Visit preparation

Lung cancer progresses after EGFR-targeted therapy. Do I still need a biopsy if my T790M blood test is negative?

If lung cancer progresses after treatment with a first- or second-generation EGFR-targeted drug and a plasma test does not detect T790M, doctors in China may still recommend testing a tissue sample. The report means the test did not detect the variant in that blood sample. The next step depends on whether there is a suitable site that can be sampled safely.

SinoCareHub Content Team·November 9, 2026·2 min

Check when the test was done and which sample was used

EGFR stands for epidermal growth factor receptor. The EGFR gene is relevant to treatment in some cases of non-small cell lung cancer. T790M is a resistance variant that can emerge after first- or second-generation EGFR-targeted therapy. At your follow-up visit, read the report’s sample type and test result together. A plasma test looks for tumour DNA that has entered the bloodstream. A result of ‘not detected’ on this test alone cannot rule out T790M in the tumour tissue. In this situation, the Chinese Medical Association’s lung cancer guideline recommends testing tissue when feasible.[1]

Why look at a lesion that has progressed?

A paraffin block kept from your initial diagnosis can help the doctor check the original pathology and molecular test results. If a lesion that has recently progressed can be sampled safely, its tissue can also show whether the tumour’s pathological type has changed and help the team assess how it may have become resistant to treatment. The team decides whether and where to sample based on the scans, the location of the lesion and the risks of the procedure. Where the cancer has progressed and how extensive that progression is will affect what the team discusses.[1,2]

Prepare a timeline before a follow-up visit in China

Put the initial pathology report, the original genetic test report, the generic names and start and stop dates of each targeted drug you have taken, the latest plasma test report and the original scans from before and after progression in date order. Ask the thoracic oncology team, “Is T790M what we need to check again this time? What can the samples we already have tell us? If a new sample is needed, which lesion would be the most suitable?” If you need to borrow pathology slides, first ask the receiving pathology department what materials it needs, then follow the guide to borrowing pathology slides between hospitals in China. This article covers the specific situation after first- or second-generation drugs. If the cancer progresses after a third-generation drug, the treating team needs to assess it using the appropriate clinical pathway.[1,2]