Abstract
TROP2 is a glycoprotein which is expressed in carcinomas rather than normal tissues and associated with poor prognosis. Immunohistohemical TROP2 staining was determined to be useful for diagnosing papillary thyroid carcinoma (PTC). In this study, we aimed to find out relationship between TROP-2 expression and the diagnosis of PTC, and clinico pathological parameters. This retrospective study was conducted on 270 cases (145 malignant and 124 benign). All histopathological parameters were re-evaluated blindly. We used 3 different scores for positivity for TROP2 expression (TES: Total estimation score, 5%, IRS:Immunoreactive score). Sensitivity was respectively according to TES, 5%and IRS; 55.5%, 54.1%, 51.4%. Specificity was 98.4% in all different scores. TROP2 positivity was correlated with older age in 5% score and TES. Absence of encapsulation, presence of infiltrating spreading, perineural invasion, extra thyroidal extension, tall cell and/or hobnail differentiation were associated with TROP2 expression in three different scores. Presence of lymphatic invasion was correlated with TROP2 positivity in 5% score and IRS. TROP2 expression was inversely proportional to follicular variant PTC and tumour size in 5% score. TROP-2 is a marker for aggressive behaviour rather than detecting malignancy, but if it stained and not malignant, it may also have potential for determining precursor lesion that demands further studies. Additionally, in 3 different scores, TES was most sensitive, but most variable that had correlation with TROP2 was seen at 5% score.
Keywords: TROP2, Thyroid carcinoma, Immunohistochemistry, Aggresive behavior
Introduction
Human trophoblastic cell-surface antigen 2 (TROP2) is a transmembrane glycoprotein which is expressed in carcinomas rather than normal tissues and associated with poor prognosis [1–3].This protein is related to tumor progression and metastasis via regulating the phosphatidylinositol 3 kinase(PI3K)/protein kinase B pathway causing epithelial-mesenchymal transition [4]. TROP2 also increase invasion due to activation of MAPK (mitogen-activated protein kinase) in thyroid [5]. PI3K and MAPK pathway are affected in thyroid malignancy [6].
Papillary thyroid carcinomas(PTC) is most frequent thyroid carcinomas and mostly have good prognosis, however infrequently recurrence, metastasis and radioiodine resistance can happen, so new markers are required to determine the aggressiveness of each individual case and to make targeted therapy and surveillance [7–9]. TROP2 may have potential to close this gap and immunhistochemical TROP2 staining was determined to be useful for diagnosing PTC [10, 11].
In this study, we aimed to find out contribution of TROP-2 expression to the diagnosis of PTC, the relationship between age, gender, histopathological parameters, which may be sign of aggressive behaviour, such as, extra thyroidal extension, lympho vascular invasion, tall cell and/or hobnail differentiation etc. in PTC and immunohistochemical TROP-2 expression.
Method
This retrospective study was conducted on 270 cases which have gone thyroidectomy from 2004 to 2015 at Haydarpasa Numune Training and Research Hospital. There were 145 malignant (142 PTC, 2 follicular carcinoma, 1 PTC + poorly differentiated carcinoma, 1 PTC + medullary thyroid carcinoma), 124 benign (12 follicular nodular disease, 16 lymphocytic thyroiditis,7 hashimato disease, 33 follicular adenoma, 12 oncocytic follicular adenoma, 44 non-invasive follicular thyroid neoplasm with papillary like nuclear features(NIFTP)) cases, collected from the archives of the Pathology Department.
Histopathological Assessment
All histopathological parameters were re-evaluated blindly and assentment was done only in PTC cases because of insufficient cases of other malignancy. Follicular variant PTC (FVPTC) were accepted if tumor comprised mostly follicles and no papilla was seen [12]. If tumour have area of tall cell or hobnail regardless of percentage, it was accepted tall cell and/or hobnail differentiation (THD). This 2 differentiation was combined due to aggressive behaviour of these components. Areas of solid or oncocytic regardless of percentage were accepted differentiation in itself. Parameter of infiltrative spreading(IS) were defined as positive if tumour have spiculated borders or more than 3 structures consist of follicles invasing parenchyme [13].
Immunohistochemistry (Antibody and Staining)
Sections of 4 micron were taken in slides with poly-L-Lysin. Slides were kept for overnight at 37 °C, 15 min at 78 °C, for the deparaffinization process, undergone Xylen for 25 min, in order of decreasing alcohols for 10 min, washed with distilled water. Slides were placed in pH 6 citrate buffer solution, antigen retrieval was performed in the decloaking chamber set at 115 °C. After standing at room temperature for 15 min, they were washed with phosphate buffered saline (PBS) (3 times), periphery of tissues were drawn with hydrophobic pen, 3% hydrogen peroxide solution was dropped and kept for 5 min. After washing with PBS, blockage (Super blok ScyTek Labaratories Logan, Utah, USA) was done. After washing with PBS, TROP-2 antibody (Clone F5: sc-376181, mouse monoclonal antibody, Santa Cruz Biotechnology, Inc.) was applied at 1/50 dilution, kept for 1 h. After washing with PBS, Biotinylated Goat Anti-Mouse (link) was dropped, kept for 20 min. After washing with PBS (3 times), streptavidin peroxidase (label) was dropped, kept for 20 min, they were washed with PBS. DAB(diaminobenzidine) chromogen(ScyTek Labaratories Logan, Utah, USA) was dropped, the tissues were kept for a maximum of 5 min until coloring. After washing with tap water, they were stained with hematoxilen. After washing with tap water, they were undergone alcohol and xylene. As positive control, validated classic papillary tyhroid carcinoma was used.
