Cancer Risk in a Large Inception SLE Cohort: Effects of Age, Smoking, and Medications

Abstract

Background/Purpose: Many studies of cancer risk in SLE are limited by small sample size or use of administrative data, which rely on billing code diagnoses instead of clinical data. No studies to date focused on incident SLE. We studied cancer risk in the largest-ever cohort of clinically confirmed incident SLE patients.

Methods: Patients meeting ACR criteria for new-onset SLE (within 15 months of diagnosis) were enrolled into the SLICC Inception Cohort, across 32 centres. Patients are followed yearly using a standard protocol, with detailed data collection including SLE Disease Activity Index-2000 (SLEDAI-2K) and damage, and drugs in the past year. New cancer diagnoses are recorded by the examining physician at the annual study visit, and confirmed with chart review including pathology reports.

Multivariate proportional hazard regression was performed, using baseline variables for demographics (age at SLE onset, sex, race/ethnicity), and time-dependent variables for drugs (corticosteroids, anti-malarial drugs, immunosuppressive drugs), smoking, and SLEDAI-2K. As well as cancer over-all, we evaluated risk factors for the most common cancer types.

Results: Of 1848 new-onset SLE patients enrolled between 1999-2011, 1668 had at least one follow-up; these were the sample for the current analysis. End date was the first of death, last visit, or end of study interval for this analysis (Aug. 2015). Baseline demographics are shown in Table 1.