# 21A
EVALUATION OF A MULTIPARAMETRIC SYSTEM ABLE TO PREDICT NON-SENTINEL LYMPH NODE STATUS IN BREAST CANCER PATIENTS
WITH A MICROMETASTATIC SENTINEL NODE ASSESSED BY THE ONE STEP NUCLEIC ACID AMPLIFICATION (OSNA) ASSAY
Simonetta Buglioni, Marcella Mottolese, Beatrice Casini, Enzo Gallo, Irene Terrenato, Edoardo Pescarmona, Simona Di Filippo, Ferdinando Marandino, Gianluigi Ferretti, Franco Di Filippo
Regina Elena Cancer Institute, Rome, Italy
ABSTRACT
Background: Axillary lymph node dissection (ALND) may not be necessary in women with breast cancer (BC) who have micrometastasis in a
sentinel lymph node (SLN), owing to the low risk of non-SLN (NSLN) involvement. In our Institute we validated and adopted the molecular
diagnostic tool OSNA based on the quantitative measurement of Cytokeratin 19 (CK19) mRNA. The aims of our work in a subgroup of women
with micrometastatic SLN, were: 1) to correlate the copy numbers of CK19 mRNA with the risk of additional positive NSLNs; 2) to assess the
relationships between the molecular subtype classification and the probability of a positive ALND; 3) to verify whether a combination of the
new above mentioned parameters is able to identify a subgroup of patients with a micrometastatic SLN and a negligible risk of positive NSLNs
in whom ALND may be avoided. Methods: The SLN lysates from 709 patients were analyzed by OSNA assay. We considered only patients
with a micrometastatic SLN (copy numbers between 250 and 5000/μL) and the probability of having a positive ALND was calculated by the
logistic regression model. This series of BC patients were divided into four main subtypes taking in account the BC classification as defined by
a combination of estrogen, progesteron receptors and HER2 status. Results: OSNA positivity for micrometastasis was reported in 91/709
cases (12,8%).The number of patients with positive ALND was 20 (22%). The statistical analyses showed that the metastatic involvement of
NSLNs is associated with SLNs with a high copy numbers (>2000) of CK19 mRNA together with HER2 subtype. Otherwise none of the luminal
A patients with a positive SLN but presenting a copy number <1000, had a positive NSLNs. Conclusions: We showed that biologically-driven
analyses may be able to build new models with higher performance in terms of breast cancer axillary status prediction after positive SLN
biopsy for micrometastasis. The copy numbers of CK19 mRNA and the molecular subtypes are more advantageous than traditional parameters
because
they
are
not
pathologist-dependent
and
therefore
they
are
more
reliable
and
reproducible.
AIMS
Characteristics
Luminal A
Luminal B
HER2
Triple Negative
Total cases
63
7
15
6
91
Biomarker distribution
ER
+
+
-/+
Neg
PgR
+
+
-/+
Neg
HER2
Neg
Neg
Pos
Neg
Ki67
Low
High
Low/High
High
56
7
5
2
6
9
4
2
Total 91
%
709
55 (26-83)
Histotype
Intraductal Carcinoma
62
8.7
Invasive Ductal Carcinoma
596
84.1
Invasive Lobular Carcinoma
438
6.0
8
1.2
G1
56
7.9
G2
505
71.2
G3
148
20.9
Tis
62
8.7
T1a
80
11.3
T1b
122
17.2
T1c
293
41.3
T2
152
21.5
516
72.8
N1m
91
12.8
N1
84
11.9
N2
14
2.0
N3
4
0.5
Other
Grading
Lymph node status
N. Of cases
N0
%
Histotype
Invasive Ductal Carcinoma
83
91.2
Invasive Lobular Carcinoma
8
8.8
G1
21
23.1
>5000 copies mRNA/µL
G2
48
52.7
G3
22
24.2
(+) micrometastasis
250 – 5000 copies mRNA/µL
T1a
14
15.4
<250 copies mRNA/µL
T1b
11
12.1
T1c
40
43.9
T2
26
28.6
OSNA copy
number
Subtype
ALND
results
280-1000
1300-3200
300-540
3000-3600
630-1700
2500-3200
270-830
1000-1700
LA
LA
LB
LB
HS
HS
TN
TN
Negative
Positive
Negative
Positive
Negative
Positive
Negative
Positive
The number of patients with positive ALND was 20 (22%). Our findings showed that the
metastatic involvement of NSLNs is associated with SLNs with a high copy numbers
(>1000) of CK19 mRNA together with HER2 subtype. Otherwise none of the luminal A
patients with a positive SLN but presenting a copy number <1000, had a positive NSLNs
B
A
Gradig
Table 3. Subtype distribution in 91 BC patients with a micrometastic SLN
N.
of cases
Median age (range)
Table 2. Pathological characteristcs of the
91 BC patients with a micrometastatic SLN
Table 4. Detailed analysis of the 91 micrometastatic cases
Breast Cancer
Subtype
Number of patients
METHODS
(++) macrometastasis
OSNA
results
+
+
+
+
+
+
+
+
N. of cases
Tumor size
RESULTS
SLNs
Characteristics
In our series of 709 BC patients we focused on the 91 cases with
micrometastatic SLN concomitantly detected by OSNA and
immunohistochemistry , aimed to:
 correlate the copy numbers of CK19 mRNA with the risk of
additional positive NSLNs;
 assess the relationships between the molecular subtype
classification and the probability of a positive ALND;
 identify a subgroup of patients with a micrometastatic SLN and
a negligible risk of positive NSLNs in whom ALND may be
avoided.
The OSNA test measures the
amount of CK19 mRNA (the
number of copies) that is
correlated with the number of
CK19
positive
cells
and
therefore the size of the
metastases
(-) negative/ITC
Table 1. Clinico-pathological characteristcs of the 709
breast cancer patients
Tumor size
Micromestastasis in SLN
detected using both CK19
immunohistochemistry fig. A
and OSNA assay fig. B
Table 5. Logistic regression analysis in 709 BC patients
Probalility of a positive ALND
OR
95% CI
Subtypes
LA vs LB
LA vs HS
LA vs TN
Grading
G1+G2 vs G3
T
T1 vs T2
OSNA Assay
+ vs ++
P-value
1.16
2.82
1.56
0.45-3.01
1.33-6.00
0.46-5.28
0.755
0.007
0.476
1.66
0.82-3.89
0.162
1.52
0.81-2.85
0.191
4.76
2.47-9.19
<0.0001
BC subtypes, tumor grading, tumor size and copy number of CK19 mRNA
were studied by logistic regression analysis. As summarized in this table
the model indicates that the probability to find an ALND positive is
significantly higher in patients with HER2 positive tumors and with SLN
OSNA ++
CONCLUSIONS
In conclusion results obtained in our series of 91 micrometastatic
cases showed that:
Biologically-driven analyses may be able to build new models with
higher performance in terms of breast cancer axillary status
prediction.
The copy numbers of CK19 mRNA and the molecular subtypes are
more advantageous than traditional parameters because they
provided quantitative and objective results which are more reliable
and reproducible.
ASCO Annual Meeting 2012 Chigago, Illinois June 1-5, 2012