Should You Ask for — Pharmacogenomic Testing?

Yes. Asking is not overstepping. Many oncologists do not routinely offer it — partly because it applies only to certain drugs, partly because availability and awareness vary, and partly because it adds a step to treatment planning. Raising it yourself opens the conversation. Your oncologist will tell you whether it is relevant to the drugs in your plan, whether it can be arranged, and whether the timeline allows for it. That conversation cannot happen if you do not ask.

The clearest evidence sits with fluoropyrimidines — a class that includes 5-FU and capecitabine — where a gene called DPYD governs how quickly the drug is processed. Irinotecan and thiopurines are also covered by CPIC and DPWG clinical guidance, involving different genes. Whether any of these apply to you depends on your specific treatment plan. Ask your oncologist which drugs are in your regimen and whether a pharmacogenomic test is relevant for any of them.

Carrying a variant does not mean chemotherapy cannot go ahead. It means your oncologist has information they need to plan your treatment with that fact taken into account. What happens next is a clinical decision that belongs to your treating team — and that is exactly why the testing decision should be made with them, not independently of them. The value of knowing in advance is that your team can plan. Not knowing only removes that option.

If there is time before the first cycle, it is worth raising the question now. Even a few days can be enough, depending on the laboratory. If your treatment needs to start immediately, your oncologist will weigh that urgency against the delay a test would require — that is their call to make, not yours to resolve alone. The most useful thing you can do is ask today, so your team has the information in time to act on it.

There is no fixed national price, and costs vary between laboratories and cities. Any figure you find online may be out of date or specific to one lab. Ask directly at your treatment centre: some include relevant tests in pre-treatment bloodwork, and others will refer you to a specialist laboratory with its own pricing. Cost is worth knowing before you decide, and your team can usually point you to a realistic range for your situation.

They are completely different tests. Tumour biomarker testing — PD-L1, MSI, EGFR and similar — looks at the cancer's own DNA to identify which treatments it is likely to respond to. Pharmacogenomic testing looks at your inherited DNA to check whether your body can safely process certain drugs. One is about whether the cancer will respond; the other is about whether you will tolerate the drug. They require different samples, answer different questions, and neither replaces the other.

Ask your oncologist whether a referral to a specialist genetics laboratory is possible — the test requires only a blood sample and does not have to be done at your treatment centre. If it cannot be arranged in time, ask what monitoring will be in place during your first cycle and what symptoms should prompt you to call immediately. The absence of a test does not mean nothing can be done; it means your team manages risk with the information they have.

No. Pharmacogenomic testing covers a specific set of inherited variations that affect how your body processes certain drugs. Most chemotherapy side effects — nausea, hair loss, fatigue, infection risk — are not predicted by this test and are not related to pharmacogenomic variants. It is one safety check for one category of risk, not a comprehensive screen for everything you might experience. Your oncologist will explain the expected side effects of your specific regimen separately.