Targeted Therapy for Cancer: How It Works, Types, Benefits and Side Effects

Cancer treatment has changed significantly with advances in understanding how cancer cells grow and survive. Instead of treating cancers only according to where they develop in the body, doctors can sometimes examine the specific molecular changes driving a tumour.

This has led to an important approach known as targeted therapy for cancer.

Targeted therapies are medicines designed to act on specific proteins, genes or biological processes involved in cancer growth. For selected patients, they can provide a more precise treatment approach based on the characteristics of their cancer.

But how does targeted therapy work, who may benefit from it, and how is it different from chemotherapy?

What Is Targeted Therapy for Cancer?

Targeted therapy is a type of cancer treatment that acts on specific molecular features involved in the growth, survival or spread of cancer cells.

Cancer cells can develop genetic or biological changes that allow them to grow uncontrollably. Some of these changes create potential targets for treatment.

A targeted medicine may be designed to:

• Block signals that tell cancer cells to grow
• Interfere with specific proteins cancer cells depend on
• Prevent the formation of blood vessels that support tumour growth
• Deliver treatment directly to certain cancer cells
• Trigger processes that cause cancer cells to die

Unlike a one-size-fits-all approach, targeted therapy is often selected according to the biological characteristics of an individual’s cancer.

How Does Targeted Therapy Work?

Cancer cells rely on complex biological signals to survive and multiply.

Certain cancers develop abnormal genes or proteins that continuously send signals encouraging cancer growth. If doctors can identify these abnormalities, a medicine may sometimes be used to interfere with them.

The process usually involves three important stages.

Step 1: Identifying the Cancer

Doctors first determine the type and stage of cancer using appropriate diagnostic tests.

Step 2: Biomarker Testing

A tumour sample, blood sample or another specimen may be analysed for specific molecular changes.

Depending on the cancer, doctors may look for biomarkers such as:

• EGFR mutations
• HER2 expression
• ALK rearrangements
• BRAF mutations
• BRCA1 or BRCA2 alterations
• Other clinically relevant molecular changes

Not every cancer requires the same biomarkers.

Step 3: Selecting an Appropriate Treatment

If testing identifies a molecular feature with an established targeted treatment, the oncologist can evaluate whether that medicine is appropriate for the patient.

Finding a target does not automatically mean that a particular treatment will work. Treatment decisions also depend on the cancer stage, previous treatments, overall health and available clinical evidence.

What Are the Main Types of Targeted Cancer Therapy?

Targeted therapies include several different categories of medicines.

1. Small-Molecule Drugs

Small-molecule medicines can enter cells and interfere with proteins involved in cancer growth.

Many targeted cancer medicines belong to this category.

Examples include medicines that inhibit specific tyrosine kinases or other signalling proteins.

These therapies are used in selected cancers where the relevant molecular target is present.

2. Monoclonal Antibodies

Monoclonal antibodies are laboratory-produced proteins designed to recognise particular targets.

Some attach to proteins on cancer cells and interfere with their growth signals. Others may help the immune system recognise cancer cells or deliver another therapeutic substance to a particular target.

Their exact function depends on the antibody and cancer being treated.

3. Angiogenesis Inhibitors

Tumours require a blood supply to receive oxygen and nutrients.

Some targeted medicines interfere with signals involved in the development of new blood vessels, a process called angiogenesis.

By affecting these pathways, treatment may help slow tumour growth in certain cancers.

4. Other Targeted Approaches

Cancer research continues to identify new molecular targets.

Some targeted treatments affect DNA repair mechanisms, hormone-related pathways or other biological processes that cancer cells depend upon.

The appropriate treatment depends on the specific molecular characteristics of the cancer.

Which Cancers Can Be Treated With Targeted Therapy?

Targeted treatments are used in selected patients across many cancer types.

Examples include:

Breast Cancer

HER2-targeted medicines may be used when breast cancer has increased HER2 expression or amplification.

Certain other molecular findings can also influence treatment selection.

Lung Cancer

Non-small cell lung cancer is one of the major examples of biomarker-guided treatment.

Doctors may test for molecular alterations involving genes such as EGFR, ALK, ROS1, BRAF, KRAS and others, depending on the clinical situation.

Colorectal Cancer

Biomarkers such as RAS and BRAF may help guide treatment decisions in certain patients with colorectal cancer.

Prostate Cancer

Specific molecular changes, including selected DNA-repair gene alterations, may help identify targeted treatment options for some patients with advanced prostate cancer.

Blood Cancers

Targeted therapies have transformed the treatment of certain blood cancers.

For example, medicines targeting the BCR::ABL1 protein have played an important role in treating chronic myeloid leukaemia (CML).

Other Cancers

Targeted treatments may also be available for selected patients with melanoma, ovarian cancer, kidney cancer, thyroid cancer, gastrointestinal stromal tumours and several other cancers.

Treatment eligibility depends on the individual cancer and its molecular characteristics.

Why Is Biomarker Testing Important?

Targeted therapy and cancer biomarker testing are closely connected.

Doctors need to know whether a cancer contains the biological target that a particular medicine is designed to affect.

