Insulinoma-associated protein 1 is a novel diagnostic marker of small cell lung cancer in bronchial brushing and cell block cytology from pleural effusions: Validity and reliability with cutoff value.

INSM1 is a novel diagnostic marker for SCLC, and is useful in both bronchial brushing and pleural effusion cytology specimens. Because INSM1 generally is expressed in <10% of tumor cells in adenocarcinomas, determining an accurate cutoff value for INSM1 is important in the diagnosis of SCLC.