P17.46LATE PSEUDOPROGRESSION IN GLIOBLASTOMA PATIENTS: COMPARABLE ANALYSIS WITH REAL TUMOR PROGRESSION

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2014-09, Vol.16 (Suppl 2), p.ii98-ii98
• Main Authors: Kamer, S., Akagunduz, O., Ertan, Y., Akalın, T., Özgiray, E., Oner, K., Eraslan, C., Çallı, C., Oktar, N., Anacak, Y.
• Format: Article
• Language: English
• Subjects: Poster Presentations
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/nou174.375

PURPOSE: Pseudoprogression is defined among the glioblastoma (GBM) patients as clinical deterioration and/or radiological enlargement and contrast enhancement after radiochemotherapy which resolves during the follow-up. It is typically detected within 3 months after radiochemotherapy. Late pseudoprogression is not common and not clearly defined yet. We analyzed 33 patients who were reoperated for clinical/radiological progression after chemoradiotherapy and compared the clinicopathologic characteristics of the patients without any histologic evidence of tumor with those having real tumor progression. MATERIAL AND METHODS: We identified histologically verified GBM patients who underwent a second tumor resection after radiochemotherapy due to clinical deterioration and/ or radiologically progression between January 2010- October 2013. All pathological specimens were evaluated in our center and were separated in two groups; GroupA: real recurrence of GBM, Group B:late pseudo progression, either no evidence of tumor, complete necrosis or treatment related changes reminding tumor regression. We determined survival after primary surgery and re-resection with regard to pathological results using Kaplan-Meier estimates. RESULTS: 33 patients were included in this study. Median age was 51 (range:17-72), male/female ratio was 2.3/1. After the radiochemotherapy, clinical deterioration and/ or radiologically progression was detected median 10 months later (range: 4-22months).After the secondary surgery, 18 patients (55%) showed late pseudoprogression but 15 patients (45%) experienced real tumor recurrence in the pathological evaluation. From the diagnosis, 2-year survival rate was 26.3% in whole group. 2-year survival rate was 36% in patients who had late pseudoprogression and 16.7% in patients who had real tumor progression (p:0,45). After the secondary surgery, 2 year survival rate was 11% in cases with late pseudoprogression and median survival was 9 months (range:4-28 months). In patients who experienced real tumor recurrence, 2-year survival after secondary surgery was%0 and median survival was 4 months (range: 2-12 months) . Median time to recurrence was 9 months (range :5-22 months) in patients with late pseudoprogression but 11 months (range:4-18 months) in patients experienced real tumor recurrence. CONCLUSION: GBM patients occasionally undergone reoperation due to clinical deterioration or radiological progression, however no evidence of tumor is found in som