2019 ASM / R-0115
Outcomes following radiotherapy for brain metastases in patients with primary breast cancer – an Australian population-based study
Keywords:
CNS, MR, Radiation therapy / Oncology, Cancer
Authors:
W. L. Ong, T. M. J. Kang, M. Wada, J. Ruben, S. Senthi, J. Millar, F. Foroudi; VIC/AU
DOI:
10.26044/ranzcr2019/R-0115
Results
SRS utilisation
- A total of 336 women with primary BC who had radiotherapy for BM were included in this study, of which 27% (92/336) were treated with SRS technique (Table-1)
- The mean age at first course of brain radiotherapy was 59 years old (SD=12.6)
- A total of 533 courses of brain radiotherapy were delivered, of which 37% (195/533) were classified as SRS
- Two-thirds of SRS were delivered in public institutions (127/195), compared to one-third (68/195) in private institutions (P<0.001)
- Almost all SRS were delivered in metropolitan centres (94%) compared to regional centres (6%) (P<0.001)
- There was no significant change in trend in SRS use from 2013 to 2016 (P-trend=0.9)
- In multivariate logistic regression, treatment in regional centres was the only factors independently associated with lower likelihood of SRS use (OR=0.35; 95%CI=0.17-0.75; P=0.007)
Table-1 | Baseline characteristics of women with primary breast cancer who received radiotherapy for brain metastases
|
non-SRS
(n=244)
|
SRS
(n=92)
|
P-value |
Age at radiotherapy for BM, year |
|
|
|
<50 |
50 (63%) |
29 (37%) |
0.2 |
50-59 |
74 (73%) |
28 (27%) |
|
60-69 |
73 (77%) |
22 (23%) |
|
≥70 |
47 (78%) |
13 (22%) |
|
Socioeconomic status |
|
|
|
1st quintile (most disadvantaged) |
44 (76%) |
14 (24%) |
0.1 |
2nd quintile |
46 (78%) |
16 (25%) |
|
3rd quintile |
48 (78%) |
16 (25%) |
|
4th quintile |
52 (78%) |
15 (22%) |
|
5th quintile (least disadvantaged) |
54 (61%) |
34 (38%) |
|
Remoteness of area of residence |
|
|
|
Major city |
175 (74%) |
63 (26%) |
0.6 |
Regional/ remote |
69 (70%) |
92 (27%) |
|
Treatment institution type |
|
|
|
Public |
131 970%) |
55 (30%) |
0.3 |
Private |
113 (75%) |
37 (25%) |
|
Treatment institution location |
|
|
|
Metropolitan |
186 (69%) |
83 (31%) |
0.004 |
Regional |
58 (87%) |
9 (13%) |
|
Year of first BM radiotherapy |
|
|
|
2013 |
40 (74%) |
14 (26%) |
0.9 |
2014 |
71 (74%) |
25 (26%) |
|
2015 |
79 (72%) |
30 (28%) |
|
2016 |
54 (70%) |
23 (30%) |
|
Overall survival
- The median follow-up was 4.5 months (IQR=1.9-9.8)
- There were 267 deaths observed at a median of 4.1 months post-radiotherapy (IQR=1.6-8.3)
- The 6-month and 12-month OS in all women were 47% and 26% respectively
- The 6-month and 12-month OS in women who had SRS were 70% and 44% respectively, compared to 38% and 20% in women who did not receive SRS (P<0.001; Figure-1)
- In multivariate Cox regression, SRS use was associated with improved OS (HR=0.48; 95%CI=0.35-0.65; P<0.001), while patients age >70 had worse OS compared to those aged