NTRK1 and colorectal cancer: Since TPM3-NTRK1 was first described in a human colorectal carcinoma [14], NTRK fusions have been detected in lung cancer [15], papillary thyroid carcinoma [16], colorectal cancer [17], sarcoma (including GIST) [8,9,10], and rare tumors such as secretory breast cancer [18] and mammary analog secretory carcinoma (MASC) [19].