2009 Background: Radiotherapy (RT) plus concomitant and adjuvant temozolomide (TMZ) is now the standard of care for newly diagnosed glioblastoma. The occurrence of pseudo-progression at the end of RT is an often-mentioned phenomenon, but the actual incidence is unknown. It is also unclear if this is only a radiological phenomenon or is accompanied by clinical signs and symptoms. We retrospectively assessed this phenomenon in a cohort of patients treated with chemo-irradiation with temozolomide (RT/TMZ). Methods: The pre- and post-chemo-radiotherapy brain CT’s and MRI’s from all patients treated with RT/TMZ for a malignant glioma in the Daniel den Hoed Cancer Center between 2000 and 2005 were reviewed. Treatment consisted of 60 Gy RT in 6 weeks combined with daily TMZ (75mg/m2/day), followed after 4 weeks by 6 cycles of TMZ (150–200 mg/m2/day 1–5 every 4 weeks). Scans were made prior to the start of RT, four weeks after the end of RT and thereafter every three months. Macdonald’s criteria were used to assess the response. In addition information was collected on clinical signs and symptoms, dexamethasone dose, histology, and survival. Results: Sixty-five patients were identified; 54 had been diagnosed with a GBM. Mean age was 48 years and 42 were male. In 23 patients the first follow-up scan 4 weeks after the end of RT showed progression as compared to the pre-RT imaging. This was accompanied by clinical deterioration in12 patients. All patients continued with adjuvant TMZ. In 12 of these 23 patients the MRI and clinical signs and symptoms stabilized or improved in the months thereafter. In 8 of these 12 patients a response was observed without additional treatment other than TMZ. In none of these cases changes in dexamethasone dose could explain the observed MRI changes. Conclusions: In up to 50% of high grade glioma patients treated with chemo-irradiation with TMZ and a progressive MRI lesion immediately after RT suffer from pseudo-progression; this was observed in 12 out of 65 patients. These data support the notion to continue TMZ in case of progressive lesions immediately after RT/TMZ. Studies on recurrent gliomas that accept patients with progressive lesions directly after chemo-radiation will lead to an overestimation of the results. No significant financial relationships to disclose.
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Taal et al. (2007) studied this question.