Cancer treatment has advanced significantly. Chemotherapy and immunotherapy are two prominent methods. This article clarifies whether immunotherapy is considered chemotherapy, addressing a common misunderstanding.
Understanding Chemotherapy
Chemotherapy uses powerful drugs to kill or slow the growth of cancer cells. Used for various cancer types, these drugs interfere with the cell cycle, the process by which cells grow and divide. Cancer cells, which typically divide rapidly and uncontrollably, are particularly susceptible to this disruption.
These drugs attack cells at different points in their lifecycle, hindering their ability to replicate and leading to cell death. For instance, alkylating agents interfere with cancer cell DNA, preventing proper division, while antimetabolites mimic DNA building blocks, disrupting cell division. Because chemotherapy targets rapidly dividing cells, it can also affect healthy cells that divide quickly, such as those in bone marrow, the digestive tract, and hair follicles. This broad impact explains common side effects like nausea, vomiting, hair loss, and fatigue.
Understanding Immunotherapy
Immunotherapy, in contrast, harnesses or modifies the body’s own immune system to fight cancer. It does not directly attack cancer cells but rather stimulates the immune system to recognize and combat them more effectively. The immune system naturally identifies and eliminates foreign invaders and abnormal cells, including some cancer cells. However, cancer cells often develop ways to evade this immune surveillance.
Immunotherapy enhances the immune system’s ability to overcome these evasion strategies. For example, immune checkpoint inhibitors, a type of immunotherapy, block proteins like PD-1 or CTLA-4 that act as “brakes” on immune cells, allowing T cells to mount a stronger attack against cancer. Other forms include cancer vaccines and adoptive cell transfers, which involve modifying a patient’s own immune cells to better target cancer. This approach aims to provide a more targeted and potentially longer-lasting defense against cancer by teaching the immune system to remember and attack cancer cells.
Distinguishing Between Chemotherapy and Immunotherapy
Chemotherapy and immunotherapy are distinct cancer treatments with fundamental differences in their mechanisms and targets. Chemotherapy directly attacks rapidly dividing cells, including cancerous and some healthy cells, using cytotoxic drugs that interfere with cell division. Its primary goal is to kill or slow cancer cell growth by disrupting cellular processes. Side effects often result from this broad targeting of fast-growing cells throughout the body.
Immunotherapy, however, modulates the patient’s immune system to enhance its natural ability to fight cancer. It targets immune cells or pathways to “release the brakes” on the immune response, enabling it to recognize and eliminate cancer cells.
Immunotherapy side effects, known as immune-related adverse events, stem from an overactive or misdirected immune response, potentially causing inflammation in various organs. While chemotherapy often provides immediate tumor shrinkage, immunotherapy’s effects may take longer to manifest as the immune response ramps up, but it can offer more durable responses. Despite their differences, these treatments can sometimes be used together in combination therapies for better outcomes.