PAX9 and lung carcinoma: On one hand, PAX8 acts primarily as a diagnostic marker to differentiate lung cancers from metastases originating in PAX8-positive tissues (e.g., thyroid, renal, ovarian cancers); on the other hand, PAX9 demonstrates a more direct role in lung cancer progression, particularly in lung adenocarcinoma (LUAD) and small cell lung cancer (SCLC), where it may help in prognostic determination.