Paola Sala1, Maria Grazia Tibiletti2, Ileana Carnevali2,Stefano Signoroni1, Anna Maria Chiaravalli2, AlessandraStefano Signoroni1, Anna Maria Chiaravalli2, AlessandraViel3, Paolo Radice1, Massimo Milione1, Maria LuisaCarcangiu1, Valeria Pensotti,

Lucio Bertario1 and Alberto Morabito4

1 Fondazione IRCCS Istituto Nazionale Tumori,Milano

2 Ospedale di Circolo di Varese

3 CRO – Aviano

4 Università Studi Milano

5 Cogent

BACKGROUND

Background : Several strategies

have been developed to diagnose

Lynch Syndrome (LS). These

considered clinical criteria,

prediction modes, tumor testing,

germline testing. Particularly

Immunohistochemstry (IHC) tumorImmunohistochemstry (IHC) tumor

testing, for the evidence of lack of

expression of Mismatch Repair

(MMR) gene product is considered

an important diagnostic tool taken

in account by the most of

guidelines on the management of

LS.

STUDY DESING

� AIMS : To evaluate the effectiveness of a selective screening of CRC

patients by MMR IHC through the pooled experience of two center with

alike selection criteria

� Method : A retrospective analysis of MMR (MLH1, MSH2, MSH6, PMS2)

IHC genes expression testing in CRC of patients suspected for LSIHC genes expression testing in CRC of patients suspected for LS

(Amsterdam Criteria, Bethesda Guidelines) was carried out in two

centers (Unit of Hereditary Digestive Tumors - INT , Milan and Department

of Pathology –Varese Hospital). The focus of the analysis was to

evaluate the effectiveness for the identification of MMR genes carriers

among CRC patients and the presence of a germline mutation was

considered the gold standard. Performance characteristics (i.e. sensitivity,

specificity, positive and negative predictive values of MMR IHC for LS

identification) were evaluated with respect to the presence of germline

MMR gene mutation.

TESTS INT

n. 478

VARESE

n. 809

TOT

n. 1283

SEX: M/F 1.7

AGE MEAN (yrs.) 54 (+/- 14) 59 (+/-16) 55 (+/- 15)

AC I/II 189 (39%) 77 (9%) 248 (19%)

CRC site Prox. 171 (21%) 415 (51%) 586 (45.6%)

MSI 444 (93%) 590 (73%) 1034 (81%)

Defec. MMR IHC 124 (26%) 284 (35%) 426 (33%)Defec. MMR IHC

(OR 0.64)

124 (26%) 284 (35%) 426 (33%)

MSI H (OR 0.47) 114 ( 26%) 246 ( 41%) 360 (35%)

IHC N.E. 66 (14%) 2 (0.3%) 68 (5.3%)

IHC PMS2 107 (22%) 671 (83%) 778 (61%)

GENETIC TESTS 346 (72.%) 92 (11%) 465 (36%)

Genetic Test/IHC Def. 118/124 (95%) 72/284 (25%)

14 BRAF +

6 Met MLH!

190 /426 (38%)

Def . IHC rate : 33% ; IHC- & MSI H : 75% ; IHC+ & MSI H : 4 %

IHC MLH1

VA MI

MSH2

VA MI

MSH6

VA MI

PMS2

VA MI

TOT

NEG 23 45 27 35 1 5 1 - 137

POS 3 19 - 4 - 1 - - 27

NV 16 7 - 1 - - 24

TOT 106

(56%)

73 8 1 188

Raw Sensitivity :137/164 ( 83.5 %)

IHC MMR PPV: 72% ; PPV Mi : 72% Va : 72 %IHC PPV VUS: 12%

VUS MMR MUT: MI : n.36, 9 IHC- ,11MSI H, VA : n. 14 MSIH , 13 IHC –

84%

IHC & MSI (Milan)

Sensitivity , Specificty

MLH1 MSH2 MSH6 NO MMR

IHC Neg. 37 38 3 24

IHC POS. 22 6 1 136

MSI H 42 36 4 20

MSS 9 6 - 116

SENS. IHC : 78/107 : 73%MSI: 82/107 : 77%IHC +& MSI : 93/107 (87%, p. 001)

SENS IHC MLH1 : 68%

MSI MLH1 : 82%

( p:0.02 , OR :0.35)

SPECIFICITY IHC. : 82%

MSI : 83%

Logistic Regression : AC-IHC-MSI

� AC : MMR + 75%

0.2

50.5

00.7

51.0

0S

en

sitiv

ity

� CRC Site : Prox. MMR

+ 66%

0.0

00.2

5

0.00 0.25 0.50 0.75 1.001 - Specificity

Area under ROC curve = 0.9253

SensitivitySensitivitySensitivitySensitivity 86.92%86.92%86.92%86.92%SpecificitySpecificitySpecificitySpecificity 82.72%82.72%82.72%82.72%Positive predictive value 73.81%Negative predictive value 91.86%

Correctly Classified 84.23%

IHC PERFORMANCE

Selective screening

3/10

IHC neg .

IHC IHC - %MMR PPV

1320 CRC 33% 85% 72% IHC neg .

2//10 IHC neg

MMR Mut.

1/10

MMR Mut. IHC pos.IHC

SCREENING

1320 CRC 33% 85% 72%

Sens. 73%Spec. 82%