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Gregory J. Riely, MD, PhD


Are NTRK Fusions Found in Both Secretory and Nonsecretory Breast Cancers?

By: Kayci Reyer
Posted: Monday, March 21, 2022

According to research presented in Pathology International, NTRK fusions may be present in both secretory and nonsecretory breast cancer tumor subtypes. Findings from previous studies suggested that NTRK fusions may be restricted to the secretory tumor subtype alone.

“The variety of NTRK genes and fusion partners identified in both subtypes suggests that [next-generation sequencing]‐based NTRK fusion testing should be considered for all breast cancers to identify [patients] who may benefit from [tyrosine receptor kinase] inhibitors, following confirmation by [tyrosine receptor kinase immunohistochemistry],” concluded Jeffrey S. Ross, MD, of Upstate Medical University, Syracuse, New York, and colleagues.

Within a large, real-world, next-generation sequencing data set, the study identified 23 NTRK fusion–positive cases that had hematoxylin and eosin stain imaging available. This imaging helped to determine the secretory status of the selected tumors. Across 23 cases, 11 tumors were secretory, 11 were nonsecretory, and 1 was mixed status. Among nonsecretory tumors, 70% contained TP53 mutations, and seven cases harbored NTRK1 fusions. Each of the seven cases had a different fusion partner. In the secretory group, seven cases contained ETV6-NTRK3 fusions. Patients with secretory tumors tended to be younger, to have a lower tumor mutational burden, and to have estrogen receptor–negative disease, although the authors noted that these findings were not statistically significant.

Disclosure: For full disclosures of the study authors, visit

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