Conversely, considering the low FABP1 positivity rate in colorectal adenocarcinomas (71%) and the even lower frequency in other gastrointestinal adenocarcinomas, a negative FABP1 staining of an adenocarcinoma in the lung cannot indicate a pulmonary origin (48), consistent with our findings that FABP1 can also be negative in lmCRC patients. Here, FABP1 is linked to adenocarcinoma.