Fine-needle aspiration (FNA) cytology demonstrated several advantages over traditional biopsies in diagnosing gastrointestinal stromal tumors (GISTs), including reduced time, improved sample representability, and superior diagnostic accuracy, according to findings published in Cancer Medicine.

Researchers in Sweden compared 2 methods, biopsy and FNA, and collected 460 tissue samples from 347 patients diagnosed with GISTs between 1999 and 2019. They collected 212 tissue samples via biopsy and 248 samples via FNA.

FNA cytology took an average of 4.5 days to reach a diagnosis compared with biopsies which took an average of 12.3 days. The authors attributed this reduction in time to diagnosis partially because of shorter preparation and processing times for FNA smears, and partially because of institutional variations in established routines and designated processing times within different laboratories.


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Samples obtained via FNA showed a significantly increased percentage of tumor cells (sample representability) compared to samples obtained using biopsy (92% vs 77%, respectively). The researchers suggested that superficial sampling from biopsies contributed to this finding due to the deeper, submucosal location of GISTs.

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FNA and core-needle biopsies demonstrated increased sample representation compared with mucosal sampling techniques because of the depth achieved during sample collection, the authors said. FNA cytology demonstrated improved diagnostic accuracy compared with biopsies (84% vs. 76%, respectively) and they attributed this superior diagnostic accuracy to the higher sample representability.

The researchers discovered that laboratory technicians could adequately perform additional diagnostic techniques such as molecular analysis and immunochemistry to determine the presence of KIT or PDGFRA gene variants using FNA samples.

They also revealed that lack of mitotic count presented a major drawback to FNA cytology—samples containing increased mitotic counts of 5mm2 are required for standard tumor growth risk assessments. In contrast, FNA cytology did allow for analysis of GIST mutational status to determine tumor sensitivity to the first-line neoadjuvant therapy, imatinib.

“FNA cytology is an accurate and time-efficient method for preoperative diagnosis of GISTs both as a complement to biopsies and as a stand-alone sampling method,” the authors concluded.

Reference

Zhang Y, Renberg S, Papakonstantinou A, Haglund de Flon F. Diagnosing gastrointestinal stromal tumors: the utility of fine-needle aspiration cytology versus biopsy. Cancer Med. Published online March 17, 2022. doi:10.1002/cam4.4630