Chemotherapy Vs Immunotherapy: Know the Difference

Cancer treatment modalities have evolved significantly over the past decades, offering patients more effective options for their care. Chemotherapy and immunotherapy represent two distinct approaches to fighting cancer, each working in unique ways to target cancer cells. These treatments differ in their methods, side effects, and effectiveness for various types of cancer. Chemotherapy uses powerful and highly potent drugs to kill cancer cells directly, while immunotherapy helps the body's immune system fight cancer cells naturally. Understanding these differences allows patients and oncologists to make informed and correct choices about treatment plans, leading to better outcomes & improved quality of life during treatment.

What Is Immunotherapy?

Immunotherapy is a groundbreaking approach to treat cancer. It harnesses the power of the body's natural defence system. This biological therapy uses substances made from living organisms to treat cancer by enhancing the immune system's ability to fight disease.

The human immune system comprises white blood cells, along with organs and tissues of the lymph system, which work together to protect the body from harmful invaders. Immunotherapy strengthens this natural defence mechanism, helping it better identify and destroy cancer cells.

Medical researchers have developed several types of immunotherapy treatments, each working in unique ways to combat cancer:

• Immune Checkpoint Inhibitors: Drugs that remove restrictions on immune cells, allowing them to respond more aggressively to cancer
• T-cell Transfer Therapy: A treatment that enhances T-cells' natural ability to fight cancer
• Monoclonal Antibodies: Lab-created proteins that mark cancer cells for destruction by the immune system
• Treatment Vaccines: Specialised vaccines that boost the immune response against cancer cells
• Immune System Modulators: Substances that enhance overall immune response

How Does Immunotherapy Work?

At its core, immunotherapy functions through specialised proteins called immune checkpoint proteins, which exist on the surface of T cells. These checkpoint proteins typically bind with partner proteins on other cells, including some cancer cells, creating an "off" signal that prevents the immune system from attacking. Cancer cells often exploit this mechanism to avoid detection and destruction.

Immune checkpoint inhibitors, a crucial type of immunotherapy drug, work by disrupting this process. They block these checkpoint proteins from binding with their partners, removing the "off" signal. This allows T cells to recognise and destroy cancer cells more effectively. Here are the main types of checkpoint inhibitors:

• Drugs that target CTLA-4 checkpoint proteins
• Medications blocking PD-1 proteins or their partner PD-L1
• Combination therapies targeting multiple checkpoints

The effectiveness of immunotherapy relies heavily on the peripheral immune system, which includes immune cells circulating throughout the body. These treatments don't just work locally at the tumour site; they create systemic changes that help the entire immune system better recognise and fight cancer cells. Recent research shows that successful immunotherapy often generates new immune responses rather than reinvigorating existing ones.

When immunotherapy works effectively, it trains the body's immune system to maintain a long-term defence against cancer cells, potentially offering more durable protection than other treatment approaches. This process involves continuous monitoring and adaptation by the immune system, making it a dynamic and personalised form of treatment.

What Is Chemotherapy?

Chemotherapy stands as one of the most established and widely used treatments in the fight against cancer. This powerful treatment employs specialised drugs to target & destroy rapidly dividing cells throughout the body. Unlike localised treatments, chemotherapy works systemically, reaching cancer cells wherever they may be.

Medical oncologists can use chemotherapy in several distinct ways to combat cancer:

• Primary Treatment: Used as the main treatment for certain cancers like leukaemia and lymphoma
• Adjuvant Therapy: Administered after surgery to eliminate remaining cancer cells
• Neoadjuvant Therapy: Given before surgery to shrink tumours
• Palliative Care: Used to control symptoms and improve quality of life

While chemotherapy primarily targets cancer cells, it can also negatively impact healthy body cells that divide quickly, such as those in the skin, hair follicles, and digestive tract. However, normal tissues typically can repair themselves and continue growing, making most side effects temporary.

Treatment delivery varies based on the specific type of cancer and individual patient needs. Chemotherapy can be administered through different routes, including intravenous infusion, oral medications, or injections. The treatment protocol is carefully tailored to each patient, specifying the type of drugs, dosage, frequency, and duration of treatment.

