within ninety days

Beyond that there is a deeper tier available privately — NK cell activity, heavy metals, gut health panels, environmental toxins, omega-3 index. Useful, optional, and entirely a question of budget.

How to get the request written

Start with your oncologist or treating specialist. In most health systems a specialist request carries fewer restrictions than a GP request, so the whole panel can usually go on one form. If you are still attending follow-up appointments, this is by a wide margin the easiest route.

If that is not available, ask your GP — but go in knowing it is a long list. A GP may need to split it across two or three requests written over separate appointments to keep each one clinically defensible, and some will decline parts of it. That is a reasonable professional judgement, not an obstruction. Asking for a referral back to your oncologist is often the better move, and a good GP will write one on the spot.

Timing

Two practical points that change the quality of your results.

If you are still menstruating, book Day 0 bloods for day 2 to 4 of your cycle, in the early follicular phase. Hormone markers vary enormously across a cycle, and comparing a Day 0 taken mid- cycle against a Day 90 taken during your period tells you about the calendar rather than about you. Post-menopausal, any fasting morning works.

Then repeat under the same conditions. Same time of day, same fasting state, ideally the same laboratory — reference ranges and assay methods differ between labs, and a change of provider can look exactly like a change in you.

The one that is not a blood test

A DEXA bone density scan is the surveillance item most consistently recommended for this group and the one nobody thinks to ask for, because it is imaging rather than pathology and never appears on a blood form.

It matters if you are about to start weight-bearing exercise, because without a baseline you have no way of knowing whether it is doing anything. It is a low-dose X-ray at a radiology practice: you lie on an open table for about ten minutes, no injection, nothing enclosed, two sites measured, and you are given a T-score.

In Australia, bone densitometry is not automatically rebated. There are specific MBS items and the referral must state which clinical indication applies — commonly aromatase inhibitor therapy, premature or treatment-induced menopause, risk-reducing oophorectomy, prolonged corticosteroids, or a previous minimal-trauma fracture. If none applies you can still have the scan privately for a modest fee. Other countries fund it differently.

One thing makes DEXA different from everything else here: do not book a repeat at Day 90. Bone density cannot meaningfully change in ninety days, and the scan carries a precision error large enough that a short repeat would show you noise and let you read it as progress.

What you do with the numbers

Four draws — Day 0, 30, 60 and 90 — aligned to cell renewal cycles. The point is not any single result. It is the shape of the line, and the fact that the line belongs to something you chose to do.

Your doctor interprets your results. What the ninety days gives you is a before and an after for a change you made deliberately, which is something almost nobody leaves treatment with.