Pathologists' staging of multiple foci of lung cancer: poor concordance in absence of dramatic histologic or molecular differences.

OBJECTIVES: A long-standing problem in lung cancer pathology has been to determine whether two anatomically distinct foci of lung carcinoma are independent primaries or intrapulmonary metastases. While several proposals exist with respect to this problem, it is not known how pathologists use these proposals in actual practice.
METHODS: We performed a voluntary survey of the Pulmonary Pathology Society, a self-selected group of pathologists with a specialty interest in pulmonary pathology, to determine their opinion on staging various specific scenarios of multiple foci of lung cancer.
RESULTS: We found that there was a great deal of disagreement and uncertainty in the approach to these scenarios unless there were also unambiguous molecular markers or a dramatic difference in histology.
CONCLUSIONS: Pathologists have a high degree of uncertainty and disagreement on staging multiple lung carcinomas. An improved pathologic method is required to distinguish separate primary tumors from intrapulmonary metastases. Until that is available, improved nomenclature is needed to convey the intrinsic uncertainty of the situation. Copyright© by the American Society for Clinical Pathology.