Heterogeneity of CD8+ tumor-infiltrating lymphocytes in non-small-cell lung cancer: impact on patient prognostic assessments and comparison of quantification by different sampling strategies

Abstract

Introduction Infiltration of non-small-cell lung cancer (NSCLC) by CD8+ T lymphocytes predicts improved patient survival; however, heterogeneity of intratumoral localization complicates this assessment. Strategies for tumor sampling may not accurately represent the whole tumor. We hypothesized that sampling strategies may alter the identification of tumors with high CD8 density and affect the prognostic significance. Patients and methods Twenty-three primary NSCLC tumors were immunohistochemically stained for CD8 and were assessed using automated software with eight different sampling strategies or the whole tumor. Results of all sampling strategies were compared to the whole tumor counts (paired t tests, Pearson’s r). Associations between CD8 densities and overall survival were assessed (log-rank test). Results Counts from all eight sampling strategies significantly correlated with whole tumor counts (p ≤ 0.001). However, the magnitude of CD8+ cell counts and categorization into high vs low infiltrate groups were affected by the sampling strategy. The most concordant values were derived from random sampling of 20 % of the tumor, a simulated core biopsy, or from sampling the tumor center. TIL infiltration was associated with survival when sampling the center (p = 0.038), but not the invasive margin (p > 0.2) or other strategies. Conclusion Different tumor sampling strategies may yield discordant TIL density results and different stratification for risk assessment. Small biopsies may be particularly unrepresentative. Random sampling of larger tumor areas is recommended. Enumerating CD8+ T cells in the tumor center may have prognostic value.

Gene expression analysis in formalin fixed paraffin embedded melanomas is associated with density of corresponding immune cells in those tissues

“…However, a large biopsy of one tumor may be representative of multiple synchronous metastases 40 . Also by modeling different ways to sample a lung cancer, we found that different sampling strategies yield different densities of CD8 + infiltrate, but that the values most concordant with whole tumor counts were predicted by a random core sampling of the tumor or sampling of the tumor center 41 . These studies support our approach of using triplicate or quadruplicate 1 mm diameter cores from each tumor specimen as a reasonable representation of the tumor.…”

Epithelial-mesenchymal transition (EMT) signature is inversely associated with T-cell infiltration in non-small cell lung cancer (NSCLC)

“…As this is a study of an RNA-seq clinical database, our findings need to be validated at the protein level in future studies. Another shortcoming of this study is that TCGA tumor samples are core biopsies or incisional biopsies, which may not be a reliable representative of the entire tumor 46 .…”

Metastatic immune infiltrates correlate with those of the primary tumour in canine osteosarcoma

“…However, variation in immune cell infiltrates within cellular areas is likely to occur throughout the tumour, and the use of tissue archives in this study eliminated our ability to correlate findings with the location of the sample within tumour (ie, center vs invasive margin). Future studies should consider the prospective collection of large portions of tumour from randomly selected sites in order to best represent the tumour as a whole …”

“…Future studies should consider the prospective collection of large portions of tumour from randomly selected sites in order to best represent the tumour as a whole. 61 An important limitation of this study is the selection for cases undergoing a necropsy at the VMTH. This resulted in an overrepresentation of cOSA cases presenting with metastasis at diagnosis, in addition to those experiencing rapid cancer progression since they are more likely to still have a relationship with our hospital.…”