Microarrays of bladder cancer tissue are highly representative of proliferation index and histological grade

Tissue microarrey: a potential cost-effective approach for mismatch repair testing in colorectal cancer

BACKGROUND

Deficiencies in Mismatch Repair (MMR) proteins are one of the major pathways in the development of colorectal cancer (CRC). MMR status evaluation is recommended in every new CRC patient. However, this is not fully implemented due to high costs. Tissue microarray (TMA) enables allocating tissue cores from few specimens to a single paraffin block. The primary objective of this study was to evaluate the accuracy of TMA MMR immunohistochemistry (IHC) compared to whole slide. The secondary objective was to evaluate and validate automatic digital image analysis software in differentiating pathological and normal TMA cores.

METHODS

Pathological cores were defined if at least one MMR protein was unstained. Tumoral and normal tissue of 11 CRC patients with known MMR status was used to obtain 623 TMA cores. The MMR staining of each core was evaluated by a pathologist and compared to the whole slide result. Digital analysis software by 3DHistech Ltd. was used to identify cell nucleus and quantify nuclear staining in 323 tissue cores. To identifying pathological tissue, cores the cohort was divided into a test (N = 146 cores) and validation sets (N = 177 cores). A staining intensity score (SIS) was developed, and its performance compared to the pathologist review of each core and to the whole slide result.

RESULTS

Compared to the whole slide, the pathologist's assessment had 100% sensitivity (n/N = 112/112) and 100% specificity (n/N = 278/278) with 95% lower limit of 97 and 99% respectively. The area under the receiver operating characteristic (ROC) curve of SIS was 77%. A cutoff of 55 was obtained from the ROC curve. By implementing the cutoff in the validation dataset, the SIS had sensitivity and specificity of 98.2% [90.1-100%] and 58.5% [49.3-67.4%] respectively.

CONCLUSIONS

The MMR status of CRC can be evaluated in TMA tissue cores thus potentially reducing MMR testing costs. The SIS can be used as triage indicator during pathologic review.

TRIAL REGISTRATION

Institutional ethical approval was granted for the performance of this study (Emek Medical Center Ethics ID: EMC-19-0179).

Clinicopathological significances of P73 and P53 protein expression in gastric carcinomas with tissue microarray technique

AIM: To investigate the expression of P73 and mutant P53 (mP53) gene coding proteins and their significances in gastric carcinoma.

METHODS: Two tissue microarray blocks containing 104 cases of gastric cancer and precancerous lesions (1.0 mm each in diameter) was constructed. SABC immunohistochemical stainning was used to detect the expression of P73 and mP53 proteins and the correlation between their roles and the pathological behavior of gastric carcinoma was investigated.

RESULTS: The positive rate of P73 protein was significantly higher in gastric cancer, intestinal metaplasia and atypical hyperplasia than that in the normal tissues (90.1%, 44.0%, 80.0% vs 17.9%, P < 0.01). The expression of P73 protein was also markedly higher in gastric carcinoma of Borrman Ⅲ/Ⅳ types than that of Borrman Ⅱ type (92.9%/100% vs 57.1%, P < 0.05). Moreover, the expression P73 protein was markedly increased in gastric cancer with lymph node metastasis, liver metastasis and ovarian metastasis as compared with that in non-metastatic cancer (94.4%, 100%, 100% vs 76.2%, P < 0.01). There was a positive correlation between P73 and mP53 expression (χ² = 9.6736, P < 0.01).

CONCLUSION: P73 expression is correlated with the malignant behaviors of gastric cancer. Although P73 protein has a similar construction to P53 protein, its expression shows a positive correlation with that of mP53 protein. This finding indicates that P73 may play a role in the carcinogenesis of gastric cancer as a mimic mutant of P53.