A Case of Primary Lung Adenocarcinoma With Metastasis to Colon Harboring EGFR Exon 19 Deletion

Lung cancer metastasizing to the colon is exceedingly rare and can present similarly to colorectal cancer. It is crucial to conduct further evaluations using immunohistochemical (IHC) stains and genomic testing to differentiate between the two and provide appropriate treatment without delay. Lung cancer generally has a poor prognosis, especially in cases with distant metastases. Although gastrointestinal (GI) metastases from lung cancer have been reported, cases of lung cancer manifesting as colon metastasis are extremely rare, with only a few instances documented.