BACKGROUND: The Oncomine Dx Target Test (ODxTT) is a next-generation 
sequencing-based companion diagnostic test which has been recently developed; 
however, its analysis success rate could be improved, especially for small 
samples. The aim of this study was to identify the pathological factors 
associated with biopsy specimens that affect the analysis success rate of ODxTT.
METHODS: We retrospectively investigated 119 cases subjected to ODxTT at 
Kanagawa Cancer Center. Data pertaining to the results of BRAF V600E mutation 
analysis in ODxTT and pathological factors based on microscope slides were 
collected. Pathological factors including tissue surface area, tumor cell count, 
and tumor content rate were assessed. We constructed receiver operating 
characteristic curves and determined the optimal cutoff values of each 
pathological factor. Multivariate logistic analysis was used to identify 
significant factors.
RESULTS: A total of 98 of 119 samples were successfully analyzed (75.6%). The 
tissue surface area and tumor cell count were significantly higher in the group 
associated with analysis success (P < 0.001 and P = 0.011, respectively), and 
their optimal cutoff values were 1.04 mm2 and 375 cells, respectively. A tissue 
surface area > 1.04 mm2 and tumor cell count >375 cells had a positive effect on 
the analysis success rate of ODxTT (odds ratio [OR] 0.10; 95% confidence 
interval [CI]: 0.03-0.35; P < 0.001 and OR 0.25; 95% CI: 0.07-0.90; P = 0.033, 
respectively).
CONCLUSIONS: Selecting samples with a tissue surface area > 1.04 mm2 and a tumor 
cell count >375 cells might improve the analysis success rate of ODxTT.
KEY POINTS: Significant findings of the study: We found that a tissue surface 
area > 1.04 mm2 and tumor cell count >375 cells had a positive effect on the 
analysis success rate of ODxTT in the analysis of biopsy tissue samples.
WHAT THIS STUDY ADDS: It is sometimes necessary to assess genetic alterations 
with a small biopsy sample in daily practice. The criteria mentioned above will 
help to determine which tests should be performed, ODxTT or multiple single-gene 
testing.