Immunohistochemical Interpretation
We used 3 different score;
Total estimation score(TES): There were 4 positive categories (1–25% = 1; 26–50% = 2; 51–75% = 3; 76–100% = 4). 1% and above any membranous staining was considered positive.
5% and above any membranous staining was considered positive.
Immunoreactive score of Remmele and Stegner (IRS): Percentage and average intensity of membranous staining was used. There were 5 percentage (No positive cell = 0; < %10 = 1,10–50% = 2;51–80% = 3; > 80% = 4) and 4 intensity (no reaction = 0;mild = 1;intermediate = 2;strong = 3) categories. IRS (0–12) = PercentageX intensity of staining. Total score 0–1 = Negative (1); 2–3 = Positive weak expression (2); 4–8 = Positive intermediate expression (3), 9–12 = Positive strong expression(4).
Statistical Analysis
Our data was analysed by using IBM SPSS Statistics 22 (IBM SPSS for Windows version 22, IBM Corporation, Armonk, New York, United States). Kolmogorov–Smirnov test was utilized for suitability of variables to normal distribution. Sensitivity and specificity were calculated for assessment of diagnostic test. We evaluated our findings according to chi square and Fischer’s Exact test for comparing qualitative variables and Mann Whitney U test for comparing quantitative variables. p values less than 0.05 were considered statistically significant.
Results
TROP2 positivity was seen in 81(55.5%)malignant cases according to TES, 79 (59.1%) malignant cases according to 5%, 75(51.4%) malignant cases according to IRS. Only 2 benign (NIFTP) cases were positive in three different scores. Periphery of tumour or benign areas were not stained. Sensitivity was respectively according to TES, 5%and IRS; 55.5%, 54.1%, 51.4%. Specificity was 98.4% in all different scores. Sensitivity and specificity are shown at Table 1.
Table 1.
TROP expression at diagnosing malignancy
| Score | Malignantn n (%) |
Benignn n (%) |
Sensivity % |
Spesificity % |
Accuracy % |
|
|---|---|---|---|---|---|---|
| TES (≥ 1%) | Positive | 81 (55.5) | 2 (1.6) | 55.5 | 98.4 | 75.4 |
| Negative | 65 (44.5) | 122 (98.4) | ||||
|
5% score (≥ 5%) |
Positive | 79 (54.1) | 2 (1.6) | 54.1 | 98.4 | 74.7 |
| Negative | 67 (45.9) | 122 (98.4) | ||||
| IRS (> 1) | Positive | 75 (51.4) | 2 (1.6) | 51.4 | 98.4 | 73.2 |
| Negative | 71 (48.6) | 122 (98.4) | ||||
TROP2 positivity was correlated with older age in 5% score and TES. In %5 score, positive mean and standard deviation of age was 52,14 ± 13,33. Absence of encapsulation (AE), presence of IS, perineural invasion (PNI), extrathyroidal extension (ETE), THD were associated with TROP2 expression in three different scores. In 5% score, positivity was seen in 67 of 95 cases in the AE, 63 of 86 cases in IS, 13 of 15 cases in PNI, 36 of 46 cases in minimal ETE, 26 of 31 cases in THD. Presence of lymphatic invasion (LI) was correlated with TROP2 positivity in 5% and IRS. In 5% score, positivity was seen in 14 of 18 cases in LI. TROP2 expression was inversely proportional to FVPTC and tumour size in 5% score. TROP2 expression was seen in 14 of 35 cases(FVPTC). Median (Minimum-Maximum) of tumour size was 1200 mm(2,00–130,00). Relationship between TROP2 positivity and all the other parameters were not significant. Relationship between TROP2 positivity and age, gender, histopathological parameters are shown at Table 2 for 5% score, Table 3 for TES, Table 4 for IRS. TROP2 staining was shown at Fig. 1.
Table 2.
