A recent study indicated that the diagnostic sensitivity of RET fusion-positive lung cancer using the FISH technique was 100% (85.8%–100%), and the specificity was 85% (62.1–96.8%), although the specificity may be underestimated given that the study set the positivity cutoff to be ≥10% tumor cells, demonstrating a RET rearrangement pattern (14). Here, RET is linked to neoplasm.