511P Immunodisruptive conditions and glioma diagnosis: 24-year retrospective study of an under-recognized scenario

Disruption of the immune system is known to favor carcinogenesis and cancer breakthrough. Gliomas constitute de most prevalent primary malignant brain tumors. We aimed to study the occurrence of immune disruptive conditions (IDC) in patients with gliomas at our institution. Retrospective study of patients (pts) diagnosed with a glioma at Hospital Clínico Universitario San Carlos, Madrid (Spain). IDCs included autoimmune diseases (AID), organ transplantation (OT) requiring chronic immunosuppressive therapy (IST), and hematological malignancies (HM). A descriptive study, as well as time since IDC, time under IST, and progression-free survival (PFS) and overall survival (OS) since glioma diagnosis were analyzed. Within the period January 1999 – April 2023, among 481 patients diagnosed with a glioma, 30 (6.2%) patients harbored IDCs. Male/Female: 14/16. Age: 63y (32-83). WHO 5th Ed.: IDH-WT GB: n=26 (MGMTmeth: 50%, MGMTunmeth: 50%), IDH-MUT Astro: n=3, Pleomorphic xanthoastro: n=1. Frontal: n=14, Temporal: n=8, Parietal: n=6. Unilobar: n=23, Bilobar: n=4, Trilobar: n=1. Right: n=8, Left: n=19, Bilateral: n=3. Resection: GTR=8, STR=1, Partial=3, Biopsy=14. RTx=20 pts, CRTx=18, Adj CTx=13. Median PFS and OS since diax were 9 and 10 months (m), respectively. No. of IDCs: 1 (n=21 pts), ≥ 2 (n=9 pts). IDC type: AID (n=27 pts) among which: endocrine (4: Addison, Hypothyroidism, Hashimoto's thyroiditis), respiratory (7: asthma, sarcoidosis, alergic rinoconjunctivitis), cutaneous (7: chronic eccema, psoriasis), neurological (4: multiple sclerosis, Guillain-Barré), digestive system (2: inflammatory bowel disease), rheumatological (13: Horton's disease, Sjöegren's syndrome, systemic lupus erithematosus, uveitis, vasculitis); HM (1: chronic lymphocytic leukaemia); OT (2: renal). IST for IDCs used in 20 pts (systemic IST in 17). Median time since IDC: 101 m (10-411). Median time under IST: 108 m (0-283). Within a large 24-year long retrospective series, a minority of pts with glioma harbored an IDC, most commonly rheumatological, respiratory, or cutaneous. Studies should be conducted to unveil if gliomas occurring in pts with IDCs are biologically and immunologically distinct.