Final answer:
Tumor cells evade the immune system primarily through evading immune recognition and by altering the host immune response, including expressing proteins that inhibit cytotoxic T cells and resistance to apoptosis.
Step-by-step explanation:
How Tumor Cells Evade the Immune System
Tumor cells utilize multiple mechanisms to evade the immune system. One key strategy they employ is evading immune recognition. The immune system normally recognizes and eliminates tumor cells through the process known as immune surveillance, where killer T cells of the adaptive immune system destroy the abnormal cells presenting tumor antigens. However, cancerous cells may alter this response by expressing membrane proteins that inhibit cytotoxic T cells or by promoting the induction of regulatory T cells that suppress the immune response. Additionally, some tumor cells are resistant to apoptosis and thus evade the cell-mediated immune response.
Cancer immunotherapy is a field dedicated to overcoming these challenges by externally stimulating cytotoxic T cells or through therapeutic vaccines that assist or enhance the immune response against cancer. The goal is to effectively target tumor antigens without inducing an autoimmune response, a key challenge for modern medicine.