The Ashcroft scale for the evaluation of bleomycin-induced lung fibrosis is the analysis of stained histological samples by visual assessment. Based on the knowledge that this procedure is not standardized in animals and results are highly variable, we hypothesized that modification of this method may improve quantification of lung fibrosis in small animals. To prove our hypothesis, we evaluated pulmonary fibrosis in Lewis rats induced by a single intratracheal injection of 0.3 mg/kg body weight bleomycin (n = 13) compared with the same amount of saline in a control group (n = 4). We modified the Ashcroft scale by precisely defining the assignment of grades from 0 to 8 for the increasing extent of fibrosis in lung histological samples. Thirty-two observers were randomly assigned to evaluate 108 photographs of slides using either the Ashcroft scale or the modified scale. Consistent with our hypothesis, there was a significant reduction in the variability of standard deviations with the modified scale compared with the Ashcroft scale (mean of variability 0.25 versus 0.62, P < 0.0001). Applying the kappa index, the Ashcroft scale showed only a fair to moderate agreement (0.23-0.59) between the observers and a low intra-observer agreement (0.51-0.74) in contrast to the modified scale, which demonstrated a moderate to good agreement between the observers (0.65-0.93, P < 0.0001) and a high intra-observer agreement (0.87-0.91, P < 0.05). To test the modified scale in vivo, we compared both scales with the results of computed tomography (CT) of the lungs obtained from the same mice. In agreement, the modified scale demonstrated a better correlation to CT scans (R = 0.58) compared with the Ashcroft scale (R = 0.33). In summary, quantification of lung fibrosis in histological lung sections using the modified scale is reliable and reproducible.

Targeting the PD-1/PD-L1 immune checkpoint signaling is a novel promising treatment strategy in several tumor entities, and it is suggested that PD-L1/PD-1 expression is predictive for a PD-1/PD-L1 checkpoint inhibitor treatment response. We investigated the expression of PD-L1 and PD-1 by immunohistochemistry in a large and well characterized gastric cancer (GC) cohort of Caucasian patients, consisting of 465 GC samples and 15 corresponding liver metastases. Staining results were correlated with clinico-pathological characteristics and survival. PD-L1 expression was found in tumor cells of 140 GCs (30.1%) and 9 liver metastases (60%) respectively in immune cells of 411 GCs (88.4%) and 11 liver metastases (73.3%). PD-1 was expressed in tumor infiltrating lymphocytes in 250 GCs (53.8%) and in 11 liver metastases (73.3%). PD-L1 expression was significantly more prevalent in men, GCs of the proximal stomach, unclassified, papillary, Her2/neu-positive, Epstein-Barr-virus-positive, microsatellite instable, and PIK3CA-mutated GCs. A high PD-L1/PD-1 expression was associated with a significantly better patient outcome, and PD-L1 turned out to be an independent survival prognosticator. The correlation of PD-L1/PD-1 expression with distinct clinico-pathological patient characteristics may serve as a surrogate marker of PD-L1-positive GCs and may direct the use of immune checkpoint treatment strategies.

Muir-Torre syndrome (MTS) is an autosomal dominant disease defined by the coincidence of at least one sebaceous skin tumor and one internal malignancy. About half of MTS patients are affected by colorectal cancer. In a subgroup of MTS patients the disease has an underlying DNA mismatch-repair (MMR) defect and thus is allelic to hereditary nonpolyposis colorectal cancer (HNPCC). The purpose of this study was to examine to what extent germ-line mutations in DNA MMR genes are the underlying cause of the MTS phenotype. We ascertained 16 MTS patients with sebaceous skin tumors and colorectal cancer, and we examined their skin and visceral tumors for microsatellite instability. All the patients exhibited high genomic instability in at least one tumor. The search for germ-line mutations in the hMSH2 and hMLH1 genes in 13 of the MTS patients revealed truncating mutations in 9 (69%): eight mutations in the hMSH2 gene and one in the hMLH1 gene. This is the first systematic search for germ-line mutations in patients ascertained on the basis of sebaceous skin tumors. Our results indicate that (1) MTS patients exhibit significantly more mutations in the hMSH2 gene than in the hMLH1 gene; and (2) the subpopulation of MTS patients who are also affected by colorectal cancer, irrespective of family history and age at onset of tumors, may have a likelihood for an underlying DNA MMR defect similar to that for patients with a family history fulfilling the strict clinical criteria for HNPCC.

Microsatellite instable gastric cancer (MSI-GC) is a specific molecular subtype of GC. We studied the phenotypes, genotypes, and clinicopathologic characteristics of MSI-GC in a white GC cohort and compared our findings with an extended literature review. The study cohort consisted of 482 patients. Specimens were available from 452 cases and were used for immunostaining (MLH1, PMS2, MSH2, MSH6) and molecular biological analyses (BAT-25, BAT-26, NR-21, NR-24, NR-27; Epstein-Barr virus in situ hybridization). Thirty-four (7.5%) GCs were MSI. Loss of MLH1 and/or PMS2 was found in 30 (88%) MSI-GC, 3 (9%) showed loss of MSH2 and/or MSH6. One (3%) MSI-GC was identified only by molecular biological testing. A single case was heterogeneous and contained microsatellite-stable and instable tumor areas. Twenty-one (62%) MSI-GCs showed unusual histologic features. MSI-GC was not found in diffuse-type or Epstein-Barr virus-positive GC. MSI-GC was significantly more prevalent in elderly patients, distal stomach, and was associated with a significantly lower number of lymph node metastases and a significantly better overall and tumor-specific survival. MSI-GC constitutes a small but relevant subgroup of GC with distinct clinicopathologic characteristics. Our literature review illustrates the shortcomings of missing standardized testing algorithms with prevalences of MSI-GC ranging from 0% to 44.5%. Future studies should test the hypothesis that patients with MSI-GCs may not need adjuvant/perioperative chemotherapy. However, this will require a standardized, quality-controlled diagnostic algorithm of MSI for GC.