Time, pattern, and outcome of medulloblastoma relapse and their association with tumour biology at diagnosis and therapy: a multicentre cohort study

Abstract

Background: Disease relapse occurs in around 30% of children with medulloblastoma, and is almost universally fatal. We aimed to establish whether the clinical and molecular characteristics of the disease at diagnosis are associated with the nature of relapse and subsequent disease course, and whether these associations could inform clinical management.

Methods: In this multicentre cohort study we comprehensively surveyed the clinical features of medulloblastoma relapse (time to relapse, pattern of relapse, time from relapse to death, and overall outcome) in centrally reviewed patients who relapsed following standard upfront therapies, from 16 UK Children's Cancer and Leukaemia Group institutions and four collaborating centres. We compared these relapse-associated features with clinical and molecular features at diagnosis, including established and recently described molecular features, prognostic factors, and treatment at diagnosis and relapse.

Findings: 247 patients (175 [71%] boys and 72 [29%] girls) with medulloblastoma relapse (median year of diagnosis 2000 [IQR 1995-2006]) were included in this study. 17 patients were later excluded from further analyses because they did not meet the age and treatment criteria for inclusion. Patients who received upfront craniospinal irradiation (irradiated group; 178 [72%] patients) had a more prolonged time to relapse compared with patients who did not receive upfront craniospinal irradiation (non-irradiated group; 52 [21%] patients; p<0·0001). In the non-irradiated group, craniospinal irradiation at relapse (hazard ratio [HR] 0·27, 95% CI 0·11-0·68) and desmoplastic/nodular histology (0·23, 0·07-0·77) were associated with prolonged time to death after relapse, MYC amplification was associated with a reduced overall survival (23·52, 4·85-114·05), and re-resection at relapse was associated with longer overall survival (0·17, 0·05-0·57). In the irradiated group, patients with MB_Group3 tumours relapsed significantly more quickly than did patients with MB_Group4 tumours (median 1·34 [0·99-1·89] years vs 2·04 [1·39-3·42 years; p=0·0043). Distant disease was prevalent in patients with MB_Group3 (23 [92%] of 25 patients) and MB_Group4 (56 [90%] of 62 patients) tumour relapses. Patients with distantly-relapsed MB_Group3 and MB_Group4 displayed both nodular and diffuse patterns of disease whereas isolated nodular relapses were rare in distantly-relapsed MB_SHH (1 [8%] of 12 distantly-relapsed MB_SHH were nodular alone compared with 26 [34%] of 77 distantly-relapsed MB_Group3 and MB_Group4). In MB_Group3 and MB_Group4, nodular disease was associated with a prolonged survival after relapse (HR 0·42, 0·21-0·81). Investigation of second-generation MB_Group3 and MB_Group4 molecular subtypes refined our understanding of heterogeneous relapse characteristics. Subtype VIII had prolonged time to relapse and subtype II had a rapid time from relapse to death. Subtypes II, III, and VIII developed a significantly higher incidence of distant disease at relapse whereas subtypes V and VII did not (equivalent rates to diagnosis).

Interpretation: This study suggests that the nature and outcome of medulloblastoma relapse are biology and therapy-dependent, providing translational opportunities for improved disease management through biology-directed disease surveillance, post-relapse prognostication, and risk-stratified selection of second-line treatment strategies.

Funding: Cancer Research UK, Action Medical Research, The Tom Grahame Trust, The JGW Patterson Foundation, Star for Harris, The Institute of Child Health - Newcastle University - Institute of Child Health High-Risk Childhood Brain Tumour Network (co-funded by The Brain Tumour Charity, Great Ormond Street Children's Charity, and Children with Cancer UK).

Figure 1

Time to relapse and survival after medulloblastoma relapse according to treatment received (A) Time to relapse according to whether CSI was delivered at diagnosis. (B) Time from relapse to death or last follow-up in patients who did not receive upfront CSI, according to whether CSI was delivered at relapse. Ten patients were removed from time from relapse to death analysis due to: death from other cause (n=1), alive with disease (n=5), or missing data (n=4). CSI=craniospinal irradiation.

Figure 2

Time to relapse and pattern of relapse according to molecular subgroup in the irradiated group (A) Time to relapse in the four consensus molecular subgroups in patients who received upfront CSI (irradiated group). (B) Schematic representing the patients with distant disease at diagnosis, emergent distant disease at relapse, and distant disease at relapse according to molecular subgroup. (C) Different patterns of relapsed disease according to molecular subgroup and relapse pattern. MB_SHH=19 patients, MB_Group3=25 patients, MB_Group4=58 patients. CSI=craniospinal irradiation. MB=medulloblastoma.

Figure 3

Assessment of relapse characteristics by second-generation MB_Group3 and MB_Group4 subtypes (A) Sankey plot of the relationship between consensus MB_Group3 and MB_Group4 and second-generation subtypes I–VIII. (B) Time to relapse according to second-generation MB_Group3 and MB_Group4 molecular subtype. (C) The different patterns of relapsed disease according to second-generation MB_Group3 and MB_Group4 molecular subtype. Subtype II=9 patients. Subtype III=8 patients. Subtype V=7 patients. Subtype VII=8 patients. Subtype VIII=22 patients. MB=medulloblastoma.