Clinical characteristics and prognosis of paraneoplastic syndromes: a single-center cohort study in Northern China.

Purpose: To explore the clinical features, treatment, and prognosis of paraneoplastic neurological syndromes (PNS). Methods: In this retrospective cohort study, the records of 114 patients diagnosed with probable (n = 65) or definite (n = 49) PNS between July 2016 and October 2024 were analyzed. Short-term outcome was defined as the point decrease in modified Rankin Scale score from peak disease to discharge(Δmodified Rankin Scale). Long-term prognosis was determined by mortality at last follow-up. Prognostic factors were identified using logistic regression and Cox models. The impact of tumors and high-risk antibodies on survival were assessed by Kaplan-Meier curves. Results: Of the 114 patients, 65 (57.0%) were males. The median age was 63 years. Muscle weakness (53.5%) was most common, followed by seizures and altered consciousness. Associated tumors occurred in 66.7% of patients, mainly lung (65.8%) and breast cancer (9.2%). Antibodies were detected in 79.8%, including (single and multiple antibody types) anti-GABABR (24.2%), anti-Hu (19.8%), and anti-SOX1 (19.8%). Multiple antibodies were detected in 18.4%, including anti-Hu plus anti-SOX1 (19.0%), anti-SOX1 plus anti-GABABR (14.3%), and others. Independent factors associated with short-term favorable outcome (Δmodified Rankin Scale ≥1) were age < 65 years(OR = 3.41, 95% CI: 1.45-7.98, P = 0.005), CNS involvement (OR = 2.46, 95% CI: 1.05-5.80, P = 0.039), and immunotherapy (OR = 5.12, 95% CI: 1.70-15.42, P = 0.004). The median survival was 32 months (IQR, 12-106), the 3-year survival rate was 45.8%. SCLC (HR = 3.04, 95% CI: 1.71-5.41, P < 0.001) and high-risk antibodies (HR = 2.06, 95% CI: 1.17-3.62, P = 0.012) were independently associated with higher mortality. Conclusions: Age < 65 years, CNS involvement and immunotherapy are relevant to favorable short-term outcome. SCLC and high-risk antibodies are adverse factors of long-term survival in PNS.