Relationship between TROP2 positivity and age,gender, histopathological parameters according to 5% score
| Trop2%5 | ||||
|---|---|---|---|---|
| Negative n (%) |
Positive n (%) |
p | ||
| Age Mean ± SD | 46.05 ± 12.73 | 52.14 ± 13.33 | 0.006* | |
| Age (45) | < 45 | 28 (43.8) | 25 (32.1) | 0.152 |
| ≥ 45 | 36 (56.3) | 53 (67.9) | ||
| Gender | Women | 55 (85.9) | 61 (78.2) | 0.236 |
| Men | 9 (14.1) | 17 (21.8) | ||
| Tumor size, Median(Min–Max) | 15.00 (3.00–80.00) | 12.00 (2.00–130.00) | 0.069 | |
| Tumor size(1 cm) | < 1 cm | 23 (35.9) | 27 (34.6) | 0.870 |
| ≥ 1 cm | 41 (64.1) | 51 (65.4) | ||
| Encapsulation | No | 28 (43.8) | 67 (85.9) | p < 0.001* |
| Yes | 36 (56.3) | 11 (14.1) | ||
|
Tumor capsule invasion |
No | 22 (61.1) | 7 (63.6) | 0.792 |
| Yes, minimal | 10 (27.8) | 2 (18.2) | ||
| Yes, widely | 4 (11.1) | 2 (18.2) | ||
| Spreading | Noninfiltative | 41 (64.1) | 15 (19.2) | p < 0.001* |
| Infiltrative | 23 (35.9) | 63 (80.8) | ||
| Perineural invasion | No | 62 (96.9) | 65 (83.3) | 0.008* |
| Yes | 2 (3.1) | 13 (16.7) | ||
| Lymphatic invasion | No | 60 (93.8) | 64 (82.1) | 0.031* |
| Yes, | 4 (6.3) | 14 (17.9) | ||
| Angioinvasion | No | 60 (93.8) | 76 (97.4) | 0.252 |
| Yes,focal | 4 (6.3) | 2 (2.6) | ||
| Extrathyroidal extension | No | 54 (84.4) | 42 (53.8) | p < 0.001* |
| Yes, minimal | 10 (15.6) | 36 (46.2) | ||
| Lymph node metastasis | No | 15 (78.9) | 18 (58.1) | 0.113 |
| Yes | 4 (21.1) | 13 (41.9) | ||
| LT** | No | 41 (65.1) | 48 (61.5) | 0.665 |
| Yes | 22 (34.9) | 30 (38.5) | ||
| Onkositic differantiation | No | 28 (43.8) | 28 (35.9) | 0.341 |
| Yes | 36 (56.3) | 50 (64.1) | ||
| Solid differantiation | No | 53 (82.8) | 69 (88.5) | 0.336 |
| Yes | 11 (17.2) | 9 (11.5) | ||
| THD** | No | 59 (92.2) | 52 (66.7) | p < 0.001* |
| Yes | 5 (7.8) | 26 (33.3) | ||
| FVPTC** | Folicular | 21 (32.8) | 14 (17.9) | 0.041* |
| Nonfolicular | 43 (67.2) | 64 (82.1) | ||
Fisher exact test; Chi-square test; α:0.05; Independent samples t test; Mann–Whitney U test
*Statistical significance. **LT lymphocytic thyroiditis at nontumoral area, THD tall cell and/or hobnail differantiation, FVPTC folicular variant papillary thyroid carcinoma
Table 3.
Relationship between TROP2 positivity and age,gender, histopathological parameters according to TES
| TROP2 TES | |||||||
|---|---|---|---|---|---|---|---|
| Negative n (%) |
1–25 n (%) |
26–50 n (%) |
51–75 n (%) |
76–10 n (%) |
p | ||
|
Age, Median (Min–Max) |
47.50 (20.00–76.00) | 51.00 (27.00–75.00) | 56.00 (35.00–89.00) | 45.00 (34.00–86.00) | 62.00-(49.00–62.00) | 0.029* | |
| Age (45) | < 45 | 27 (43.5) | 15 (38.5) | 7 (24.1) | 4 (44.4) | 0 (0.0) | 0.278 |
| ≥ 45 | 35 (56.5) | 24 (61.5) | 22 (75.9) | 5 (55.6) | 3 (100) | ||
| Gender | Women | 53 (85.5) | 31 (79.5) | 21 (72.4) | 9 (100) | 2 (66.7) | 0.304 |
