The concept that the immune system can recognize and destroy nascent transformed cells was originally embodied in the cancer immunosurveillance hypothesis of Burnet and Thomas. This hypothesis was abandoned shortly afterwards because of the absence of strong experimental evidence supporting the concept. New data, however, clearly show the existence of cancer immunosurveillance and also indicate that it may function as a component of a more general process of cancer immunoediting. This process is responsible for both eliminating tumors and sculpting the immunogenic phenotypes of tumors that eventually form in immunocompetent hosts. In this review, we will summarize the historical and experimental basis of cancer immunoediting and discuss its dual roles in promoting host protection against cancer and facilitating tumor escape from immune destruction.

Cancer immunoediting: from immunosurveillance to tumor escape.

The expression of the human Ki-67 protein is strictly associated with cell proliferation. During interphase, the antigen can be exclusively detected within the nucleus, whereas in mitosis most of the protein is relocated to the surface of the chromosomes. The fact that the Ki-67 protein is present during all active phases of the cell cycle (G(1), S, G(2), and mitosis), but is absent from resting cells (G(0)), makes it an excellent marker for determining the so-called growth fraction of a given cell population. In the first part of this study, the term proliferation marker is discussed and examples of the applications of anti-Ki-67 protein antibodies in diagnostics of human tumors are given. The fraction of Ki-67-positive tumor cells (the Ki-67 labeling index) is often correlated with the clinical course of the disease. The best-studied examples in this context are carcinomas of the prostate and the breast. For these types of tumors, the prognostic value for survival and tumor recurrence has repeatedly been proven in uni- and multivariate analysis. The preparation of new monoclonal antibodies that react with the Ki-67 equivalent protein from rodents now extends the use of the Ki-67 protein as a proliferation marker to laboratory animals that are routinely used in basic research. The second part of this review focuses on the biology of the Ki-67 protein. Our current knowledge of the Ki-67 gene and protein structure, mRNA splicing, expression, and cellular localization during the cell-division cycle is summarized and discussed. Although the Ki-67 protein is well characterized on the molecular level and extensively used as a proliferation marker, the functional significance still remains unclear. There are indications, however, that Ki-67 protein expression is an absolute requirement for progression through the cell-division cycle.

The Ki‐67 protein: From the known and the unknown

Tumours grow within an intricate network of epithelial cells, vascular and lymphatic vessels, cytokines and chemokines, and infiltrating immune cells. Different types of infiltrating immune cells have different effects on tumour progression, which can vary according to cancer type. In this Opinion article we discuss how the context-specific nature of infiltrating immune cells can affect the prognosis of patients.

The immune contexture in human tumours: impact on clinical outcome

Pathology and genetics of tumours of the urinary system and male genital organs

Background Although tumor-infiltrating T cells have been documented in ovarian carcinoma, a clear association with clinical outcome has not been established. Methods We performed immunohistochemical analysis of 186 frozen specimens from advanced-stage ovarian carcinomas to assess the distribution of tumor-infiltrating T cells and conducted outcome analyses. Molecular analyses were performed in some tumors by real-time polymerase chain reaction. Results CD3+ tumor-infiltrating T cells were detected within tumor-cell islets (intratumoral T cells) in 102 of the 186 tumors (54.8 percent); they were undetectable in 72 tumors (38.7 percent); the remaining 12 tumors (6.5 percent) could not be evaluated. There were significant differences in the distributions of progression-free survival and overall survival according to the presence or absence of intratumoral T cells (P<0.001 for both comparisons). The five-year overall survival rate was 38.0 percent among patients whose tumors contained T cells and 4.5 percent ...

http://inmunologia.umh.es/Doctorado/2003NEJMZhangintratumoralTcells%20Maciá.pdf

Intratumoral T cells, recurrence, and survival in epithelial ovarian cancer.

