Toxicities Associated with Continuing Disease-Modifying Antirheumatic Drugs for Collagen Vascular Diseases During Head and Neck Intensity-Modulated Radiotherapy: A Single-Institution Experience.

ImportanceLimited evidence exists to guide the safe use of radiotherapy (RT) and concurrent disease-modifying antirheumatic drugs (DMARDs) in patients with collagen vascular disease (CVD).ObjectiveTo describe toxicity outcomes in patients with CVD receiving intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC) and to evaluate whether concurrent DMARD use is associated with increased toxicity.DesignRetrospective cohort study.SettingSingle academic tertiary care center in the United States, from 2005 to 2022.ParticipantsTwenty-three adult patients with CVD [eg, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), dermatomyositis (DM)] and biopsy-proven HNC treated with curative-intent IMRT. Eligibility required available treatment records and ≥90 days of follow-up post-RT.Intervention or ExposuresDefinitive or postoperative IMRT for HNC. Exposure of interest was concurrent use of DMARDs during RT.Main Outcome MeasuresRates of acute (≤90 days) and late (>90 days) grade ≥2 and ≥3 toxicities, as graded by CTCAE v5.0. Fisher exact tests were used to compare toxicity rates by DMARD use.ResultsMedian follow-up was 56 months (IQR 9-98). Most common CVDs were RA (39%), SLE (17%), and DM (17%). Median RT dose was 66 Gy (range 48-70 Gy); 39% received concurrent chemotherapy. Acute grade ≥3 toxicity occurred in 35% (n = 8) and late grade ≥3 in 13% (n = 3). No grade ≥4 toxicities were observed. DMARD use during RT was not associated with higher rates of acute or late grade ≥2 or ≥3 toxicity (P > .1 for all comparisons).ConclusionsIMRT was associated with moderate rates of severe toxicity in patients with CVD, but DMARD use during RT did not increase risk.RelevanceConcurrent DMARDs may be safely continued during IMRT for HNC in patients with CVD. Prospective studies are needed to confirm these findings and refine risk stratification by CVD subtype and treatment regimen.