| Men | 9 (14.5) | 8 (20.5) | 8 (27.6) | 0 (0.0) | 1 (33.3) | ||
| Tumor size, Median (Min–Max) | 15.00 (3.00–80.00) | 12.00 (2.00–50.00) | 11.00 (2.00–130.00) | 13.00 (3.00–35.00) | 3.00 (2.00–12.00) | 0.063 | |
|
Tumor size (1 cm) |
< 1 cm | 23 (37.1) | 16 (41.0) | 7 (24.1) | 2 (22.2) | 2 (66.7) | 0.385 |
| ≥ 1 cm | 39 (62.9) | 23 (59.0) | 22 (75.9) | 7 (77.8) | 1 (33.3) | ||
| E* | No | 26 (41.9) | 31 (79.5) | 27 (93.1) | 9 (100.0) | 2 (66.7) | p < 0.001* |
| Yes | 36 (58.1) | 8 (20.5) | 2 (6.9) | 0 (0.0) | 1 (33.3) | ||
| Tumor capsule invasion | No | 22 (61.1) | 5 (62.5) | 1 (50.0) | 0 (0.0) | 1 (100) | 0.854 |
| Yes, minimal | 10 (27.8) | 1 (12.5) | 1 (50.0) | 0 (0.0) | 0 (0.0) | ||
| Yes, widely | 4 (11.1) | 2 (25.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||
| Spreading | Noninfiltative | 41 (66.1) | 10 (25.6) | 3 (10.3) | 1 (11.1) | 1 (33.3) | p < 0.001* |
| Infiltrative | 21 (33.9) | 29 (74.4) | 26 (89.7) | 8 (88.9) | 2 (66.7) | ||
|
Perineural invasion |
No | 61 (98.4) | 34 (87.2) | 24 (82.8) | 5 (55.6) | 3 (100) | 0.003* |
| Yes | 1 (1.6) | 5 (12.8) | 5 (17.2) | 4 (44.4 | 0 (0.0) | ||
|
Lymphatic invasion |
No | 58 (93.5) | 33 (84.6) | 23 (79.3) | 7 (77.8) | 3 (100) | 0.234 |
| Yes | 4 (6.5) | 6 (15.4) | 6 (20.7) | 2 (22.2) | 0 (0.0) | ||
| AI** | No | 58 (93.5) | 38 (97.4) | 28 (96.6) | 9 (100.0) | 3 (100) | 0.733 |
| Yes, focal | 4 (6.5) | 1 (2.6) | 1 (3.4) | 0 (0.0) | 0 (0.0) | ||
| ETE** | No | 54 (87.1) | 21 (53.8) | 13 (44.8) | 5 (55.6) | 3 (100) | 0.001* |
| Yes, minimal | 8 (12.9) | 18 (46.2) | 16 (55.2) | 4 (44.4) | 0 (0.0) | ||
| Lymph node metastasis | No | 15 (83.3) | 11 (61.1) | 4 (57.1) | 2 (33.3) | 1 (100) | 0.180 |
| Yes | 3 (16.7) | 7 (38.9) | 3 (42.9) | 4 (66.7) | 0 (0.0) | ||
| LT** | No | 39 (63.9) | 29 (74.4) | 17 (58.6) | 3 (33.3) | 1 (33.3) | 0.136 |
| Yes | 22 (36.1) | 10 (25.6) | 12 (41.4) | 6 (66.7) | 2 (66.7) | ||
|
Onkositic D** |
No | 28 (45.2) | 11 (28.2) | 12 (41.4) | 4 (44.4) | 1 (33.3) | 0.563 |
| Yes | 34 (54.8) | 28 (71.8) | 17 (58.6) | 5 (55.6) | 2 (66.7) | ||
|
Solid D** |
No | 51 (82.3) | 33 (84.6) | 27 (93.1) | 9 (100.0) | 2 (66.7) | 0.345 |
| Yes | 11 (17.7) | 6 (15.4) | 2 (6.9) | 0 (0.0) | 1 (33.3) | ||
| THD** | No | 58 (93.5) | 27 (69.2) | 16 (55.2) | 7 (77.8) | 3 (100) | p < 0.001* |
| Yes | 4 (6.5) | 12 (30.8) | 13 (44.8) | 2 (22.2) | 0 (0.0) | ||
| FVPTC** | Folicular | 20 (32.3) | 7 (17.9) | 6 (20.7) | 2 (22.2) | 0 (0.0) | 0.389 |
| Nonfolicular | 42 (67.7) | 32 (82.1) | 23 (79.3) | 7 (77.8) | 3 (100) | ||
Fisher exact test; Chi-square test; α:0.05; One-Way Anova; Kruskal Wallis H test
*Statistical significance. **E encapsulation, AI angioinvasion, ETE extrathyroidal extension, LT lymphocytic thyroiditis at nontumoral area, D differantiation, THD tall cell and/or hobnail differantiation, FVPTC: foliculer variant papillary thyroid carcinoma
Table 4.
