The advent of immune-checkpoint inhibitors (ICI) in modern oncology has significantly improved survival in several cancer settings. A subgroup of women with breast cancer (BC) has immunogenic infiltration of lymphocytes with expression of programmed death-ligand 1 (PD-L1). These patients may potentially benefit from ICI targeting the programmed death 1 (PD-1)/PD-L1 signaling axis. The use of tumor-infiltrating lymphocytes (TILs) as predictive and prognostic biomarkers has been under intense examination. Emerging data suggest that TILs are associated with response to both cytotoxic treatments and immunotherapy, particularly for patients with triple-negative BC. In this review from The International Immuno-Oncology Biomarker Working Group, we discuss (a) the biological understanding of TILs, (b) their analytical and clinical validity and efforts toward the clinical utility in BC, and (c) the current status of PD-L1 and TIL testing across different continents, including experiences from low-to-middle-income countries, incorporating also the view of a patient advocate. This information will help set the stage for future approaches to optimize the understanding and clinical utilization of TIL analysis in patients with BC.

Prognostication of invasive ampullary adenocarcinomas (AACs) and their stratification into appropriate management categories have been highly challenging owing to a lack of well-established predictive parameters. In colorectal cancers, recent studies have shown that tumor budding confers a worse prognosis and correlates significantly with nodal metastasis and recurrence; however, this has not been evaluated in AAC. To investigate the prevalence, significance, and clinical correlations of tumor budding in AAC, 244 surgically resected, stringently defined, invasive AAC were analyzed for tumor budding—defined as the presence of more than or equal to 5 isolated single cancer cells or clusters composed of fewer than 5 cancer cells per field measuring 0.785 mm2 using a 20 × objective lens in the stroma of the invasive front. The extent of the budding was then further classified as “high” if there were greater than or equal to 3 budding foci and as “low” if there were <3 budding foci or no budding focus. One hundred ninety-four AACs (80%) were found to be high-budding and 50 (20%) were low-budding. When the clinicopathologic features and survival of the 2 groups were compared, the AACs with high-budding had larger invasion size (19 mm vs. 13 mm; P<0.001), an unrecognizable/absent pre-invasive component (57% vs. 82%; P<0.005), infiltrative growth (51% vs. 2%; P<0.001), nonintestinal-type histology (72% vs. 46%; P<0.001), worse differentiation (58% vs. 10%; P<0.001), more lymphatic (74% vs. 10%; P<0.001), and perineural invasion (28% vs. 2%; P<0.001); more lymph node metastasis (44% vs. 17%; P<0.001), higher T-stage (T3 and T4) (42% vs. 10%; P<0.001), and more aggressive behavior (mean survival: 50 mo vs. 32 mo; 3-year and 5-year survival rates: 93% vs. 41% and 68% vs. 24%, respectively; P<0.001). Furthermore, using a multivariable Cox regression model, tumor budding was found to be an independent predictor of survival (P = 0.01), which impacts prognosis (hazard ratio: 2.6) even more than T-stage and lymph node metastasis (hazard ratio: 1.9 and 1.8, respectively). In conclusion, tumor budding is frequently encountered in AAC. High-budding is a strong independent predictor of overall survival, with a prognostic correlation stronger than the 2 established parameters: T-stage and lymph node metastasis. Therefore, budding should be incorporated into surgical pathology reports for AAC.

