Cancer Diagnosis and Prognosis After Guillain–Barré Syndrome: A Population-Based Cohort Study

INTRODUCTION: It is unclear whether Guillain–Barré syndrome (GBS) can be a marker of a paraneoplastic syndrome. We examined whether GBS is associated with cancer and whether the prognosis of GBS patients with cancer differs from that of other cancer patients. MATERIALS AND METHODS: We conducted a population-based cohort study of patients diagnosed with GBS between 1978 and 2017 using Danish registry-data. Main outcome measures were cancer incidence and mortality after cancer diagnosis. We calculated absolute risks of a cancer diagnosis, treating death as competing risk, and standardized incidence ratios (SIRs) as measures of relative risk. We matched each GBS cancer patient with up to 10 cancer patients without a GBS diagnosis and examined the six-month survival after cancer diagnosis using Cox regression analysis. RESULTS: We identified 7897 patients (58% male, median age 57 years) with GBS. During a median follow-up of 9.5 years, the one-year risk of cancer was 2.7% (95% confidence interval (CI), 2.4–3.1). The SIR was increased throughout follow-up, but most noticeably during the first year after diagnosis (SIR: 3.35, 2.92–3.83). SIRs were particularly elevated for hematologic cancers (SIR: 8.67, 6.49–11.34), smoking-related cancers (SIR: 3.57, 2.81–4.47), and cancers of neurological origin (SIR: 8.60, 5.01–13.77). Lung cancer was the main contributor to the overall excess risk, which persisted after 36 months of follow-up (SIR: 1.17, 1.09–1.25). The mortality rate ratio comparing patients diagnosed with any cancer within one year of their GBS diagnosis and matched GBS-free cancer cohort members was 1.56 (95% CI, 1.27–1.90). CONCLUSION: GBS patients had a three-fold increased risk of cancer diagnosis in the first year of follow-up. The absolute cancer risk was almost 3.0%. A GBS diagnosis was an adverse prognostic marker for survival following cancer diagnosis. Clinicians should consider occult cancer in patients hospitalized with GBS.