Immunotherapy vs. Chemotherapy: What’s the Difference?

Cancer remains one of the leading causes of death worldwide, but advances in medical science have significantly improved treatment options. Recent clinical research and regulatory milestones have made cancer immunotherapy more accessible, while chemotherapy has been a reliable mainstay since the 1940s. 

Frequently, these treatments are combined or used sequentially to enhance their efficacy. Understanding the distinctions and potential benefits of combining these treatments is crucial for anyone touched by cancer.

Immunotherapy and Chemotherapy: What’s the Difference?

The primary distinction between immunotherapy and chemotherapy lies in how they target cancer cells and their mechanisms of action. 

Immunotherapy doesn’t target cancer cells directly. Instead, it stimulates the immune system to recognize and combat cancer cells more effectively. Several forms of immunotherapy are used today, including checkpoint inhibitors, cancer vaccines, and adoptive cell transfers (ACTs), each with its unique mechanism and application.

Chemotherapy involves administering drugs that are toxic to cells, particularly those that are rapidly dividing, like cancer cells. This can be achieved through various mechanisms, such as interfering with DNA replication or the metabolic processes of cancer cells.

Which Treatment is More Effective, Immunotherapy or Chemotherapy?

Treatment effectiveness varies based on the type of cancer, its stage, and the individual’s specific health condition. Immunotherapy is better suited for targeting specific cancer cells rather than healthy ones, but it can be slower and vary in efficacy. While chemotherapy can quickly shrink tumors, its indiscriminate nature means it can also harm healthy cells, leading to a range of side effects, from nausea and hair loss to more severe complications like immune suppression.

The effectiveness of immunotherapy can vary widely. For instance, the use of programmed death-1 (PD-1) inhibitors has shown a significant response rate in treating melanoma, with some patients experiencing long-term remission. Clinical studies have also demonstrated that immunotherapy can improve survival rates in non-small cell lung cancer patients, with some treatments increasing the five-year survival rate by about 16% compared to traditional therapies.

However, it’s important to note that the effectiveness of immunotherapy in solid tumors is limited. The success of immunotherapy largely depends on the presence of specific markers on tumors and the presence of tumor-targeting immune cells in the tumor microenvironment.

Synergistic Approaches: Combining Immunotherapy and Chemotherapy

Research has shown that combining chemotherapy with immunotherapy can lead to better outcomes than either treatment alone. This combination approach can:

• Enhance the immune system’s ability to fight cancer by exposing more antigens to immune cells.

• Modulate the tumor microenvironment to be more receptive to immune attacks.

Specific examples of the success of this approach include the treatment of metastatic non-small cell lung cancer (NSCLC), where the combination of chemotherapy and PD-L1 inhibitors has significantly increased overall survival rates compared to chemotherapy alone.

Tailoring Treatment to the Patient

The decision to use immunotherapy, chemotherapy, or a combination of both is highly personalized. Factors that influence this decision include:

• Type and Stage of Cancer: Some cancers, like certain skin cancers, are more responsive to immunotherapy, while others respond better to chemotherapy.

• Patient’s Genetic Profile: The presence of specific genetic markers can make some patients better candidates for immunotherapy. 

• Presence of tumor biomarkers: Specific surface protein markers such as PD-L1 and CTLA4 are overexpressed in many types of cancers, making them responsive to anti-PD-L1 and anti-CTLA4 targeted immunotherapy.

At What Stage of Cancer is Immunotherapy Typically Administered?

Immunotherapy can be used at various stages of cancer, but it is particularly effective in the later stages or for cancers that have not responded well to traditional treatments. It’s increasingly being used as part of first-line treatment in cancers like melanoma and lung cancer, where it has shown significant benefits.

At What Stage of Cancer is Chemotherapy Typically Administered?

Chemotherapy is used across all stages of cancer, often as part of a first-line treatment regimen. It effectively reduces tumor size and controls cancer spread in early stages. It can be vital for palliative care in more advanced stages to alleviate symptoms and improve quality of life.

Are Side Effects Worse with Immunotherapy or Chemotherapy?

The severity of side effects from immunotherapy and/or chemotherapy varies and is highly subjective. Chemotherapy often leads to immediate and noticeable side effects, as it affects all rapidly dividing cells. However, immunotherapy tends to cause immune-related side effects ranging from mild to severe. 

Both treatments can result in significant side effects, but their nature and intensity depend on the individual’s health, type of cancer, and treatment specifics.

Chemotherapy Side Effects

Chemotherapy targets all rapidly dividing cells, which includes cancer cells, but unfortunately, it also affects healthy cells in the body’s hair follicles, intestines, and bone marrow. This broad attack can lead to a range of side effects, including: 

• Hair Loss: About 65% of patients undergoing chemotherapy experience alopecia, which can be psychologically distressing.

• Nausea and Vomiting: Over 70% of patients report these symptoms, which can be managed with antiemetic medications.

• Fatigue: One of the most common symptoms, affecting about 80% of patients, is due to anemia or the body’s general response to treatment.

• Increased Infection Risk: As white blood cell count drops, some chemotherapy patients experience some form of infection during their treatment course.

Immunotherapy Side Effects

While generally associated with fewer acute side effects than chemotherapy, immunotherapy can still pose significant risks. Doctors employ several strategies to mitigate immune-related side effects caused by cancer immunotherapy. Common side effects include:

• Immune System Reactions: Since immunotherapy stimulates the immune system, it can sometimes become overactive, leading to inflammation in organs such as the lungs (pneumonitis), colon (colitis), and liver (hepatitis). Corticosteroids are commonly prescribed to suppress an overactive immune response and reduce inflammation. Doctors may taper the dosage over time to minimize long-term side effects.

• Flu-Like Symptoms: Many patients experience fever, chills, and fatigue, which resemble flu symptoms. These symptoms are manageable but can affect daily activities. Antipyretics and analgesics such as acetaminophen and ibuprofen can alleviate fever, muscle pain, or other flu-like symptoms that patients may experience.

• Hormonal Changes: Conditions like hypothyroidism can occur when the immune system affects hormone-producing glands, requiring ongoing hormone replacement therapy. For conditions like hypothyroidism, patients may receive hormone replacement therapy to restore normal levels.

Statistical Insights and Management 

Both chemotherapy and immunotherapy require that patients be well-informed about the potential side effects of their treatment plans and remain aware of when to seek help. This can dramatically improve outcomes and reduce emergency room visits. Patient counseling by care providers, as well as peer-to-peer support among patients, is crucial for navigating the therapy process and providing emotional support to deal with side effects. The prevalence and management of side effects vary:

• For Chemotherapy: Proactive management includes pre-medication with steroids and antiemetics, regular blood tests to monitor cell counts, and the use of growth factors to speed the recovery of bone marrow.

• For Immunotherapy: Close monitoring for signs of immune-related adverse events is essential. Corticosteroids or other immunosuppressants may be employed to manage severe immune reactions.

CRI’s Role in Advancing Cancer Research

As a leader in funding innovative research, CRI supports the development of new immunotherapy treatments and the exploration of their combination with traditional methods like chemotherapy.

With ongoing research and the support of institutions like CRI, the future of cancer treatment is bright, promising more personalized and effective therapeutic options.

Learn more about the latest advancements in cancer treatment and support groundbreaking research. Donate today to help us fund vital research moving us closer to imaging a world immune to cancer.

Updated September, 2024