Exploring resistance to initial chemotherapy in small cell lung cancer: The role of bone metastasis and other clinicopathologic characteristics.

Clinically, approximately 10% to 20% of small cell lung cancer (SCLC) patients do not respond well to initial platinum-based first-line chemotherapy. Knowledge about the clinicopathologic characteristics of these primary drug-resistant populations is limited. This study aimed to explore the clinicopathologic characteristics in SCLC populations insensitive to initial chemotherapy. This study enrolled SCLC patients with insensitivity to initial chemotherapy and analyzed their clinicopathological characteristics. Binary logistic regression analysis was used to determine the independent factors that influence chemosensitivity. The study evaluated 142 cases to determine the clinicopathologic characteristics of SCLC populations with insensitivity to initial chemotherapy. Between the chemotherapy-insensitive group (n = 32) and the chemotherapy-sensitive group (n = 110), no significant differences were observed in sex, age, smoking status, tumor size, lymph-node metastasis, vascular invasion, carcinomatous lymphangitis, mediastinal invasion, superior vena cava syndrome, tumor stage, brain metastases, pleural metastasis, lung metastasis, adrenal metastasis, or the immunohistochemical markers cytokeratin, synaptophysin, chromogranin A, thyroid transcription factor-1, and Ki-67 (all P > .05). However, significant differences in liver metastasis (P = .005), bone metastasis (P < .001), and neural cell adhesion molecule expression (P = .027) were identified. Binary logistic regression analysis revealed that bone metastasis (P = .008) was an independent high-risk factor for insensitivity to initial first-line chemotherapy. Bone metastasis is an independent high-risk factor for insensitivity to initial chemotherapy in SCLC. Enhancing our understanding of SCLC biology and osteoimmuno-oncology could identify new vulnerabilities and better define patient populations that may benefit from tailored clinical treatments to overcome drug resistance.