Ideas, guides and answers from Oncquest Laboratories

Yes. Expression may differ between tumour areas, between a primary and metastatic site, or after treatment. Whether a newer sample or repeat test would be useful is a clinical decision based on tissue availability and the treatment question.[6]

Not universally. Whether a PD-L1-negative result excludes a therapy depends on the medicine, tumour type, disease setting, assay and jurisdiction. Some regimens do not require PD-L1 positivity, while others do. Check the current applicable label or guideline; do not generalize from another cancer.[10]

Often the laboratory can use stored tissue from an earlier biopsy or operation. Another procedure may be considered if that tissue is unavailable, inadequate or no longer suitable for the clinical question. Your doctor should explain whether a new biopsy could add useful information and what risks it carries.