TISSUE BIOPSY AND PATHOLOGICAL DIAGNOSIS IN SCLC

Abstract

Lung cancer remains the most common cancer type and the leading cause of cancer mortality globally, and Small Cell Lung Cancer (SCLC) constitutes 13-15% of all such cases (Rudin et al., 2021). SCLC is an undifferentiated epithelial tumor ith neuroendocrine features that grows rapidly, metastasizes early, and has a poor prognosis. Although patients respond to chemotherapy at initial diagnoses, many patients relapse, and the five-year survival rate is below 7% (Keog et al., 2022). Being an aggressive form of cancer, there is a need to ensure that the illness is diagnosed early and accurately in order to provide corresponding treatment. An accurate pathological diagnosis is crucial for achieving an initial differentiation between SCLC and Non-Small Cell Lung Cancer (NSCLC) and determining the subsequent management. Chromogranin A, synaptophysin, and CD 56 are Immunohistochemistry (IHC) markers for recognizing SCLC with neuroendocrine features. However, these markers are not specific enough; thus, newer markers that include INSMA-associated protein 1 (INSM1) and Delta-like protein 3 (DLL3) are more specific for diagnosis and have the potential for targeted therapy. Despite restricted availability, tissue biopsy remains the most definitive method for SCLC diagnosis. However, other advanced tools such as EBUS-TBNA and CT-guided percutaneous needle biopsy are also used in today's practice. However, in more recent molecular categorization, SCLC has been further distinguished from NSCLC by other specific molecular markers that can be targeted for therapy. Immunohistochemistry, biopsies, and molecular markers can improve the identification of SCLC and assist with tailored therapy.