Modern chemotherapy has transformed many once-deadly cancers into treatable conditions. It can significantly improve treatment outcomes when combined with other treatments like surgery or radiation therapy. The decision to use chemotherapy depends on the cancer type, its stage, and the patient's overall health condition.

How Does Chemotherapy Work?

The mechanism behind chemotherapy revolves around disrupting the cell cycle, targeting cells that grow and divide quickly. This treatment works by interfering with cancer cells' DNA and reproduction ability, effectively stopping or slowing their growth.

Different chemotherapy drugs target various phases of the cell cycle. Some medications work specifically during DNA synthesis, while others are effective when cells are actively dividing. For example, drugs like methotrexate and 5-fluorouracil primarily affect cells during DNA replication, while plant alkaloids target cells during the division phase.

Chemotherapy employs several types of drugs, each working through distinct mechanisms:

• Alkylating Agents: Damage DNA directly to prevent cell reproduction
• Antimetabolites: Interfere with DNA and RNA production
• Plant Alkaloids: Stop cells from dividing
• Anti-tumour Antibiotics: Prevent enzymes from synthesising DNA
• Topoisomerase Inhibitors: Interfere with DNA repair

Cancer specialists often combine different chemotherapy drugs to enhance effectiveness. This strategy, known as combination chemotherapy, helps prevent cancer cells from developing resistance and increases the likelihood of destroying cancer cells in various growth phases. For instance, doctors might pair drugs that work in different cell cycle phases, such as combining vincristine with cyclophosphamide.

While chemotherapy primarily targets rapidly dividing cancer cells, it can also affect healthy, rapidly dividing cells such as those in the bone marrow, digestive tract, and hair follicles. However, normal cells typically recover from treatment, while cancer cells often cannot repair the damage caused by chemotherapy, making it an effective treatment option despite its side effects.

Differences Between Immunotherapy and Chemotherapy

While both treatments target cancer cells, the fundamental differences between immunotherapy and chemotherapy lie in their approach to fighting cancer. Understanding these distinctions helps doctors choose each patient's most effective treatment strategy.

The most significant difference lies in how these treatments attack cancer cells. Chemotherapy works directly on cancer cells, targeting all rapidly dividing cells in the body. In contrast, immunotherapy stimulates the body's immune system to recognise and fight cancer cells naturally, making it more selective in its approach.

Key differences between these treatments include:

• Treatment Duration and Effects: Chemotherapy stops working once the drugs are discontinued, while immunotherapy can continue stimulating the immune system even after treatment ends
• Response Time: Chemotherapy typically shows faster initial results in tumour shrinkage, whereas immunotherapy often requires more time to demonstrate effectiveness
• Target Specificity: Chemotherapy affects all rapidly dividing cells, including healthy ones, while immunotherapy specifically targets cancer cells through immune system activation
• Side Effect Profile: Chemotherapy commonly causes hair loss, nausea, and blood cell count changes, while immunotherapy's side effects mainly stem from immune system overactivation
• Cost: Treatment costs also differ substantially between these approaches. Studies indicate that immunotherapy typically carries higher treatment costs than traditional chemotherapy, though actual expenses vary based on specific treatment protocols and duration.

The effectiveness of each treatment varies significantly based on the type and stage of cancer. Recent studies have shown that combining both treatments (chemoimmunotherapy) can be particularly effective for certain cancers, offering better progression-free survival rates than either treatment alone.

Conclusion

Medical science offers both chemotherapy and immunotherapy as powerful weapons against cancer, each bringing unique benefits to cancer treatment. Chemotherapy continues to serve as a reliable option through direct attack on cancer cells, while immunotherapy represents a newer approach that helps the body fight cancer naturally. These treatments show different success rates depending on cancer type, with some patients responding better to one approach over the other. Medical teams now commonly use both treatments together, creating more effective treatment plans for many cancer types.

Treatment choices depend heavily on each patient's specific situation, including cancer type, stage, and overall health condition. Doctors carefully weigh factors like side effects, treatment duration, and cost when deciding between chemotherapy and immunotherapy. Research advances both treatment methods, leading to better outcomes and fewer adverse effects for cancer patients. Doctors now have more tools than ever to create personalised treatment plans that give patients the best chance of recovery.