[558] TROP2 Expression in Various Tumors – A Potential Diagnostic Marker for Papillary Thyroid Carcinoma

Haiyan Liu, Jianhiu Shi, Fan Lin. Geisinger Medical Center, Danville, PA

Background: TROP2, a type 1 transmembrane protein, is encoded by tumor-associated calcium signal transducer 2 (TACSTD2), a member TACSTD gene family. TROP2 overexpression has been reported in some carcinomas (CA), including colorectal, gastric, oral and pancreatic CA. More recently, it has been actively studied as a prognostic marker. TROP2 expression by immunohistochemical analysis has not been extensively evaluated. In the current study, we immunohistochemically evaluated the expression of TROP2 in a large series of carcinomas from various organs using a Ventana staining system.
Design: Immunohistochemical evaluation of TROP2 (Santa Cruz Biotechnology, Inc., sc-376181) expression on TMA sections of 1,234 cases of carcinomas from various organs was performed. The staining intensity (membranous staining) was graded as weak or strong. The distribution was recorded as negative, 1+ to 4+.
Results: TROP2 expression was not identified in neuroendocrine tumors of pancreas and lung (N=78), testicular tumors (N=103), gastric adenocarcinoma (ADC, N=21), hepatocellular CA (N=18), invasive lobular CA of breast (N=31) or gastrointestinal stromal tumor (N=36). The expression of TROP2 on tumors from kidney, bladder, thyroid, breast, gynecologic, and gastrointestinal system is summarized in Table 1.

Table 1. Summary of TROP2 expression in Various CA
Diagnosis (N)1+ (N)2+ (N)3+ (N)4+ (N)Percentage (%)
Prostatic ADC (97)252926790%
Clear Cell RCC (82)02003%
ChRCC, Oncocytoma (30)01003%
Papillary RCC (18)121444%
PTC (48)510181090%
Follicular CA (37) and adenoma (51)30003%
Inv. UCA (43)4174058%
LGPUCA (38)121223100%
Esophageal CA (30)411020%
Colonic ADC (43)20005%
Pancreatic ADC (98)8101120%
Endometial ADC (131)283215460%
Endocervical ADC (25)080032%
Ovarian papillary serous CA (41)694046%
ADC of lung (44)1053041%
Squamous CA of lung (49)1155145%
Inv. Ductal CA of breast (110)101215437%
N-number of cases; CC:renal cell CA; ChRCC:chromophobe RCC; PTC:papillary thyroid CA; Inv. UCA:invasive urothelial CA; LGPUCA:non-invasive low grade papillary urothelial carcinoma

Conclusions: Our data suggest the potential diagnostic utility of TROP2 in: 1) differentiating PTC from follicular neoplasms (FA and FC); 2) suggesting PRCC in renal tumors if positive; 3) suggesting ductal CA over lobular CA if positive; 4) if diffusely positive in urothelial CA, likely LGPUCA. Weak or negative expression in invasive UCA suggests that TROP2 may play a role in tumor progression.
Category: Endocrine

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 67, Wednesday Afternoon


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