Relationship between TROP2 positivity and age, gender, histopathological parameters according to IRS
| TROP2 IRS | p | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Negative n (%) | Weak positive n (%) | Intermediate positive n (%) | Strong positive n (%) | |||||||
| Age, Median (Min–Max) | 48.0 (20.0–76.0) | 52.0 (28.0–66.0) | 51.5 (27.0–89.0) | 49.5 (34.0–86.0) | 0.352 | |||||
| Age (45) | < 45 | 28 (41.2) | 4 (40.0) | 17 (32.7) | 4 (33.3) | 0.810 | ||||
| ≥ 45 | 40 (58.8) | 6 (60.0) | 35 (67.3) | 8 (66.7) | ||||||
| Gender | Women | 59 (86.8) | 8 (80.0) | 38 (73.1) | 11 (91.7) | 0.195 | ||||
| Men | 9 (13.2) | 2 (20.0) | 14 (26.9) | 1 (8.3) | ||||||
| Tumor size, Median (Min–Max) | 13.5 (3.0–80.0) | 12.0 (7.0–25.0) | 12.0 (2.0–130.0) | 13.0 (2.0–35.0) | 0.697 | |||||
|
Tumor size (1 cm) |
< 1 cm | 27 (39.7) | 3 (30.0) | 16 (30.8) | 4 (33.3) | 0.778 | ||||
| ≥ 1 cm | 41 (60.3) | 7 (70.0) | 36 (69.2) | 8 (66.7) | ||||||
| Encapsulation | No | 29 (42.6) | 7 (70.0) | 48 (92.3) | 11 (91.7) | p < 0.001* | ||||
| Yes | 39 (57.4) | 3 (30.0) | 4 (7.7) | 1 (8.3) | ||||||
|
Tumor capsule invasion |
No | 25 (64.1) | 2 (66.7) | 1 (25.0) | 1 (100) | 0.542 | ||||
| Yes, minimal | 10 (25.6) | 0 (0.0) | 2 (50.0) | 0 (0.0) | ||||||
| Yes, widely | 4 (10.3) | 1 (33.3) | 1 (25.0) | 0 (0.0) | ||||||
| Spreading | Noninfiltative | 44 (64.7) | 4 (40.0) | 6 (11.5) | 2 (16.7) | p < 0.001* | ||||
| Infiltrative | 24 (35.3) | 6 (60.0) | 46 (88.5) | 10 (83.3) | ||||||
|
Perineural invasion |
No | 66 (97.1) | 9 (90.0) | 44 (84.6) | 8 (66.7) | 0.009* | ||||
| Yes | 2 (2.9) | 1 (10.0) | 8 (15.4) | 4 (33.3) | ||||||
| Lymphatic invasion | No | 64 (94.1) | 10 (100) | 40 (76.9) | 10 (83.3) | 0.024* | ||||
| Yes | 4 (5.9) | 0 (0.0) | 12 (23.1) | 2 (16.7) | ||||||
| Angioinvasion | No | 64 (94.1) | 10 (100) | 50 (96.2) | 12 (100) | 0.749 | ||||
| Yes, focal | 4 (5.9) | 0 (0.0) | 2 (3.8) | 0 (0.0) | ||||||
| ETE** | No | 59 (86.8) | 4 (40.0) | 25 (48.1) | 8 (66.7) | p < 0.001* | ||||
| Yes, minimal | 9 (13.2) | 6 (60.0) | 27 (51.9) | 4 (33.3) | ||||||
| Lymph node metastasis | No | 16 (84.2) | 2 (50.0) | 12 (60.0) | 3 (42.9) | 0.153 | ||||
| Yes | 3 (15.8) | 2 (50.0) | 8 (40.0) | 4 (57.1) | ||||||
| LT** | No | 43 (64.2) | 7 (70.0) | 35 (67.3) | 4 (33.3) | 0.163 | ||||
| Yes | 24 (35.8) | 3 (30.0) | 17 (32.7) | 8 (66.7) | ||||||
| Onkositic differantiation | No | 31 (45.6) | 2 (20.0) | 18 (34.6) | 5 (41.7) | 0.370 | ||||
| Yes | 37 (54.4) | 8 (80.0) | 34 (65.4) | 7 (58.3) | ||||||
|
Solid differantiation |
No | 55 (80.9) | 7 (70.0) | 49 (94.2) | 11 (91.7) | 0.072 | ||||
| Yes | 13 (19.1) | 3 (30.0) | 3 (5.8) | 1 (8.3) | ||||||
| THD** | No | 63 (92.6) | 8 (80.0) | 30 (57.7) | 10 (83.3) | 0.001* | ||||
| Yes | 5 (7.4) | 2 (20.0) | 22 (42.3) | 2 (16.7) | ||||||
| FVPTC** | Folicular | 22 (32.4) | 1 (10.0) | 10 (19.2) | 2 (16.7) | 0.217 | ||||
| Nonfolicular | 46 (67.6) | 9 (90.0) | 42 (80.8) | 10 (83.3) | ||||||
Fisher exact test; Chi-square test; α:0.05; One-Way Anova; Kruskal Wallis H test
*Statistical significance. **ETE extrathyroidal extension, LT lymphocytic thyroiditis at nontumoral area, D differantiation, THD tall cell and/or hobnail differantiation, FVPTC folicular variant papillary thyroid carcinoma
Fig. 1.