Testing may involve:

• Tumour tissue analysis
• Genetic mutation testing
• Protein testing
• Next-generation sequencing (NGS)
• Liquid biopsy in selected situations

For example, if a treatment is designed to target a particular mutation, using it when that mutation is absent may not provide the intended benefit.

Biomarker testing therefore helps oncologists determine whether particular targeted treatments should be considered.

What Are the Potential Benefits of Targeted Therapy?

For appropriately selected patients, targeted therapy may offer several potential benefits.

More Precise Treatment

The medicine is designed around a specific molecular feature or biological process associated with the cancer.

Personalised Treatment Decisions

Biomarker testing can help doctors select treatments based on characteristics of an individual’s tumour.

Different Treatment Options

Targeted therapy may provide additional options for patients whose cancers contain certain actionable molecular changes.

Combination With Other Treatments

Depending on the cancer, targeted therapy may be used alone or combined with treatments such as:

• Chemotherapy
• Immunotherapy
• Hormone therapy
• Radiation therapy
• Surgery

The treatment strategy depends on the cancer and the available clinical evidence.

What Are the Side Effects of Targeted Therapy?

Although targeted therapies are designed to act on specific biological pathways, they can still affect healthy cells and cause side effects.

Possible side effects vary significantly between medicines but may include:

• Fatigue
• Diarrhoea
• Nausea
• Skin rash
• Changes in appetite
• Mouth sores
• High blood pressure
• Liver-related problems
• Changes in blood cell counts
• Heart-related effects with certain medicines

Different targeted medicines have different safety profiles.

Patients should report new or worsening symptoms to their healthcare team. Doctors may use blood tests, imaging and other assessments to monitor treatment safety.

Targeted Therapy vs Chemotherapy: What’s the Difference?

One of the most common questions patients ask is whether targeted therapy is better than chemotherapy.

The treatments work differently.

Chemotherapy generally attacks rapidly dividing cells. Because some healthy cells also divide rapidly, chemotherapy can affect both cancerous and healthy tissues.

Targeted therapy acts on specific molecular targets or biological pathways associated with cancer.

However, targeted therapy is not automatically safer or more effective.

A patient needs to have a cancer for which an appropriate target and evidence-based treatment exist.

In some situations, chemotherapy and targeted therapy may even be used together.

The right treatment depends on the patient’s individual circumstances.

Can Cancer Become Resistant to Targeted Therapy?

Yes.

Cancer cells can change over time. A targeted medicine that initially controls a cancer may eventually become less effective.

This is known as treatment resistance.

Cancer may develop additional mutations or activate alternative biological pathways that allow it to continue growing despite treatment.

When resistance is suspected, doctors may consider additional investigations.

Depending on the situation, these could include:

• Imaging
• Repeat tissue biopsy
• Liquid biopsy
• Additional biomarker testing

Identifying new molecular changes may sometimes help doctors evaluate another treatment option.

Is Targeted Therapy the Same as Immunotherapy?

No.

Although both are important forms of modern cancer treatment, they generally work differently.

Targeted therapy acts on specific molecular features or biological pathways associated with cancer cells.

Immunotherapy helps the body’s immune system recognise or attack cancer through particular immune mechanisms.

Some patients may receive one approach, while others may receive combinations or sequences of different treatments.

Frequently Asked Questions About Targeted Therapy

Does targeted therapy cure cancer?

Targeted therapy is not a universal cure for cancer.

Some patients can experience significant or long-lasting responses, while others may experience a shorter period of disease control or no meaningful response.

Results depend on the cancer, molecular target, medicine and individual circumstances.

Does every cancer patient qualify for targeted therapy?

No.

Targeted therapy is generally appropriate only when an established treatment exists for a relevant feature of the patient’s cancer.

Do I need genetic testing before targeted therapy?

Some targeted treatments require biomarker or molecular testing before they can be considered.

The exact tests required depend on the cancer and treatment.

Is targeted therapy better than chemotherapy?

Neither treatment is universally better.

For certain molecularly defined cancers, targeted therapy can be highly important. In other situations, chemotherapy, immunotherapy, surgery, radiation or another treatment may be more appropriate.

How long is targeted therapy given?

Treatment duration varies.

Some medicines may continue while the cancer is responding and side effects remain manageable. Others are prescribed for a defined period.

The oncologist determines the appropriate treatment schedule.

Conclusion

Targeted therapy has become an important part of modern cancer care.

By identifying specific genes, proteins and biological pathways involved in cancer growth, doctors can sometimes select treatments designed around the molecular characteristics of an individual patient’s cancer.

However, targeted therapy is not suitable for every patient. Biomarker testing, accurate diagnosis and careful medical assessment are essential when determining whether a particular treatment should be considered.

At Galaxy Super Speciality, we aim to provide clear and reliable information that helps patients and families better understand developments in cancer treatment.

Always consult a qualified oncologist before making decisions about cancer testing or treatment.

Medical Disclaimer: This article is intended for general educational purposes only and does not replace professional medical advice, diagnosis or treatment.

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Targeted Therapy for Cancer: Types, Benefits & Side Effects

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