Abstract 959P
Background
To identify whether there is an association of gross tumor volume (GTV) and brain metastasis (BM) development in patients with stage III non-small cell lung cancer (NSCLC). Other potential risk factors were also investigated.
Methods
Retrospective multicenter study (4 Dutch, 1 Italian center). Included: patients with stage III NSCLC (staged with FDG-PET and brain MRI), treated with radical chemoradiotherapy (CRT). Excluded: participation in interventional clinical trial, other malignancy ≤5 years of NSCLC diagnosis; CRT after surgery. The time to BM was calculated from the date of pathological diagnosis to the date of imaging confirmed BM or last follow-up if no event was observed. Competing risk analysis was performed to identify risk factors for BM, in which death without BM was treated as competing event. Factors that were significant in the univariate analysis were included in the multivariate analysis.
Results
In total, 327 out of 506 patients were eligible, among which 55% were male. The median GTV was 71.06 cm3 (range: 4.9 – 1252.9). The median follow-up was 52.7 months (95% CI: 43.2-62.3), during which 193 (59%) patients died and 51 (15.6%) developed BM (84.3% symptomatic). The median overall survival was 30.8 months (95% CI: 24.1-37.5). Univariate analysis showed that females were at higher risk of developing BM (HR=2.02, 95% CI: 1.16-3.53, p=0.01); higher age (HR=0.94, 95% CI: 0.92-0.97, p<0.001) and squamous cell carcinoma (SCC) (HR=0.31, 95% CI:0.15-0.65, p=0.0017) were associated with a lower risk. GTV (HR=1.00, 95% CI=0.999-1.00, p=0.42) and other factors (Table) were insignificant (p>0.05). Multivariate analysis showed that higher age (HR=0.96, 95% CI: 0.93-0.98, p=0.002) and SCC (HR=0.42, 95% CI: 0.19-0.92, p=0.03) were independent protective factors for developing BM. Table: 959P
Clinical features and risk of BM
No./median (range) (N=327) | Univariate | Multivariate | |||
HR (95% CI) | p** | HR (95% CI) | p | ||
Age | 67 (35-88) | 0.94 (0.92-0.97) | <0.001 | 0.96 (0.93-0.98) | 0.002 |
Gender | |||||
M* | 180 | - | |||
F | 147 | 2.02 (1.16-3.53) | 0.01 | 1.34 (0.75-2.40) | 0.32 |
Smoker | |||||
Former/never* | 182 | ||||
Current | 140 | ||||
BMI | 25.1 (15.6-45.3) | ||||
Underweight | 15 | ||||
Normal* | 129 | ||||
Overweight | 105 | ||||
Obesity | 47 | ||||
NA | 31 | ||||
PS | |||||
0* | 126 | ||||
1 | 171 | ||||
2 | 23 | ||||
3 | 4 | ||||
NA | 3 | ||||
Pathology | |||||
SCC | 126 | 0.31 (0.15 -0.65) | 0.002 | 0.42 (0.19-0.92) | 0.03 |
NSCC* | 201 | - | |||
T | |||||
0-3* | 180 | ||||
4 | 147 | ||||
N | |||||
0 | 36 | ||||
1 | 16 | ||||
2* | 205 | ||||
3 | 70 | ||||
Stage | |||||
IIIa* | 177 | ||||
IIIb | 150 | ||||
GTV | 71.1 (4.3 – 1252.9) | ||||
Total RT dose | 61.2 (14-74) | ||||
SER | 56 (10-141) | ||||
RT duration | 39 (4-66) | ||||
Timing of RT | 15 (-73 ∼ 111) | ||||
CRT | |||||
CCRT* | 294 | ||||
SCRT | 33 | ||||
RT type | |||||
ODRT* | 207 | ||||
TDRT/mix | 120 |
∗: reference ∗∗ reported if p<0.05
Conclusions
GTV was not significantly associated with the development of BM in patients with stage III NSCLC. Patients with non-squamous pathology and younger age were at higher risk to develop BM.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
MAASTRO.
Funding
Scholarship of China Scholarship Council (Grant No. : CSC 201909370087).
Disclosure
All authors have declared no conflicts of interest.