Prognostic impact of paraneoplastic syndromes in patients with small cell lung cancer, real-world data.

Abstract

e20082 Background: Small cell lung cancer (SCLC) remains an aggressive cancer, with a reported mOS of 15-20 mo when localized (L-SCLC) and 9-11 mo when extensive (E-SCLC). Paraneoplastic syndromes (PNS) are a debilitating condition either related to the embryogenic stem cell origin or to auto-immune antibodies produced against the tumor. These mechanisms may be even more relevant with the use of immunotherapy for first-line treatment of E-SCLC. Methods: We retrospectively reviewed our clinical database of patients diagnosed with SCLC between 2006 and 2017 at CHUM University Center. The primary outcome was to compare OS of patients with and without PNS in L-SCLC and E-SCLC. No patients received immunotherapy. Results: We identified 426 unselected SCLC patients, 39% L-SCLC and 61% E-SCLC. 84 patients (20%) were diagnosed with a PNS: 66 (15%) SIADH, 8 (2%) paraneoplastic Cushing syndromes, 2 (1%) humoral hypercalcemia and 8 (2%) paraneoplastic neurologic syndromes. 25% of patients with PNS vs 14% without PNS had a PS 3-4 and would not have been eligible to a clinical trial. 65% of patients with PNS received chemotherapy vs 63% without PNS. Neurologic PNS were all diagnosed in patients with L-SCLC. PNS affecting the central nervous system (4 limbic encephalitis and 1 cerebellar degeneration) were associated with a poorer prognosis than L-SCLC without PNS (mOS 3,5 mo vs 16,7 mo (p = 0,003)). The 2 patients with Lambert-Eaton myasthenic syndrome had a long survival (29 and 82 mo), but persistence of the neurologic symptoms. 86% of patients with paraneoplastic Cushing syndrome were diagnosed with an E-SCLC and had a worse prognosis than E-SCLC without PNS (mOS 1,1 mo vs 4,63 mo (p = 0,022)). SIADH had a significative poor impact on OS in patients with L-SCLC (mOS 10,1 mo vs 16,7 mo (p = 0,016)), but no impact in survival for patients with E-SCLC (mOS 3,63 mo vs 4,63 mo (p = 0,735)). Conclusions: PNS either in patients with L-SCLC or E-SCLC worsen the overall prognosis, except for Lambert-Eaton myasthenic syndrome. A more systematic detection of these syndromes is suggested before starting immunotherapy as first-line standard treatment for E-SCLC. Furthermore, this real-world unselected clinical cohort shows our E-SCLC patients have a worse prognosis than the clinical trial experience.