Performing VATS to obtain more tissue or initiating chemotherapy while waiting for results from the current biopsy in this patient is counter-intuitive. Because EGFR status in primary and metastatic tumors may not be identical, however, EGFR status in the primary tumor may not predict EGFR status in metastases or sites of disease recurrence.

ALK gene rearrangements are currently detectable using IHC, FISH, or reverse-transcriptase polymerase chain reaction, also known as RT-PCR. In the United States, as of June 2013, the only FDA-approved test for detection of ALK rearrangements is the FISH test.

Molecular testing on resected stage I-III lung cancer specimens allows for enrollment in clinical trials that target mutation-specific, directed therapy and assists with therapy selection for recurrent disease when it occurs. Resected surgical specimens are the gold standard against which small volume histology or cytology specimens are measured for adequacy, both for histologic diagnosis of cancer and molecular testing. Resected tissue may be available, however, in only that subset of patients with NSCLC who undergo surgical resection with curative intent.

While the most recent available tissue is preferred for molecular analysis there is no strong evidence to justify procedures solely to procure tissue from a metastasis prior to initiation of TKI therapy if an earlier primary lesion is available and suitable for analysis, unless there is strong suspicion of its origin from a separate primary.

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References:

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