A rational diagnostic algorithm for the identification of ALK rearrangement in lung cancer: a comprehensive study of surgically treated Japanese patients

PLoS One. 2013 Aug 1;8(8):e69794. doi: 10.1371/journal.pone.0069794. Print 2013.

Abstract

Background: EML4-ALK fusion gene is found in only a small subset (2-6%) of non-small cell lung cancer. There is an urgent need to establish a rational diagnostic algorithm to identify this rare but important fusion in lung cancer.

Methods: We performed a comprehensive analysis of EGFR/KRAS mutation and ALK rearrangement in a total of 360 surgically resected lung cancers. ALK rearrangement was examined by 3 analyses: multiplex reverse transcription-PCR, fluorescent in situ hybridization (FISH), and immunohistochemistry (IHC) with the intercalated antibody-enhanced polymer method. A scoring system was used for IHC (iScore). A test set (202 patients with unselected lung cancer) was used for proposing a diagnostic algorithm. This diagnostic algorithm was validated in 158 patients with EGFR and KRAS mutation-negative adenocarcinoma.

Results: ALK rearrangement was identified in 2 patients (1.0%) from the test set and both adenocarcinomas were negative for EGFR and KRAS mutations. The results of FISH and RT-PCR were completely matched. The highest iScore 3 was found only in the 2 positive cases. A diagnostic algorithm was proposed: IHC screening for ALK rearrangement followed by confirmatory FISH. In the validation set, 8 cases (5.1%) had iScore 3 and were positive for FISH, while the other cases had iScore 0 and were negative for FISH.

Conclusions: Screening for ALK rearrangement by IHC followed by confirmatory FISH is a rational diagnostic algorithm. If needed, patients may be selected for screening ALK rearrangement by their EGFR and KRAS mutation status.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Algorithms*
  • Anaplastic Lymphoma Kinase
  • Asian People*
  • DNA Mutational Analysis / methods*
  • Female
  • Gene Rearrangement*
  • Humans
  • Lung Neoplasms / genetics*
  • Lung Neoplasms / pathology
  • Lung Neoplasms / surgery*
  • Male
  • Receptor Protein-Tyrosine Kinases / genetics*
  • Sensitivity and Specificity

Substances

  • ALK protein, human
  • Anaplastic Lymphoma Kinase
  • Receptor Protein-Tyrosine Kinases

Grants and funding

This work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Health, Labor and Welfare of Japan (10103778, and by the Smoking Research Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding received for this study.