What are targeted drugs? Can they treat cancer? Learn about their principles, types, and effects.

In recent years, cancer treatment technologies have continuously advanced, with targeted therapy becoming a significant approach. Unlike traditional chemotherapy, targeted therapy precisely targets specific substances in cancer cells for "attack", minimising the impact on normal cells. This makes the treatment more effective and brings greater hope to cancer patients. In this article, 10Life will provide an in-depth analysis of the principles, types, effects, and side effects of targeted drugs, helping everyone gain a clearer understanding of cancer targeted therapies.

Targeted Therapy is a treatment method that focuses on specific molecules in cancer cells. Compared to traditional chemotherapy, targeted drugs can more precisely inhibit and destroy cancer cells while having a lesser impact on normal cells, resulting in relatively milder side effects.

Targeted drugs are mainly divided into small molecule drugs and monoclonal antibodies. Small molecule drugs can penetrate inside cancer cells, interfering with their growth signals or blocking specific molecules, thereby inhibiting cancer cell activity. Monoclonal antibodies, on the other hand, are larger immune system proteins that cannot enter cells but can mark cancer cells with specific proteins. By blocking growth signals or guiding the immune system to attack cancer cells, they prevent cancer cells from continuing to divide and grow.

The administration of targeted drugs includes oral intake, intravenous injection, or subcutaneous injection. However, not all cancer patients are suitable for this treatment. Doctors typically conduct genetic testing or biopsies to confirm whether the cancer cells have usable receptors (targets) before deciding if this treatment method is appropriate.

Cancer cells differ from normal cells due to genetic mutations that result in a large number of abnormal receptors, continuously receiving growth signals, causing uncontrolled division and the formation of tumours. In addition to genetic mutations, certain abnormal proteins also send and receive signals, further promoting cancer cell growth. Targeted therapies are designed to address these receptors (targets) by locking onto specific proteins or genetic mutations, interfering with the growth mechanisms of cancer cells, preventing their proliferation, and ultimately leading to their death.

Targeted drugs can be divided into different types, each designed to address specific characteristics of cancer cells.

Signal Transduction Inhibitors

The growth of cancer cells relies on signal transmission. These drugs block the signalling pathways within cancer cells, preventing them from dividing further.

Angiogenesis Inhibitors

Tumours require blood vessels to supply nutrients for growth. Angiogenesis inhibitors prevent the formation of new blood vessels in tumours, depriving them of nutrients and causing them to shrink over time.

Apoptosis-Inducing Drugs

Healthy cells naturally die when they age or become damaged (a process called apoptosis), but cancer cells often evade this mechanism. These drugs activate the apoptosis mechanism in cancer cells, causing them to self-destruct.

Immunotherapy Drugs

Some cancer cells can hide themselves to avoid detection by the immune system. Certain immune-targeted drugs help immune cells recognise and attack cancer cells.

Toxin-Conjugated Monoclonal Antibodies

These drugs deliver toxins or radioactive substances directly into cancer cells, damaging or killing them without affecting normal cells.

Targeted therapy has been widely used in the treatment of various cancers, particularly for tumours with specific genetic mutations or abnormal proteins. Currently, cancers that can be treated with targeted therapy include:

• Lung cancer
• Breast cancer
• Colorectal cancer
• Liver cancer
• Kidney cancer
• Prostate cancer
• Blood cancers (such as leukaemia, multiple myeloma, lymphoma)
• Brain cancer (such as glioblastoma)
• Digestive system cancers (such as oesophageal cancer, gastric cancer, pancreatic cancer, bile duct cancer)
• Head and neck cancers (such as nasopharyngeal cancer, laryngeal cancer, oral cancer)
• Skin cancer (such as melanoma)
• Thyroid cancer
• Bladder cancer

The targeted drugs used vary depending on the type of cancer. Doctors will assess whether targeted therapy is suitable based on genetic testing results and develop an appropriate treatment plan.

Targeted therapy is not suitable for all cancer patients, and doctors will evaluate based on multiple factors. Firstly, different types of cancer have distinct genetic mutations, and it is necessary to confirm whether the cancer cells possess targetable markers. To ensure that targeted drugs are appropriate for individual patients, doctors typically conduct genetic testing to verify if the cancer cells have suitable targets. Secondly, the extent of tumour spread is considered; targeted therapy is more commonly used for cancers that have spread or are inoperable, to suppress tumour growth. Additionally, if a patient responds poorly to chemotherapy or radiotherapy, the doctor may consider switching to targeted therapy or combining it with other treatment methods. 

Targeted drugs can be used alone or in combination with chemotherapy, radiotherapy, or immunotherapy to enhance the overall treatment effectiveness.

The side effects of targeted therapy vary from person to person and are mainly influenced by the type of drug and individual constitution. Below are some common side effects:

• Gastrointestinal discomfort: nausea, vomiting, diarrhoea, and some patients may experience a loss of appetite.
• Skin issues: rashes, dryness, acne-like rashes, nail changes, and hair depigmentation.
• High blood pressure: some targeted drugs affect vascular function, leading to elevated blood pressure.
• Delayed wound healing: affects the clotting mechanism, prolonging wound recovery time.
• Immune system effects: may trigger autoimmune reactions, impacting organs such as the lungs and liver.
• Liver function abnormalities: elevated liver enzymes and increased risk of hepatitis.
• Cardiac effects: may impact heart function, increasing the risk of arrhythmias or heart failure.
• Gastrointestinal complications: in rare cases, may lead to gastrointestinal perforation.

Doctors will adjust the drug dosage based on the patient's condition and provide supportive treatments to alleviate side effects. Most side effects will gradually subside after the treatment ends, but since some cancer-targeted drugs are relatively new, there may also be potential longer-term effects. Therefore, patients should undergo regular check-ups to ensure the safety of the treatment.

The price of targeted therapy drugs is usually influenced by various factors, including the patient's weight, dosage requirements, treatment frequency, and the type of drug. Below are the targeted therapy drugs for different types of cancer and their monthly reference costs:

In Hong Kong, cancer patients facing financial difficulties can apply for the Samaritan Fund and the Community Care Fund Medical Assistance Programmes to alleviate the high costs of targeted therapy. However, even with subsidies, medical expenses remain substantial, and they do not cover daily living expenses or rehabilitation costs. Purchasing critical illness insurance early can provide financial support during illness, reducing economic burdens and allowing peace of mind during treatment. Critical illness insurance involves specialised knowledge that the general public may not fully understand. When purchasing a policy, you are welcome to consult10Life licensed insurance advisors for professional advice to prepare for the future.

Further Reading

【Breast Cancer】A Comprehensive Guide to Symptoms, Types, Treatments, and Prevention Methods
【Critical Illness Insurance Comparison 2025】Which Whole Life Critical Illness Insurance is the Best? Key Insights into 5-Star Policies
What is the Waiting Period for Critical Illness Insurance? Key Considerations When Purchasing Critical Illness Insurance
【Prostate Cancer】Understanding Symptoms, Causes, Treatments, and Prevention Methods for Prostate Cancer

Sources:

• Department of Health, Hong Kong. Drug Office.Targeted Therapy Drugs
• Cancercare.hkTargeted Therapy
• Cancer Research UK.What are Targeted Cancer Drugs. 
• The High Cost of Cancer Drugs and What We Can Do About It

Last updated: 11 April 2025

This English version of this article has been generated by machine translation powered by AI. It is provided solely for reference purposes. In the event of any discrepancy or inconsistency between this translation and the original Chinese version, the Chinese version shall prevail.