TROP2 staining. a Intermediate membranous staining at follicles of non-invasive follicular thyroid neoplasm with papillary like nuclear features (× 400). b Membranous staining at structures of papillae at the area of in tall cell differantiation(× 200) c Intermediate membranous staining at area of hobnail differantiation(× 400). d Strong membranous staining at papillary thyroid carcinoma and no staining at stroma or lymphocyte (× 400)
Discussion
TROP2 which is a glycoprotein which is expressed in many carcinomas including gastric, ovarian, gallbladder and oral, rather than normal tissues [1–4], staining was determined to be useful for diagnosing PTC/malignancy. In studies, sensitivity varies between 18.8% and 98.1%. Specificity varies between 74 and 100%. Very low value may be related to NIFTP (Formerly FVPTC). In our study sensitivity was respectively according to TES, 5%and IRS; 55.5%, 54.1%, 51.4%. Specificity was 98.4% in three different scores. These findings mostly are near the study of Afsin et al. In all other studies, sensitivity was high after definition of NIFTP (After year of 2017). Sensitivity and specificity of studies are shown at Table 5. In our study only 2 benign (NIFTP) cases are positive. These cases that in order of had size of 7 mm and 4 mm, showed oncocytic differentiation, respectively 5% strong and 10% intermediate TROP2 membranous staining. All other benign entities (122 case) are negative. In literature, TROP2 staining may be seen rarely at nonneoplastic thyroid, hyperplasitic papilla, hashimoto thyroiditis, follicular and oncocytic adenoma but we saw no staining in these cases that is similar to the studies of Simms et al. and Afsin et al. Bychkov et al. used H score (According to percentage of each intensity) for TROP2 and saw no positivity for benign entities or nontumoral area.[10, 11, 15–20]. We had high specificity that may depend on monoclonal antibody, so these staining of benign thyroid tissue may be related to antibody/technical reasons or a starting sign of malignant transformation, inasmuch as TROP2 expression is seen at dysplasia of stomach [21] as we saw in NIFTP, so this staining may mean showing the capacity of NIFTP to develop into PTC, but not due to oncocytic differentiation. Because, there was not relationship between TROP2 positivity and oncocytic differentiation in PTC in our study. However these interpretation is limited, can change with increasing cases. Many of studies utilized 5% score, we used 3 different score. TES (≥ 1%) is most sensitive and may be most accurate. There were 2 cases that were PTC, had staining of below the 5% (1%) and one of them had metastasis in our study. Also we saw strong and intermediate staining in NIFTP, so most important point may be percentage or proportion but not intensity.
Table 5.
Sensivity and specificity of TROP2 in studies at determining malignancy/PTC
| Antibody | Sensitivity | Specificity | |
|---|---|---|---|
| Our study | F5: sc-376181, mouse monoclonal, Santa Cruz Biotechnology. 1/50 dilution |
55.5 (≥ 1%,TES) 54.1(5% score) 51.4(IRS) |
98.4(≥ 1%,TES) 98.4 (5% score) 98.4(IRS) |
| [19] | Purified goat polyclonal antibody, R&D Systems, Inc., Minneapolis, MN, USA. 1/100 dilution | 87% (5% score) | 89%(5% score) |
| [18] | F-5, Cat sc-376181, Santa Cruz. 1/40 dilution |
CVPTC:90 FVPTC: 18.8 (5% score) |
CVPTC: 95.2 FVPTC: 79.5 (5%score) |
| [10] | F5: Sc-376181, mouse monoclonal, Santa Cruz Biotechnology. 1/100 dilution |
PTC:75.4(> 13.79 H score) CVPTC: 98.1 (> 30.65 H score) |
|
| [17] |
F5: Sc-376181. Santa Cruz Biotechnology 1/50 dilution |
CVPTC:94% FVPTC: 81% (5% score) |
|
| [15] | B-9, Medaysis, Alameda, CA, USA | 93% (5% score) | 74%(5% score) |
| [11] | Rabbit, polyclonal, GeneTex. 1/150 dilution | 50%(≥ 1%,TES) | 100%(≥ 1%,TES) |
| [16] | AF560, goat, R & D, USA. 1/200 dilution | 96 (≥ 10% score) | 87.5 (≥ 10% score) |
| [14] | F5: Sc-376181, mouse monoclonal, Santa Cruz Biotechnology. 1/50 dilution | 71% (Percentage) | 81%(Percentage) |
CVPTC classic variant papillary thyroid carcinoma, FVPTC folicular variant papillary thyroid carcinoma
Molecular profile of advanced thyroid carcinoma are mostly MAPK pathway (68%) which includes frequently BRAF mutation (48%), and rarely PI3K/AKT pathway. These pathways seldom can be commutated, that is associated with resistance to direct targeted therapy [6]. TROP2 is related to these 2 pathways [4, 5]. TROP2 also promotes multidrug resistance and associated with metastasis, poor prognosis [1–3, 22]. These features may make TROP2 a candidate marker that determine the aggressiveness of tumour and possible target for therapy in thyroid. There are need for studies to understand relationship between TROP2 and these pathways in thyroid. However clinico pathological parameters that can show poor behaviour can make a sign how TROP2 affect tumour in thyroid.
