Resection extent and BRAF V600E mutation status determine postoperative tumor growth velocity in pediatric low-grade glioma: results from a single-center cohort analysis.

PURPOSE

Despite excellent long-term overall survival rates, pediatric low-grade gliomas (pLGG) show high variety of clinical behavior regarding progress or senescence post incomplete resection (IR). This study retrospectively analyzes tumor growth velocity (TGV) of pLGG before surgery and after IR to investigate the impact of surgical extent, tumor location and molecular BRAF status on postoperative residual tumor growth behavior.

METHODS

Of a total of 172 patients with pLGG receiving surgical treatment, 107 underwent IR (66%). Fifty-three vs 94 patients could be included in the pre- and post-operative cohort, respectively, and were observed over a mean follow-up time of 40.2 vs 60.1 months. Sequential three-dimensional MRI-based tumor volumetry of a total of 407 MRI scans was performed to calculate pre- and postoperative TGV.

RESULTS

Mean preoperative TGV of 0.264 cm/month showed significant deceleration of tumor growth to 0.085 cm/month, 0.024 cm/month and -0.016 cm/month after 1st, 2nd, and 3rd IR, respectively (p < 0.001). Results remained significant after excluding patients undergoing (neo)adjuvant treatment. Resection extent showed correlation with postoperative reduction of TGV (R = 0.97, p < 0.001). ROC analysis identified a residual cut-off tumor volume > 2.03 cm associated with a higher risk of progress post IR (sensitivity 78,6%, specificity 76.3%, AUC 0.88). Postoperative TGV of BRAF V600E-mutant LGG was significantly higher than of BRAF wild-type LGG (0.123 cm/month vs. 0.016 cm/month, p = 0.047).

CONCLUSION

This data suggests that extensive surgical resection may impact pediatric LGG growth kinetics post incomplete resection by inducing a significant deceleration of tumor growth. BRAF-V600E mutation may be a risk factor for higher postoperative TGV.