Validation of the prognostic Heidelberg re-irradiation score in an independent mono-institutional patient cohort

Purpose: Re-irradiation has been shown to be a valid option with
proven efficacy for recurrent high-grade glioma patients. Overall,
up to now it is unclear which patients might be optimal candidates
for a second course of irradiation. A recently reported prognostic
score developed by Combs et al. may guide treatment decisions and
thus, our mono-institutional cohort served as validation set to
test its relevance for clinical practice. Patients and methods: The
prognostic score is built upon histology, age (< 50 vs. >= 50
years) and the time between initial radiotherapy and re-irradiation
( 12 months). This score was initially introduced
to distinguish patients with excellent (0 points), good (1 point),
moderate (2 points) and poor (3-4 points) post-recurrence survival
(PRS) after re-irradiation. Median prescribed radiation dose during
re-treatment of recurrent malignant glioma was 36 Gy in 2 Gy single
fractions. A substantial part of the patients was additionally
treated with bevacizumab (10 mg/kg intravenously at d1 and d15
during re-irradiation). Results: 88 patients (initially 61 WHO IV,
20 WHO III, 7 WHO II) re-irradiated in a single institution were
retrospectively analyzed. Median follow-up was 30 months and median
PRS of the entire patient cohort 7 months. Seventy-one patients
(80.7%) received bevacizumab. PRS was significantly increased in
patients receiving bevacizumab (8 vs. 6 months, p = 0.027, log-rank
test). KPS, age, MGMT methylation status, sex, WHO grade and the
Heidelberg score showed no statistically significant influence on
neither PR-PFS nor PRS. Conclusion: In our cohort which was mainly
treated with bevacizumab the usefulness of the Heidelberg score
could not be confirmed probably due to treatment heterogeneity; it
can be speculated that larger multicentric data collections are
needed to derive a more reliable score.