Comparison of ALK status between primary and corresponding lymph node metastatic tumors in lung cancer patients

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Anaplastic lymphoma kinase (ALK) is a promising therapeutic target in non-small cell lung cancer (NSCLC) with ALK translocations.
• ALK translocations occur in 3-5% of NSCLC patients, and ALK inhibitors show high response rates.
• Limited data exists on the concordance of ALK status between primary lung tumors and metastatic sites.

Purpose of the Study:

• To investigate the consistency of ALK translocation status between primary lung tumors and corresponding metastatic lymph node tumors.
• To determine if ALK status in primary tumors can reliably predict ALK status in metastases for NSCLC patients.

Main Methods:

• Analysis of paired primary and metastatic lymph node tumors from 78 NSCLC patients.
• Patients had not received tyrosine kinase inhibitor (TKI) therapy prior to tissue sampling.
• Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) were used to detect ALK translocations.

Main Results:

• All 45 patients with ALK translocation-positive primary tumors also showed translocations in their metastases.
• In 33 ALK-negative primary tumors, one patient (3%) had an ALK-positive metastasis.
• No significant difference in ALK status was observed between primary and metastatic lung tumors.

Conclusions:

• ALK translocation status is highly consistent between primary lung tumors and metastatic sites.
• Testing ALK status in primary tumors is adequate for planning targeted therapy (TKI) in advanced NSCLC.
• Detecting ALK status in metastatic specimens may be beneficial if both primary and metastatic tissues are available and negative for ALK.