FVPTC shows more negativity, non-follicular PTC shows more positivity, lymph node metastasis and gender are not correlated with TROP2 in one study like ours, but age, tumour size and extra thyroidal extension are not related to TROP2 expression unlike ours [23]. In our study relation of gender may not optimal due to insufficiency of male cases. In another study, TROP2 overexpression is related to LNM, ETE, maximum diameter and TROP2 expression is an independent risk factor for LNM [24]. In our study, TROP2 positivity was correlated with ETE and small tumour size, but not LNM. Inverse relation of tumour size may be explained due to accumulation of larger tumours which were follicular variant and/or with encapsulation showing negativity. LNM was not correlated with TROP2, but this may change with increasing cases. Because positivity of metastasis was more than negativity of metastasis. Additionally, lymphatic invasion that shows potential to make LNM, and presence of IS which may be predictor of lymph node metastasis [13] were associated with TROP2. Also, AE, PNI and THD that showing infiltrative behaviour of tumour, were related to TROP2 expression. In studies, TROP2 expression is related to BRAF V600E mutation [23, 24] that have associated with old age, more aggressive growth pattern and behaviour, large tumour size, LNM [25]. Our results and BRAF relation to TROP2 may mostly support each other due to these variables of poor behaviour.
Relationship between TROP2 positivity and all the other parameters were not significant, but parameters of solid differentiation, angioinvasion and capsule invasion were limited because of unsatisfactory number of the cases. Although oncocytic differentiation may have adequate cases, result might change with increasing cases inasmuch as positivity of oncocytic tumour was more than negativity. In three different scores, TES was most sensitive, but most variable that had correlation with TROP2 was seen at 5% score.
In our study, TROP is a marker for infiltrative and aggressive nature of PTC rather than detecting malignancy/PTC, so it may effect the scope of surgery and therapy but if it stained, that means most likely malignancy, if not malignant, it may also have potential for determining precursor lesion that demands further studies.
Funding
This study was funded partially by Haydarpasa Numune Training and Research Hospital.
Availability of Data and Material
Not available due to patient privacy.
Compliance with Ethical Standards
Conflict of interest
There are no conflict of interest.
Ethical Approval
This study was approved by ethics committee (Decision number HNEAH-KAEK 2015/61). This study was produced from speciality thesis. Also some PTC cases were re-named as NIFTP after re-evaluation.
Footnotes
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References
- 1.Zhao W, Zhu H, Zhang S, Yong H, Wang W, Zhou Y, Wang B, Wen J, Qiu Z, ding G, , et al. Trop2 is overexpressed in gastric cancer and predicts poor prognosis. Oncotarget. 2016;7:6136–6145. doi: 10.18632/oncotarget.6733. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Tang G, Tang Q, Jia L, et al. (2018) High expression of TROP2 is correlated with poor prognosis of oral squamous cell carcinoma. Pathol Res Pract. 2018;214(10):1606–1612. doi: 10.1016/j.prp.2018.07.017. [DOI] [PubMed] [Google Scholar]
- 3.Xu N, Zhang Z, Zhu J, Xu L, Li Y, Duan L, Mao Y, Li H. Overexpression of trophoblast cell surface antigen 2 as an independent marker for a poor prognosis and as a potential therapeutic target in epithelial ovarian carcinoma. Int J Exp Pathol. 2016;97:150–158. doi: 10.1111/iep.12174. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Li X, Teng S, Zhang Y, Zhang W, Zhang X, Xu K, Yao H, Yao J, Wang H, Liang X. TROP2 promotes proliferation, migration and metastasis of gallbladder cancer cells by regulating PI3K/AKT pathway and inducing EMT. Oncotarget. 2017;8:47052–47063. doi: 10.18632/oncotarget.16789. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Guan H, Guo Z, Liang W, et al. Trop2 enhances invasion of thyroid cancer by inducing MMP2 through ERK and JNK pathways. BMC Cancer. 2017;17(1):486. doi: 10.1186/s12885-017-3475-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Chen H, Luthra R, Routbort MJ, et al. Molecular profile of advanced thyroid carcinomas by next-generation sequencing: characterizing tumors beyond diagnosis for targeted therapy. Mol Cancer Ther. 2018;17(7):1575–1584. doi: 10.1158/1535-7163.MCT-17-0871. [DOI] [PubMed] [Google Scholar]
