7 PRINT ISSN: 2394-6679 | E-ISSN: 2347-7881 PharmaTutor Magazine | Vol. 3, Issue 3 | magazine.pharmatutor.org Review Article Wonders of Immune System: Spontaneous Regression of Cancers Vishwas B. Chavan Consultant, Sunflower laboratory and diagnostic Center and Clinical Diagnostic Center Mumbai, Maharashtra. vishwaschavan2003@yahoo.co.in Cancer incidence is increasing worldwide [1] . It can affect any part of the body, showing symptoms often in late stages. Diagnosis of cancer has a huge impact on patient and his/her family. Cancer treatments are costly and toxic, many times giving rise to secondary cancers. Even after successful treatment, risk of recurrence of cancer is significant sometimes. However, cancer is not always progressive. It was observed that when an invasive breast cancer is detected in screening, sometimes it regresses spontaneously [2] . There are many tumor-suppressor genes, which prevents a cell from becoming cancerous. There are also some proteins, known as metastasis suppressors, which inhibit metastasis (spread of cancer). This suggests that human immune system can combat cancer and sometimes, can eradicate it completely. CANCER AND IMMUNE SYSTEM Cancer and immune system is linked to each other. In AIDS patients, where immune system fails, incidences of cancers are more. Animal studies have conclusively proved that the immune system can recognize and eliminate malignant tumors. This effect is mediated by cytotoxic T lymphocytes, natural killer cells, macrophages etc. Immune system keeps check on cancer cells by two mechanisms: Cancer immunosurveillance and immunoediting. Cancer immunosurveillance: It is an important host protection process that decreases cancer rates through inhibition of carcinogenesis. In this process, lymphocytes have a central role in recognizing and eliminating continuously arising pre-cancerous cells. Immunoediting: It is a process by which a person is protected from cancer growth and the development of tumor immunogenicity by their immune system. This process contains many steps: 1. Recognition of growing tumor, which is causing local damage. 2. Induction of inflammatory signals for natural killer cells, macrophages etc. 3. Stimulation of infiltrating lymphocytes to produce IFN-gamma. 4. IFN-gamma induces tumor death and production of chemokines (which block the formation of new blood vessels for tumors). 5. Ingestion of tumor cell debris by dendritic cells. 6. Production of IFN-gamma and IL-2 by immune cells (natural killer cells and macrophages) and killing more tumor cells. 7. Tumor-specific T cells move to the tumor site and the cytolytic T lymphocytes then destroy the remaining antigen-bearing tumor cells at the site. However, some tumor cells escape these processes and lead to formation of tumor. Further, cells within a growing tumor acquire How to cite this article: VB Chavan; Wonders of Immune System: Spontaneous Regression of Cancers; PharmaTutor; 2015; 3(3); 7-10