Clinical follow-up data of 276 colorectal adenocarcinoma patients treated in Kuopio University Hospital between 1976 and 1986 and followed up for a mean of 14 years were analysed. The clinical findings were correlated with tumour-infiltrating lymphocytes (TILs) and with histological and quantitative factors including nuclear parameters and volume-corrected mitotic index. In univariate survival analysis, TNM classification, Dukes' stage, histological grade, and TILs were significant predictors of survival. TNM classification, Dukes' stage, and TILs also predicted recurrence-free survival. In multivariate analysis, TILs were an independent prognostic factor of survival in all cases, as well as in patients with T1-4N0-3M0 and T1-4N1-3M1. TILs also independently predicted recurrence-free survival. TILs can provide important prognostic information in colorectal cancer to be used in evaluating for adjuvant therapy in different tumour stages.

Prognostic value of tumour‐infiltrating lymphocytes (TILs) in colorectal cancer

Hyaluronan (HA) is a linear high molecular weight extracellular polysaccharide. It is thought to be involved in mitosis and the enhancement of wound healing, tumor invasion, and metastasis. Because its clinical relevance in cancer has not been explored, we scored HA in colorectal adenocarcinoma and studied its relationship with patient survival. A specific probe prepared from cartilage proteoglycan aggregates was used to stain paraffin-embedded tumor samples from 202 colorectal adenocarcinoma patients treated in Kuopio University Hospital and followed up for a mean of 14 years. The hypothesis that the percentage of HA-positive carcinoma cells (HA%) and HA intensity in cancer cells correlated with survival was tested with the log-rank test, hazard ratios, and their confidence intervals. Ninety-three % of tumors had at least a proportion of carcinoma cells positive for HA. HA intensity in tumor epithelium was stronger in Dukes' stages C and D tumors and in high-grade tumors. The cancer-related survival rate was lower among patients with strong HA intensity in tumor epithelium (P < 0.001) and high HA% (P < 0.001). Recurrence-free survival was also shorter in patients with an intense signal for HA (P = 0.001) and high HA% in tumor epithelium (P = 0.04). HA intensity in tumor epithelium independently predicted survival and recurrence-free survival (Cox's analysis). We conclude that a high proportion of HA-positive cancer cells and high intensity of the HA-signal predicts a poor survival rate. The abnormal expression of HA in the neoplastic colon epithelial cells is suggested to provide a distinct advantage for invasive growth and metastasis.

https://cancerres.aacrjournals.org/content/canres/58/2/342.full.pdf

Tumor Cell-associated Hyaluronan as an Unfavorable Prognostic Factor in Colorectal Cancer

Lymphocyte infiltrates as a prognostic variable in female breast cancer

Histological grade, perineural infiltration, tumour-infiltrating lymphocytes and apoptosis as determinants of long-term prognosis in prostatic adenocarcinoma

Two hundred and twelve archival bladder-cancer biopsy specimens were analyzed immunohistochemically to detect over-expression of p53 protein. The results of immunohistochemical analysis were correlated to established histological and quantitative prognostic factors and survival of patients during a mean follow-up period of more than 10 years. Twentynine percent of tumours were positive for p53 protein, and over-expression was associated with high histological grade, non-papillary growth architecture, dense inflammatory cell reaction, DNA aneuploidy, high S-phase fraction, high mitotic frequency and high SD of nuclear area. Progression in T, N and M categories was significantly related to over-expression of p53 protein. In univariate survival analysis, over-expression of p53 predicted poor outcome in the entire cohort, in papillary tumours and in muscle-invasive tumours but not in superficial tumours. In a multivariate survival analysis, over-expression of p53 oncoprotein had no independent prognostic value over clinical stage and mitotic index. The results confirm that p53 is involved in the growth regulation of bladder cancer and is certainly a subject for detailed analysis of specific mutations.

Pertti Lipponen

Papers

Prognostic value of tumour‐infiltrating lymphocytes (TILs) in colorectal cancer

Tumor Cell-associated Hyaluronan as an Unfavorable Prognostic Factor in Colorectal Cancer

Lymphocyte infiltrates as a prognostic variable in female breast cancer

Histological grade, perineural infiltration, tumour-infiltrating lymphocytes and apoptosis as determinants of long-term prognosis in prostatic adenocarcinoma

Over‐expression of p53 nuclear oncoprotein in transitional‐cell bladder cancer and its prognostic value