Purpose: The risk of developing metastatic squamous cell carcinoma for patients with head and neck squamous cell carcinoma (HNSCC) is very high. Because these patients are often heavy tobacco users, they are also at risk for developing a second primary cancer, with squamous cell carcinoma of the lung (LSCC) being the most common.The distinction between a lung metastasis and a primary LSCC is currently based on certain clinical and histologic criteria, although the accuracy of this approach remains in question. Experimental Design: Gene expression patterns derived from 28 patients with HNSCC or LSCC from a single center were analyzed using penalized discriminant analysis. Validation was done on previously published data for 134 total subjects from four independent Affymetrix data sets. Results: We identified a panel of 10 genes (CXCL13, COL6A2, SFTPB, KRT14, TSPYL5, TMP3, KLK10, MMP1, GAS1, and MYH2) that accurately distinguished these two tumor types. This 10-gene classifier was validated on 122 subjects derived from four independent data sets and an average accuracy of 96% was shown. Gene expression values were validated by quantitative reverse transcription-PCR derived on 12 independent samples (seven HNSCC and five LSCC). The 10-gene classifier was also used to determine the site of origin of12 lung lesions from patients with prior HNSCC.
Conclusions:The results suggest that penalized discriminant analysis using these 10 genes will be highly accurate in determining the origin of squamous cell carcinomas in the lungs of patients with previous head and neck malignancies.Patients with head and neck squamous cell carcinoma (HNSCC) are at high risk for the development of metastatic carcinoma in the lung. Studies suggest that 5% to 15% of patients with HNSCC develop lung metastases (1). However, because patients with HNSCC are often heavy tobacco users, they are also at risk for second primary cancers, with squamous cell carcinoma of the lung (LSCC) being the most common (2).In some cases, the distinction between a lung metastasis and a second primary lung carcinoma can be easily distinguished on clinical grounds. The presence of multiple pulmonary nodules is usually considered evidence of metastatic disease. However, in subjects who present with a solitary lung nodule, the distinction between metastasis and primary carcinoma can be more problematic. Usually, patients with HNSCC who are found to have solitary pulmonary lesions undergo surgery or needle biopsy with pathologic evaluation. If the lung lesion is also of squamous cell histology, the distinction between metastasis and primary LSCC is extremely difficult. Currently, this distinction is made by comparison of histologic grade or by the presence of other premalignant changes in the respiratory epithelium; however, the accuracy of this approach is unclear.Making the correct diagnosis has practical importance for choice of therapy. Although patients with either a primary LSCC or a solitary HNSCC metastases may be eligible for surgical resection, the c...