Oncologist shares how immunotherapy trains your immune system to target and destroy cancer

Unlike chemotherapy, which attacks healthy and cancerous cells alike, immunotherapy retrains the immune system to fight tumours more precisely—with fewer side effects. (Image: Pexels)

Do you ever wonder why some cancers go unnoticed for so long? The answer lies in their ability to hide. It’s because cancer disguises itself from the system meant to protect us. Our immune system constantly scans the body for abnormal cells, but cancer learns how to evade detection—releasing chemicals that weaken immune response or mirroring normal cells to avoid being flagged as threats.

Today, cancer treatment is undergoing a revolution. "Instead of relying solely on chemotherapy or radiation, scientists are now turning inward—teaching the body’s immune system to identify and fight cancer cells on its own. It’s called immunotherapy", Dr Abhishek Raj, Senior Consultant and Head of Medical Oncology, Sarvodaya Hospital, Faridabad told Moneycontrol. By boosting or retraining the immune system, immunotherapy helps the body recognise and destroy tumour cells it once ignored.

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Furthermore, unlike chemotherapy, which damages healthy cells alongside cancerous ones, immunotherapy aims to target only the tumour. “ It minimises collateral damage and sometimes offers longer-lasting effects,” Dr Raj told Moneycontrol. The immune system already knows how to protect us—it just needs help remembering how to act when cancer hides.

Immunotherapy sharpens the immune response, making cancer visible again. “This method is now being used to treat several cancers, including lung, kidney, melanoma, and blood cancers,” he tells, adding, “There are different types of immunotherapy, each using a different mechanism to support the body’s defence system”, he adds.

5 immunotherapy approaches that are saving lives: 

Immune checkpoint inhibitors: These drugs—like nivolumab and pembrolizumab—block proteins (PD-1, PD-L1, CTLA-4) that cancer uses to stop T-cells. As a result immune cells stay switched on and attack tumours aggressively.

CAR-T cell therapy: In a lab, doctors extract T-cells, re-engineer them to target cancer markers, then reintroduce them. This “guided missile” technique is already changing outcomes in leukemias and lymphomas.

Cancer vaccines: These aren’t for prevention—they treat existing cancers by helping the immune system target tumour-specific antigens. A growing frontier in breast and cervical cancers.

Cytokine therapy: Cytokines are messenger proteins that enhance immune activity. They amplify the response, especially in cancers with weak immune visibility.

Monoclonal antibodies: These lab-designed antibodies attach to cancer cells—either marking them for attack or delivering toxic agents right into the tumour's core.

Immunotherapy has become standard care in advanced lung, bladder, kidney cancers, and melanoma. It's now being tested in more curable, early-stage settings. Nevertheless, it's not a miracle. "Not every patient responds," Dr Raj admits. "Biomarkers like PD-L1 are helping us predict who will benefit most. It’s precision medicine, not a one-size-fits-all", Dr Raj tells Moneycontrol.

Risks and side-effects: 

Side effects, though different from chemotherapy, can still be serious. Instead of nausea and hair loss, patients may face immune-related adverse events—rashes, hormone imbalances, even inflammation in the lungs or brain, often delayed. “Over-activation of the immune system can cause it to mistakenly attack healthy organs—leading to issues like inflammation of the liver, lungs, or skin,” shares Dr Raj, adding, “These effects, known as immune-related adverse events, can appear weeks or even months after treatment ends."

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FAQs on Immunotherapy:

Q: What types of cancers can be treated with immunotherapy?
A: Immunotherapy is used to treat several cancers, including lung, kidney, melanoma, and blood cancers.

Q: How does immunotherapy differ from chemotherapy?
A: Unlike chemotherapy, which damages healthy cells alongside cancerous ones, immunotherapy aims to target only the tumour, minimising collateral damage and sometimes offering longer-lasting effects.

Q: What are the side effects of immunotherapy?
A: Side effects can include immune-related adverse events like rashes, hormone imbalances, and inflammation in the lungs or brain. Over-activation of the immune system can also cause it to mistakenly attack healthy organs.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for a specific health diagnosis.