Mismatch Repair Protein Loss as a Prognostic and Predictive Biomarker in Breast Cancers Regardless of Microsatellite Instability

Determination of Mismatch Repair Status in Human Cancer and Its Clinical Significance: Does One Size Fit All?

The clinical management of cancers has progressed rapidly into the immunopathology era, with the unprecedented histology-agnostic approval of pembrolizumab in mismatch repair (MMR) deficient tumors. Despite the significant recent achievements in the treatment of these patients, however, the identification of clinically relevant subclasses of cancers based on the MMR status remains a major challenge. Many investigations have assessed the role of different diagnostic tools, including immunohistochemistry, microsatellite instability, and tumor mutational burden in both prognostic and therapeutic settings, with heterogenous results. To date, there are no tumor-specific guidelines or companion diagnostic tests for MMR assessment, and this analysis is often performed with locally developed methods. In this review, we provide a comprehensive overview of the current state-of-knowledge of MMR alterations in syndromic and sporadic tumors and discuss the available armamentarium for MMR pathologic characterization, from morphology to high-throughput molecular tools.

A novel integrated platform for the identification of surgical margins in oral squamous cell carcinoma: results from a prospective single-institution series

BACKGROUND

The optimal surgical margins assessment is capital in oral squamous cell carcinoma (OSCC) management. We evaluated the clinical benefits of integrating intraoperative macroscopic margin (MM) assessment and narrow band imaging (NBI).

METHODS

Sixteen OSCC patients eligible for surgery were prospectively enrolled. For each patient, 2 to 6 bioptic samples of MM and NBI margins were obtained and histologically analyzed for the presence of dysplasia and lymphocytes. Microvessel density was investigated by CD34 immunohistochemistry.

RESULTS

Taken together, 104 specimens were analyzed, including 15% tumors, 33% MM, 33% NBI margins, and 19% MM-NBI overlapping margins. The NBI margins were closer to the lesion in 50% cases, while the same number of MM were more conservative than NBI, irrespective of the tumor site. The rate of histologically positive margins was similar among the two methods, akin to the microvessel density.

CONCLUSIONS

MM assessment should be integrated but not replaced with the NBI technology to allow for more conservative surgery.

Molecular Insights into the Classification of Luminal Breast Cancers: The Genomic Heterogeneity of Progesterone-Negative Tumors

Estrogen receptor (ER)-positive progesterone receptor (PR)-negative breast cancers are infrequent but clinically challenging. Despite the volume of genomic data available on these tumors, their biology remains poorly understood. Here, we aimed to identify clinically relevant subclasses of ER+/PR- breast cancers based on their mutational landscape. The Cancer Genomics Data Server was interrogated for mutational and clinical data of all ER+ breast cancers with information on PR status from The Cancer Genome Atlas (TCGA), Memorial Sloan Kettering (MSK), and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) projects. Clustering analysis was performed using gplots, ggplot2, and ComplexHeatmap packages. Comparisons between groups were performed using the Student's t-test and the test of Equal or Given Proportions. Survival curves were built according to the Kaplan⁻Meier method; differences in survival were assessed with the log-rank test. A total of 3570 ER+ breast cancers (PR- n = 959, 27%; PR+ n = 2611, 73%) were analyzed. Mutations in well-known cancer genes such as TP53, GATA3, CDH1, HER2, CDH1, and BRAF were private to or enriched for in PR- tumors. Mutual exclusivity analysis revealed the presence of four molecular clusters with significantly different prognosis on the basis of PIK3CA and TP53 status. ER+/PR- breast cancers are genetically heterogeneous and encompass a variety of distinct entities in terms of prognostic and predictive information.

Breast Cancer Systemic Treatments and Upper Limb Lymphedema: A Risk-Assessment Platform Encompassing Tumor-Specific Pathological Features Reveals the Potential Role of Trastuzumab

Breast cancer related lymphedema (BCRL) is frequent but strategies for an individualized risk assessment are lacking. We aimed to define whether tumor-specific pathological features, coupled with clinical and therapeutic data, could help identify patients at risk. Data from 368 patients with node-positive breast cancers were retrospectively collected, including 75 patients with BCRL (0.4⁻25.6 years follow-up). BCRL was assessed during the standard follow-up oncology visits using the circumferential measurement. Clinicopathologic and therapeutic factors associated with BCRL were integrated into a Cox proportional hazards regression model. Lymphovascular invasion (LVI) was more common in BCRL patients (n = 33, 44% vs. n = 85, 29%, p = 0.01), akin extra nodal extension (ENE) of the metastasis (n = 57, 76% vs. n = 180, 61%, p = 0.02). Sentinel lymph node excision without axillary dissection and extra-axillary radiotherapy were BCRL-unrelated. A higher number of BCRL-positive patients were treated with taxane-based chemotherapy with or without trastuzumab, compared to BCRL-negative patients (p < 0.01). Treatment with trastuzumab and/or taxanes, adjusted for systemic infections, laterality, therapy, and pathological features (i.e., LVI and ENE), had a significant impact in BCRL-free survival (p < 0.01). This work offers new insights on BCRL risk stratification, where the integration of clinical, therapeutic, and tumor-specific pathological data suggests a possible role of anti-human epidermal growth factor receptor 2 (HER2) therapy in BCRL pathogenesis.