The expression of different MUC glycoproteins has helped define cellular lineage in variety of pancreatic neoplasms, and has helped identify distinct carcinogenic pathways such as the intestinal pathway characterized by diffuse/strong MUC2/CDX2 expression in intestinal-type intraductal papillary mucinous neoplasms (IPMNs) and their associated colloid carcinomas (CCs). In this study, the expression profile of MUC6, a pyloric-type mucin, was investigated in both preinvasive and invasive pancreatic neoplasia. Florid papillary (“in-situ”) components of 9 intraductal oncocytic papillary neoplasms (IOPNs), 24 IPMNs, and 7 mucinous cystic neoplasms (MCNs), were analyzed immunohistochemically for MUC6 expression, as were 15 PanINs, 112 usual invasive ductal adenocarcinomas (DAs), and 14 CCs. In PanINs, MUC6 expression was limited to the very early areas of PanIN-1A that typically have pyloric features. Expression was lost in later stages. Similarly, in IOPNs or IPMNs or MCNs, MUC6 expression was detectable in the cystic or flat areas that have pyloric-like histology. However, in the more advanced (papillary) components of these neoplasms, MUC6 expression was mostly limited to the “cuboidal-cell” but was not seen in the “columnar-cell” phenotype: there was diffuse or strong expression in 8/9 IOPN and, relatively weaker but consistent expression in all 6/6 pancreatobiliary-type IPMNs; whereas virtually no expression in villous or intestinal-type IPMNs. The 7/8 gastric or foveolar-type IPMNs were also negative; in the single case with positivity, the labeling was limited to high-grade dysplastic areas. Interestingly, the papillae in MCNs were also mostly negative. Among invasive carcinomas, 39/112 DAs and only 1/14CC expressed MUC6. In DA, the expression did not correlate with survival (P=0.94), or any of the markers of aggressiveness: more than 2-cm tumor size (P=0.76), positive surgical margins (P=0.27), lymph node metastasis (P=0.82), or high grade (P=0.08). In conclusion: (1) The expression of MUC6 in oncocytic and pancreatobiliary-type neoplasms but not in villous or intestinal-type neoplasms supports the presence of a pyloropancreatic pathway distinct from the MUC2/CDX2 expressing intestinal pathway in intraductal papillary neoplasia. (2) MUC6 expression is present in the earliest (nonpapillary) form of any type of preinvasive neoplasia regardless of whether it is PanIN or IOPN or IPMN or MCN suggesting that these entities may share some characteristics early on, but evolve along divergent pathways as they progress.

Pancreas cancer exhibits differential expression of ERCC1. High ERCC1 expression is associated with both reduced RFS and OS after resection. ERCC1 expression levels may help to predict patient outcome with adjuvant chemotherapy.

Lymph node status is one of the most important predictors of survival in resectable pancreatic ductal adenocarcinoma; therefore, thorough lymph node evaluation is a critical assessment in pancreatoduodenectomy specimens. There is considerable variability in pancreatoduodenectomy specimens processed histologically. This study compares two approaches of lymph node dissection and evaluation (standard vs orange peeling) of pancreatoduodenectomy specimens. A different approach to dissection of pancreatoduodenectomy specimens was designed to optimize lymph node harvesting: All peripancreatic soft tissues were removed in an orange-peeling manner before further dissection of the pancreatic head. This approach was applied to 52 consecutive pancreatoduodenectomy specimens performed for ductal adenocarcinoma at two institutions. Specimen dissection was otherwise performed routinely. Overall number of lymph nodes harvested, number of positive lymph nodes, and their anatomic distribution were analyzed and compared with cases that had been dissected by the conventional approach. The mean number of lymph nodes identified by the orange-peeling approach was 14.1 (by institution, 13.8 and 14.4), as opposed to 6.1 (by institution, 7 and 5.3) in cases processed by conventional approach (P=0.0001). The number of lymph node-positive cases also increased substantially from 50% (by institution, 54 and 46%) in the conventional method to 73% (by institution, 88 and 58%) in the orange-peeling method (P=0.02). The orange-peeling method of lymph node harvest in pancreatoduodenectomy specimens for ductal adenocarcinoma enhances overall and positive lymph node yield and optimizes ductal adenocarcinoma staging. Therefore, lymph node harvest by the orange-peeling method should be performed routinely before specimen sectioning in assessment of pancreatoduodenectomy for ductal adenocarcinoma.