High mutational concordance between primary colorectal tumors and associated pulmonary metastases.

Background and Objectives Precision medicine has altered the management of colorectal cancer (CRC). However, the concordance of mutational findings between primary CRC tumors and associated pulmonary metastases (PM) is not well-described. This study aims to determine the concordance of genomic profiles between primary CRC and PM. Methods Patients treated for colorectal PM at a single institution from 2000 to 2017 were identified. Mutational concordance was defined as either both wild-type or both mutant alleles in lung and colorectal lesion; genes with opposing mutational profiles were reported as discordant. Results Thirty-eight patients met inclusion criteria, among whom KRAS, BRAF, NRAS, MET, RET, and PIK3CA were examined for concordance. High concordance was demonstrated among all evaluated genes, ranging from 86% (KRAS) to 100% concordance (NRAS, RET, and MET). De novo KRAS mutations were detected in the PM of 4 from 35 (11%) patients, 3 of whom had previously received anti-epidermal growth factor receptor (EGFR) therapy. Evaluation of Cohen's kappa statistic demonstrated moderate to perfect correlation among evaluated genes. Conclusions Because high intertumoral genomic homogeneity exists, it may be reasonable to use primary CRC mutational profiles to guide prognostication and targeted therapy for PM. However, the possibility of de novo KRAS-mutant PM should be considered, particularly among patients previously treated with anti-EGFR therapy.