- 7.Katoh H, Yamashita K, Enomoto T, Watanabe M. Classification and general considerations of thyroid cancer. Ann Clin Pathol. 2015;3(1):1045. [Google Scholar]
- 8.Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin. 2011;61:69–90. doi: 10.3322/caac.20107. [DOI] [PubMed] [Google Scholar]
- 9.Kowalska A, Walczyk A, Kowalik A, Palyga I, Gasior-Perczak D, Trybek T, et al. Response to therapy of papillary thyroid cancer of known BRAF status. Cin Endocrinol (Oxf) 2017;87:815–824. doi: 10.1111/cen.13423. [DOI] [PubMed] [Google Scholar]
- 10.Bychkov A, Sampatanukul P, Shuangshoti S, Keelawat S. TROP-2 immunohistochemistry: a highly accurate method in the differential diagnosis of papillary thyroid carcinoma. Pathology. 2016;48(5):425–433. doi: 10.1016/j.pathol.2016.04.002. [DOI] [PubMed] [Google Scholar]
- 11.Murtezaoglu AR, Gucer H. Diagnostic value of TROP-2 expression in papillary thyroid carcinoma and comparison with HBME-1, galectin-3 and cytokeratin 19. Pol J Pathol. 2017;68(1):1–10. doi: 10.5114/pjp.2017.67610. [DOI] [PubMed] [Google Scholar]
- 12.Elsheikh TM, Asa SL, Chan JK, DeLellis RA, Heffess CS, LiVolsi VA, Wenig BM. Interobserver and intraobserver variation among experts in the diagnosis of thyroid follicular lesions with borderline nuclear features of papillary carcinoma. Am J Clin Pathol. 2008;130:736–744. doi: 10.1309/AJCPKP2QUVN4RCCP. [DOI] [PubMed] [Google Scholar]
- 13.Jung YY, et al. Characteristic tumor growth patterns as novel histomorphologic predictors for lymph node metastasis in papillary thyroid carcinoma. Hum Pathol. 2013;44(12):2620–2627. doi: 10.1016/j.humpath.2013.07.025. [DOI] [PubMed] [Google Scholar]
- 14.Abdou AG, Shabaan M, Abdallha R, Nabil N. Diagnostic value of TROP-2 and CK19 expression in papillary thyroid carcinoma in both surgical and cytological specimens. Clin Pathol. 2019 doi: 10.1177/2632010X19863047. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Zargari N, Mokhtari M. Evaluation of diagnostic utility of immunohistochemistry markers of TROP-2 and HBME-1 in the diagnosis of thyroid carcinoma. Eur Thyroid J. 2019;8(1):1–6. doi: 10.1159/000494430. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Yang X, Hu Y, Shi H, et al. The diagnostic value of TROP-2 SLP-2 and CD56 expression in papillary thyroid carcinoma. Eur Arch Otorhinolaryngol. 2018;275(8):2127–2134. doi: 10.1007/s00405-018-5045-x. [DOI] [PubMed] [Google Scholar]
- 17.Liu H, Shi J, Lin F. The potential diagnostic utility of TROP-2 in thyroid neoplasms. Appl Immunohistochem Mol Morphol. 2017;25(8):525–533. doi: 10.1097/PAI.0000000000000332. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Simms A, Jacob RP, Cohen C, Siddiqui MT. TROP-2 expression in papillary thyroid carcinoma: potential diagnostic utility. Diagn Cytopathol. 2016;44(1):26–31. doi: 10.1002/dc.23382. [DOI] [PubMed] [Google Scholar]
- 19.Addati T, Achille G, Centrone M, et al. TROP-2 expression in papillary thyroid cancer: a preliminary cyto-histological study. Cytopathology. 2015;26(5):303–311. doi: 10.1111/cyt.12196. [DOI] [PubMed] [Google Scholar]
- 20.Tang G, Tang Q, Jia L, et al. TROP2 increases growth and metastasis of human oral squamous cell carcinoma through activation of the PI3K/Akt signaling pathway. Int J Mol Med. 2019;44(6):2161–2170. doi: 10.3892/ijmm.2019.4378. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Riera KM, Jang B, Min J, et al. Trop2 is upregulated in the transition to dysplasia in the metaplastic gastric mucosa. J Pathol. 2020 doi: 10.1002/path.5469. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Kuai X, Jia L, Yang T, et al. Trop2 promotes multidrug resistance by regulating notch1 signaling pathway in gastric cancer cells. Med Sci Monit. 2020;26:e919566 . doi: 10.12659/MSM.919566. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Kong JS, Kim HJ, Kim MJ, et al. The significance of TROP2 expression in predicting BRAF mutations in papillary thyroid carcinoma. J Pathol Transl Med. 2018;52(1):14–20. doi: 10.4132/jptm.2017.10.17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Guan Q, Wang Y, Liao T, et al. Overexpression of trophoblast cell surface antigen 2 is associated with BRAF V600E mutation and aggressive behavior in papillary thyroid cancer. Int J Clin Exp Pathol. 2018;11(8):4130–4139. [PMC free article] [PubMed] [Google Scholar]
- 25.Gan X, Shen F, Deng X, et al. Prognostic implications of the BRAF-V600E mutation in papillary thyroid carcinoma based on a new cut-off age stratification. Oncol Lett. 2020;19(1):631–640. doi: 10.3892/ol.2019.11132. [DOI] [PMC free article] [PubMed] [Google Scholar]
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Not available due to patient privacy.