Safety Tests Before — Your First Chemotherapy Dose

A routine blood test measures what is in your blood right now — your counts, your organ function. A pharmacogenomic test looks at your inherited genetic code to predict how your body will process a specific drug. The variants it looks for were present at birth and will not change over time. They are relevant only for certain chemotherapy drugs, which is why not every patient needs one.

The most established tests are the DPYD test, used before fluoropyrimidine-based regimens; the TPMT and NUDT15 tests, used before thiopurine drugs given mainly for blood cancers; and the UGT1A1 test, used before irinotecan-containing regimens. Whether any of these applies to you depends entirely on which drugs your oncologist is planning. Ask specifically about the drugs in your regimen and whether a genetic test exists for them.

These tests are available at select molecular diagnostic laboratories in India, particularly in larger cities. They are not yet part of routine oncology protocols, and most cancer centres do not order them as standard. If you want to know whether testing is available for your specific regimen, ask your oncologist. Availability varies, and your centre or a referral lab may be able to arrange it.

That decision belongs to your oncologist, based on your specific variant, your overall health, and what alternatives exist for your cancer type. Finding a variant does not necessarily mean you cannot have the drug. It means your team has information to plan with. Do not adjust anything on the basis of a result without discussing it with your oncologist first.

Awareness of these tests is still growing across oncology practice in India. Some are not covered by insurance. And the CPIC and ESMO-PGx guidelines that recommend pre-treatment genetic testing for certain drugs have not yet been adopted uniformly across Indian cancer centres. The absence of testing reflects where routine practice currently stands — it is not indifference to your safety, and raising it with your team is entirely reasonable.

Yes, it is a reasonable question — particularly if your planned regimen includes drugs for which CPIC or ESMO-PGx guidelines recommend pre-treatment testing. Your oncologist can tell you whether a test applies to your specific drugs and whether it is available at your centre. Raising this is not a challenge to your oncologist's judgment. It is participation in your own care.

The routine workup — blood counts, organ function, heart assessment — is standard and always ordered before treatment begins. It is not optional. Pharmacogenomic tests are not currently required as standard in Indian oncology protocols. They are recommended by international guidelines for specific drugs and available at some centres, but whether to order one is a clinical decision your oncologist makes based on your regimen.

The routine tests — blood counts and organ function in particular — are repeated regularly throughout treatment, because chemotherapy affects these values and your team adjusts your care accordingly. Pharmacogenomic tests do not need to be repeated. Your inherited genetic variants do not change, so once the result is known it applies for any future treatment involving the same drug class.