What are targeted drugs? Can they treat cancer? Understand their principles, types and effects

In recent years, cancer treatment technologies have continued to advance, with targeted therapy becoming an important treatment option. Unlike traditional chemotherapy, targeted therapy can precisely identify and “attack” specific substances in cancer cells, reducing its impact on normal cells, making treatment more effective and giving cancer patients greater hope. In this article, 10Life will take an in-depth look at the principles, types, effects and side effects of targeted drugs, helping you gain a clearer understanding of targeted cancer drugs.

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

Targeted drugs are mainly divided into small-molecule drugs and monoclonal antibodies. Small-molecule drugs can penetrate cancer cells, interfere with their growth signals or block specific molecules, thereby inhibiting cancer cell activity. Monoclonal antibodies are larger immune system proteins that cannot enter cells, but can identify cancer cells carrying specific proteins. By blocking growth signals or directing the immune system to attack cancer cells, they prevent cancer cells from continuing to divide and grow.

Targeted drugs can be administered orally, by intravenous injection or by subcutaneous injection. However, they are not suitable for all cancer patients. Doctors usually use genetic testing or a biopsy to determine whether the cancer cells carry a suitable receptor (target), and then decide whether this treatment is appropriate.

Cancer cells differ from normal cells because genetic mutations cause them to produce large numbers of abnormal receptors that continuously receive growth signals, causing them to divide uncontrollably and form tumours. In addition to genetic mutations, certain abnormal proteins can also send and receive signals, further promoting the growth of cancer cells. Targeted drugs are designed to act on these receptors (targets), interfering with the growth mechanisms of cancer cells by targeting specific proteins or genetic mutations, preventing them from continuing to proliferate and ultimately causing them to die.

Targeted drugs can be divided into different types, with each type targeting different characteristics of cancer cells.

Signal transduction inhibitors

Cancer cells need to transmit signals in order to grow. These drugs block signalling pathways within cancer cells, preventing them from continuing to divide.

Angiogenesis inhibitors

Tumours need a blood supply to obtain nutrients and grow. Angiogenesis inhibitors can prevent tumours from growing new blood vessels, causing them to gradually shrink due to a lack of nutrients.

Apoptosis-inducing drugs

Healthy cells naturally die when they age or become damaged, a process known as apoptosis. Cancer cells, however, often evade this mechanism. These drugs can activate the apoptosis mechanism in cancer cells, causing them to die naturally.

Immunotherapy drugs

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

Monoclonal antibodies attached to toxins

These drugs deliver toxins or radioactive substances directly into cancer cells, causing them to become damaged or die without affecting normal cells.

Targeted therapy is widely used to treat various cancers, particularly tumours with specific genetic mutations or abnormal proteins. Currently, cancers for which targeted therapy may be suitable include:

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

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

Targeted therapy is not suitable for all cancer patients, and doctors will assess its suitability based on multiple factors. First, different types of cancer have different genetic mutations, so it is necessary to determine whether the cancer cells have an actionable target. To ensure that targeted medicines are suitable for an individual patient, doctors will usually conduct genetic testing to confirm whether the cancer cells have an appropriate target. Secondly, the extent to which the tumour has spread is considered. Targeted therapy is more commonly used for cancers that have spread or cannot be treated with surgery, in order to inhibit tumour growth. In addition, 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 medicines can be used alone or in combination with chemotherapy, radiotherapy or immunotherapy to enhance the overall treatment effect.

The side effects of targeted therapy vary from person to person and are mainly affected by the type of medication and individual constitution. The following are common side effects:

• Gastrointestinal discomfort: nausea, vomiting and diarrhoea; some patients may experience reduced appetite.
• Skin problems: rashes, dryness, acne-like rash, nail changes and loss of hair pigmentation.
• High blood pressure: some targeted drugs affect blood vessel function, causing blood pressure to rise.
• Delayed wound healing: effects on the blood-clotting mechanism may prolong the time required for wounds to heal.
• Effects on the immune system: may cause autoimmune reactions, affecting organs such as the lungs and liver.
• Abnormal liver function: elevated liver enzymes and an increased risk of hepatitis.
• Effects on the heart: may affect cardiac function and increase the risk of arrhythmia or heart failure.
• Gastrointestinal complications: in rare cases, may cause gastrointestinal perforation.

Doctors will adjust the dosage according to the patient’s condition and provide supportive treatment to alleviate side effects. Most side effects will gradually subside after treatment ends. However, as some targeted cancer drugs are relatively new, there may also be potential longer-term effects. Patients should therefore undergo regular check-ups to ensure the safety of their treatment.

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

In Hong Kong, cancer patients experiencing financial difficulties may apply for the Samaritan Fund and the Community Care Fund Medical Assistance Programme to help alleviate the high cost of targeted therapy. However, even with financial assistance, medical expenses remain a heavy burden, and such assistance cannot cover daily living expenses or rehabilitation treatment costs. Purchasing critical illness insurance early can provide financial support in the event of illness, reducing the financial burden and allowing you to focus on treatment with peace of mind. Critical illness insurance involves specialised knowledge, which the general public may not fully understand. When purchasing a policy, you are welcome to consult 10Life licensed insurance advisers for professional advice and to prepare for the future.

Further reading

【Breast Cancer】A comprehensive guide to breast cancer symptoms, types, treatments and prevention
【Critical Illness Insurance Comparison2025】 Which whole life critical illness insurance is the best? Decoding the key features of 5-star insurance
What is the waiting period for critical illness insurance? Key considerations when purchasing critical illness insurance
【Prostate Cancer】Understanding the symptoms, causes, treatments and prevention of prostate cancer

Sources:

• Hong Kong Department of Health. Drug Office. Targeted therapy drugs
• Cancercare.hk Targeted therapy
• Cancer Research UK. What are targeted cancer drugs. 
• The High Cost of Cancer Drugs and What We Can Do About It

本文最後更新日期：2025年4月11日

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.