J Cancer 2013; 4(1):84-95. doi:10.7150/jca.5482 This issue
1. Diagnostic and Translational Research Center, Henry Jackson Foundation, Gaithersburg, MD, USA;
2. College of Animal Science and Veterinary Medicine, Jilin University, Changchun, Jilin, China;
3. Surgical Oncology, Walter Reed National Military Medical Center, and Uniformed Services University of the Health Sciences, Bethesda, MD, USA;
4. Veterans Affair Medical Center, Washington, DC, USA;
5. Bon Secours National Cancer Institute (BSNCI), Richmond VA, USA;
6. John Wayne Cancer Institute; California Oncology Research Institute; and, David Geffen School of Medicine, University of California, Los Angeles, USA;
7. Theodor-Billroth-Academy®, Munich, Germany;
8. Clinic of Abdominal, Endocrine, and Transplantation Surgery, Clinical Center of Vojvodina, University of Novi Sad - Medical Faculty, Novi Sad, Serbia;
9. The Surgical Oncology Laboratory, Department of Surgery, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel;
10. Division of Oral Biology and Medicine, Jonsson Comprehensive Cancer Center, UCLA School of Dentistry, Los Angeles, CA, USA.
It is a commonly held belief that infiltration of immune cells into tumor tissues and direct physical contact between tumor cells and infiltrated immune cells is associated with physical destructions of the tumor cells, reduction of the tumor burden, and improved clinical prognosis. An increasing number of studies, however, have suggested that aberrant infiltration of immune cells into tumor or normal tissues may promote tumor progression, invasion, and metastasis. Neither the primary reason for these contradictory observations, nor the mechanism for the reported diverse impact of tumor-infiltrating immune cells has been elucidated, making it difficult to judge the clinical implications of infiltration of immune cells within tumor tissues. This mini-review presents several existing hypotheses and models that favor the promoting impact of tumor-infiltrating immune cells on tumor invasion and metastasis, and also analyzes their strength and weakness.
Keywords: immune cell, tumor progression, invasion, metastasis