Vol 66, No 3 (2016)
Research paper (original)
Published online: 2016-07-12

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Comparative evaluation of tolerability and efficacy of four schedules of post-operative radiotherapy in patients with glioblastoma multiforme

Grzegorz Głowacki
Nowotwory. Journal of Oncology 2016;66(3):193-201.

Abstract

Background. The results of GBM patients’ treatment are poor and prognosis is unfavourable. Nowadays the primary treatment consists of radical surgery and adjuvant radiochemotherapy. There are a great number of prognostic factors for survival and in some cases, due to poor condition of the patient or an extension of the tumour, a palliative or symptomatic treatment remains the only approach. Stereotactic radiotherapy could be an option in palliative treatment, although it role in GBM patients is still not well defined. Probably in some patients, an increase of total dose with the use of a stereotactic boost may be a potential treatment option worth consideration.

Aim. The aim of the study was to provide a specification of the overall survival prognostic factors and evaluation of the efficacy and tolerance of four schedules of radiotherapy.

Material. The analysed group consisted of 227 GBM patients aged from 20 to 80 (132 men, 95 women). Depending on the performance status and extension of the surgery all patients were qualified for one of four radiotherapy schedules.

Methods. A Kaplan-Meier actuarial calculation and log-rank test were performed to evaluate the overall survival. The differences between groups were considered to be statistically significant if the p-value was less than 0.05. The Cox proportional hazard regression model was used to define independent prognostic factors of survival. Results. Univariate analysis showed that performance status (p = 0.0001), neurological condition (p = 0.00002), age (p = 0.005), tumour volume (p = 0.004), tumour stage (p = 0.02), neurosurgery (p = 0.01), treatment schedule (p = 0.00001) and salvage treatment (p = 0.0001) significantly influenced the overall survival. Neurological condition was highly correlated with performance status (p = 0.0001). The multivariative Cox regression model revealed that the following variables independently influenced overall survival: performance status, neurosurgery, preoperative tumour volume, multifocal disease, salvage treatment (mainly radiosurgery). The toxicity of radiotherapy was low and in general well tolerated.

Conclusions.

— Age below 40 years, good performance status (Zubrod 0–2), single tumour, volume of the tumour (up to 30 cm3) and cytoreductive surgery are statistically significant and independent positive prognostic factors of overall survival.

— The additional radiosurgical boost as a component of primary palliative treatment or as a secondary treatment at patients with good performance status and small residual tumours allows prolongation of the overall survival in comparison to the groups of patients with other salvage (but without SRS) or without any salvage therapy.

— The tolerance of treatment is good and acceptable and comparable in all radiotherapy schedules used.