Validation of Combs prognostic scoring system in Indian recurrent glioma patients treated with re-radiation

Retrospective audit of recurrent glioma patients treated by different fractionation schedules and to validate the modified Combs prognostic score in Indian patient cohort.

Between Jan 2009 and June 2022, 66 recurrent gliomas patients treated with standard adjuvant treatment-radiation (RT) ± temozolomide (chemotherapy)-and re-treated with RT (±chemotherapy) were categorized as per modified Combs prognostic criteria and outcomes were compared.

Sixty-six patients with recurrent gliomas who received reirradiation (re-RT) were audited-53% males; 61% Karnofsky performance status (KPS) ≥80 at time of re-RT; median age 41.5 years (range, 6 to 70 years); 67% <50 years; primary histology low-grade glioma in 33% ; grade III 27%, grade IV 40%; initial median dose of 60 Gy equivalent dose in 2 Gy fractions EQD2; maximum safe resection at recurrence 41%; mean and median follow-up 78 ± 51 months and 66 months. Mean time interval between RT was 46.4 ± 39 months. Mean planning target volume (PTV) volume in conventional RT (Conv-RT), hypofractionated RT (Hypo-RT), and ultra-hypofractionated RT (UF-RT) was 226.1 ± 140.7 mL, 162.8 ± 123.3 mL, and 143.3 ± 145.8 mL. Mean dose for Conv-RT, Hypo-RT, and UF-RT was 50 Gy (range, 40 to 60), 31 Gy (range, 20 to 40), and 20 Gy (range, 10 to 30). Mean overall survival (OS) in Conv-RT, Hypo-RT, and UF-RT cohort was 18.8 months (range, 2.4 to 76.8); 6.6 months (range, 2 to 17.4), and 13.9 months (range, 3 to 131.9). Median OS as per Combs criteria were 16.6 months (Group a), 24.6 months (Group b), 4.6 months (Group c), and 3 months (Group d). Significant survival benefit was with good KPS score (KPS >80 vs. <80; 20.46 vs. 5.25 months; p < 0.001), patients receiving salvage chemotherapy (20.46 vs. 6.96 months; p = 0.001), and patients received re-RT biological equivalent dose BED3 >80 Gy (16.62 vs. 5.48 months; p = 0.03). Median OS in our patient cohort and Combs cohort in Group a was 16.6 and 19.5 months; Group b was 24.6 and 11.3 months; Group c was 4.7 and 8.1 months, and Group d was 2 and 5.5 months, respectively. Six months survival in our patient cohort and Combs cohort in Groups a, b, c, d were 100%, 92%, 34%, 17% and 94%, 79%, 70%, 41%, respectively. Twelve months survival in our patient cohort and Combs cohort in Groups a, b, c, d were 88%, 74%, 22%, 0% and 88%, 47%, 22%, 7%, respectively.

Modified Combs prognostic factors predicts OS and is applicable in Indian subcontinent patient population.