Background: To compare survival and hematological toxicity rates between two postoperative therapy regimens in patients with primary glioblastoma (GBM), namely temozolomide (TMZ) concomitant to radiation, followed by adjuvant TMZ, versus adjuvant TMZ after radiation only.
Patients and methods: A total of 191 patients with primary GBM were postoperatively treated with either radiation and concomitant TMZ, followed by adjuvant TMZ (Stupp protocol) (n = 154), or radiation followed by adjuvant TMZ (n = 37). The incidence of hematological adverse effects (AE) was recorded for all patients. From both treatment groups, 26 patients were matched according to age, Karnofsky performance scale (KPS) score, and O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation.
Results: Hematological AEs were mild in both unmatched groups, but were significantly more frequent in the concomitant plus adjuvant TMZ group (p < 0.001). Matched-pair analysis confirmed significantly more frequent hematological AEs in the concomitant and adjuvant group compared to the sequential (adjuvant) TMZ group (p = 0,012). Patients treated with concomitant plus adjuvant TMZ showed significantly longer progression-free survival (PFS) (10.6 versus 6.6 months; p = 0.014), but no prolonged overall survival (OS) (16.9 vs. 15.6 months; p = 0.717) compared to patients who received the sequential treatment regimen.
Conclusion: In this retrospective study, the OS in patients with primary GBM treated with sequential TMZ following radiation appeared to be similar to that in patients treated with concomitant plus adjuvant TMZ. Given the significantly higher risk of hematological AE for concomitant treatment, the role of concomitant plus adjuvant TMZ use compared to sequential administration of TMZ, especially for patients with MGMT-unmethylated tumors, should be further evaluated.