Background
Methods
Ethics statement
Collection of blood samples and characteristics of recruited patient cohort
Characteristic | No. of patients | % |
---|---|---|
All patients |
45
|
100 %
|
Time between primary surgery and CTC sampling (DFI) | ||
≤ 5 years |
16
|
36 %
|
> 5 years |
21
|
47 %
|
Primary not removed |
8
|
18 %
|
Age at CTC sampling | ||
≤ 50 years |
4
|
9 %
|
> 50 years |
41
|
91 %
|
Menopausal status | ||
Premenopausal |
2
|
4 %
|
Postmenopausal |
43
|
96 %
|
Histologic grade (Bloom-Richardson) | ||
I, well differentiated |
5
|
11 %
|
II, moderately differentiated |
23
|
51 %
|
III, poorly differentiated |
4
|
9 %
|
Unknown |
13
|
29 %
|
Pathological tumor size | ||
pT1, ≤2 cm |
20
|
44 %
|
pT2-4, >2 cm |
22
|
49 %
|
Unknown |
3
|
7 %
|
Lymph nodes involved | ||
No |
14
|
31 %
|
Yes |
27
|
60 %
|
Unknown |
4
|
9 %
|
ERa statusa
| ||
Negative |
1
|
2 %
|
Positive |
44
|
98 %
|
PgR statusa
| ||
Negative |
5
|
11 %
|
Positive |
36
|
80 %
|
Unknown |
4
|
9 %
|
HER2/neu statusa
| ||
Negative |
37
|
82 %
|
Positive |
3
|
7 %
|
Unknown |
5
|
11 %
|
Histological type | ||
Lobular |
13
|
29 %
|
Ductal |
28
|
62 %
|
Ductolobular |
3
|
7 %
|
Ductal, signet-cell |
1
|
2 %
|
Adjuvant chemotherapy | ||
No |
31
|
69 %
|
Yes |
14
|
31 %
|
Adjuvant hormonal therapy | ||
No |
24
|
53 %
|
Yes |
21
|
47 %
|
Any adjuvant therapy | ||
No |
22
|
49 %
|
Yes |
23
|
51 %
|
Site of metastasis | ||
Visceral |
5
|
11 %
|
Non-visceral |
26
|
58 %
|
Both |
14
|
31 %
|
1st line treatment | ||
Anastrozol |
15
|
33 %
|
Letrozol |
16
|
36 %
|
Exemestane |
14
|
31 %
|
Median progression-free survival (PFS in days; range)b
| 358 (14–1255) | |
Median baseline CTC count (range in 7.5 mL blood) | 8 (0–32,492) |
Enumeration of CTCs
mRNA isolation from CTCs, qRT-PCR and quantification of gene transcripts
Reference genes, data normalization, and quality control
Statistical analysis
Results
Patient characteristics
8-gene CTC profile predicts for outcome to treatment
Gene |
P-value | t-value |
---|---|---|
TWIST1 | 0,001 | −2,879 |
KRT81 | 0,018 | −2,453 |
PTRF | 0,029 | −2,024 |
EEF1A2 | 0,031 | −1,895 |
PTPRK | 0,049 | −1,793 |
EGFR | 0,065 | −1,701 |
CXCL14 | 0,080 | 2,229 |
ERBB3 | 0,096 | 2,26 |
8-gene CTC profile | |||
---|---|---|---|
PFS <9 months | Favorable | Unfavorable | Total |
No | 22 | 4 | 26 |
Yes | 7 | 12 | 19 |
Total | 29 | 16 | 45 |
Pearson’s X
2 statistic | 10,93 | ||
P
| <0.001 |
Factor of base model | Univariate analysis | Multivariate analysis | ||||
---|---|---|---|---|---|---|
PFS | PFS | |||||
HR | 95 % CI |
P
| HR | 95 % CI |
P
| |
<5 vs. ≥5 CTCs at baseline | 1,11 | 0.57–2.15 | 0,753 | 1,31 | 0.65–2.62 | 0.455 |
Disease-free intervala
| 1,09 | 0.74–1.61 | 0,653 | 0,95 | 0.62–1.43 | 0.790 |
Dominant site of relapseb
| 1,34 | 0.69–2.58 | 0,384 | 1,11 | 0.56–2.18 | 0.768 |
8-gene CTC profile | 4,40 | 2.17–8.92 | <0.001 | 4,59 | 2.16–9.75 | <0.001 |
Hierarchical clustering to identify clusters of patients according to the 8-gene CTC predictor
Testing the 8-gene CTC profile in an independent differently treated patient cohort
8-gene CTC profile | |||
---|---|---|---|
PFS <9 months | Favorable | Unfavorable | Total |
No | 16 | 19 | 35 |
Yes | 17 | 19 | 36 |
Total | 33 | 38 | 71 |
Pearson’s X
2 statistic | 0,016 | ||
P
| 0.899 |