Proton therapy re-irradiation provides promising clinical results in recurrent brain meningioma

Figures & data

Table 1. Patient baseline clinical and treatment characteristics.

Characteristics	No.
No. of patients	32
Median age at re-irradiation (IQR)	61 (16)
Gender
Female	19 (59%)
Male	13 (41%)
Median KPS (range)	90 (60–90)
Tumor location
Skull base	21 (65%)
Convexity	6 (18%)
Falcine/parasagittal	5 (17%)
Initial pathologic grade (WHO)
Grade 1	16 (50%)
Grade 2	13 (40%)
Grade 3	3 (10%)
Deficits before re-irradiation
Pain	6 (18%)
Headache	10 (48%)
Cranial nerve deficit	23 (72%)
Dizziness	3 (10%)
Seizures	4 (12%)
Surgery before re-irradiation	21 (65%)
Adjuvant re-irradiation	11 (52%)
Re-irradiation at relapse	10 (48%)
Pathologic grade at time of re-irradiation
Grade 1	10 (32%)
Grade 2	16 (50%)
Grade 3	6 (18%)
Total no. of prior courses of radiotherapy
1	29 (90%)
2	3 (10%)
Prior radiotherapy modality
SRS 1-fraction (median dose 13.5 Gy; range 11.6–22.5 Gy)	12 (37.5%)
Mf-SRS 3–5 fractions (median dose 19 Gy; range 18–25.6 Gy)	10 (31.5%)
EBRT 25–30 fractions (median dose 54 Gy; range 50–60 Gy)	8 (25%)
PT 30 fractions (60 GyRBE)	2 (6%)
Time from prior radiotherapy to re-irradiation, mo (range)	66 months (range 4–288 months)
Prior radiotherapy dose in EQD2 brain, Gy (range)	53.7 Gy (range 30−137.8 Gy)
Prior radiotherapy dose in EQD2 tumor, Gy (range)	44.3 Gy (range 26.7−99.4 Gy)
Total EQD2 brain, Gy (range)	104.5 Gy (range 53.8−198.4 Gy)
Total EQD2 tumor, Gy (range)	98 Gy (range 78.9−159.4 Gy)
Median GTV at re-irradiation (range), cm^3	43 cm^3 (range 1.2−225.5 cm^3)

KPS: Karnofsky Performance Status; SRS: radiosurgery; Mf-SRS: multi-fraction radiosurgery; EBRT: external beam radiation therapy; PT: proton therapy; EQD2 brain: biologic equivalent dose at 2 Gy for brain, assuming a/b of 2 for brain tissue; EQD2 tumor: biologic equivalent dose at 2 Gy for tumor, assuming a/b of 4 for meningioma; GTV: gross tumor volume.

Figure 1. Progression-free survival analysis.

Figure 2. Overall survival analysis.

Table 2. Acute and late treatment-related toxicity.

	Acute toxicity (%)		Late toxicity (%)
Side effect	Grade 1 and 2 Grade 3 and 4 (%)		Grade 1 and 2 Grade 3 and 4 (%)
Fatigue	65	0	50	0
Erythema	40	3	0	0
Alopecia	37	0	22	0
Headache	31	0	12.5	0
Nausea	12.5	0	0	0
Vomiting	6	0	0	0
Radionecrosis	3	0	6	6
Hydrocephalus	0	3	0	0
Conjunctivitis	22	0	3	0
Seizure	6	6	9	6
Dizziness	9	0	0	0
Pain	12.5	0	6	0
Otitis	12.5	0	6	0

Data availability statement

The data that support the findings of this study are available on request from the corresponding author [DS]. The data are not publicly available due to ethical restriction.