Treatment

Systemic chemotherapy has been extensively used in cancer management including haematological malignancies and solid tumors. In highly chemo-sensitive cancers, such as lymphoma, leukaemia, and germ cell tumors, chemotherapy alone can be curative, whereas in other solid tumors chemotherapy can effectively reduce the chance of recurrence when used in conjunction with surgery or radiotherapy.

In advanced disease setting, chemotherapy often delays disease progression, controls symptom, and improves quality of life.

Cytotoxic agents utilise different mechanism of actions to inhibit cell growth through destruction of DNA, inhibition of nucleic acid synthesis or repair, and inhibition of protein synthesis. They can be classified into 2 main types, cell-cycle specific and cell-cycle non-specific. Common cytotoxic agents include the Antimetabolites (e.g. Gemcitabine, Capecitabine, fluorouracil, Cytarabine), Vinca Alkaloids (e.g. Vincristine), Taxane (e.g. Paclitaxel, Docetaxel), Platinum analogues, and antitumor antibiotics (e.g. Anthracyclines, Bleomycin). These drugs are usually used in combination to maximise cell kill through different mechanisms of action. They can either be administered before or after surgery or radiotherapy. They can sometimes be given concurrent with radiotherapy. Most of these drugs are delivered to the body via intravenous route, but some drugs can be taken orally or even administered into the arteries, pleural cavity or peritoneal cavity, or directly into the surgical bed.

Since cytotoxic agents unselectively inhibit both normal and tumor cells, they do share some common toxicities, in particular to those fast-growing normal cells. General toxicities include bone marrow suppression leading to anemia and increased infection risk, hair loss, and gastrointestinal side effects, such as nausea, vomiting and diarrhoea. Some classes of drug may demonstrate specific class effects, such as nerve toxicity, kidney toxicity, liver toxicity, or heart toxicity. Doctors will closely monitor the toxicity profile of each patient and employ various methods to effectively minimise these side effects.

Our Chemotherapy Day Centre provides a reassuring, private and comfortable environment to patients and their family members during treatment. Every possible assistance is provided by our professional oncology nurses to ensure a smooth and optimal patient journey.

Molecular targeted agents are currently the focus of active cancer research. With better understanding of the molecular mechanisms of tumorogenesis of various cancers, drugs can be developed to interfere with specific molecular targets that are involved in the growth and spread of cancer.

For a specific targeted therapy to work, the corresponding molecular target must be present in the tumor cell, and this is usually verified by tumor biopsy or blood test. The drugs are either in the form of small molecular oral inhibitor or monoclonal antibody given intravenously. They target at different levels of signal transduction pathway that control cell proliferation, cell death, tumor microenvironment, and tumor blood supply. In contrast to chemotherapy which makes no distinction between normal and cancer cells in its attack, targeted therapy causes less damage to normal cells and is therefore associated with less treatment side effects.

Many different targeted therapies have been approved for use either as monotherapy or in combination with chemotherapy. A wide variety of targeted drugs have been approved for the treatment of leukaemia, lymphoma and multiple myeloma. To name a few, chimeric antigen receptor T-cell (CAR-T) therapy genetically modulates autologous T cell to target specific tumor antigen, and is currently used in relapsed leukaemia and lymphoma.

Mabther/Rituximab is a monoclonal antibody commonly used to treat all kinds of B-cell lymphomas. Imatinib is a protein kinase small molecular inhibitor that is effective in treating chronic myeloid leukaemia.

A proportion of lung cancers harbor specific driver mutation, such as the EGFR mutation, ALK rearrangement, ROS1 rearrangement, and BRAF V600E mutation. Specific Tyrosine Kinase Inhibitors, such as Erlotinib, Gefinitib, Afatinib, Decomitinib and Osimertinib are popular drugs used to treat EGFR mutated lung cancers.

Targeted therapy is also widely used in breast cancer. Breast cancer can be classified into three distinct phenotypes: Hormone receptor positive type, HER-2 positive type, and Triple negative type. Cyclin-D kinase 4/6 inhibitors and mTOR inhibitors have been approved for use in combination with hormone therapy to overcome endocrine resistance in hormone receptor positive tumor. Anti-HER2 antibody (Herceptin and Pertuzumab) and HER2 antibody-drug conjugate (TDM-1) are monoclonal antibodies that are effective in HER2 positive disease. Polyadenosine Diphosphoribose Polymerase (PARP) inhibitor (Olaparib) has been approved for use in triple negative breast cancer with germline BRCA mutation.

A number of drugs that inhibit multiple receptor tyrosine kinases have been established as the standard of care treatment in advanced kidney (Cabozantinib, Sunitinib, Pazopanib, Axitinib, Lenvatinib, Sorafenib) and liver cancer (Sorafenib, Lenvatinib, Regorafenib).

Antibody against the vascular endothelial growth factor (VEGF) or VEGF-receptor (VEGFR) has been developed to inhibit vascular growth in tumor. Bevacizumab, an anti-VEGF antibody, has been widely used in colorectal cancer, cervical cancer, glioblastoma (a type of brain tumor), lung cancer, ovarian cancer and kidney cancer. Ramucirumab is an anti-VEGFR antibody that is approved for use in stomach cancer, colorectal cancer, and lung cancer.

Epidermal growth factor receptors (EGFR) are over-expressed in colorectal cancer and head and neck squamous cell carcinoma. Cetuximab and Panitumumab are anti-EGFR antibodies used to treat these types of cancers.

Under normal circumstances, an immune response is triggered when cancer cells are identified by the immune system. However, certain types of cancer may interfere with this mechanism and suppress immune responses, making one prone to cancer attack.

There are several forms of immunotherapy on the market. They can either help the immune system to recognise the cancer, or stimulate the immune system in various ways. Checkpoint inhibitor is a class of drugs (e.g. Pembrolizumab, Nivolumab, Atezolizumab, Durvalumab, Avelumab) that can successfully treat melanoma, kidney cancer, bladder cancer, lymphoma, lung cancer and many other tumour types. It helps the immune system to respond more strongly to a tumor by removing the inhibitory effects of tumor on the immune T-cells.

Hormone therapy, also called endocrine therapy, is a cancer treatment that slows or stops the growth of cancer that is dependent on hormones to grow. Hence, hormone therapy is commonly used to treat breast cancers and prostate cancers. It may be given in different ways, such as the oral route, injection, or surgery to remove the hormone-producing organs (ovaries or testes).

70-80% of breast cancer patients belong to the hormone-receptor positive category. Hormone-receptor positive patients will derive benefits from hormone therapy in the adjuvant setting after breast surgery (Tamoxifen with or without Gonadotrophin releasing hormone analogue for premenopausal patients, and aromatase inhibitors for postmenopausal patients). The duration of hormone therapy in this situation is usually 5 years or longer.

Hormone therapy is also an effective treatment in metastatic hormone-sensitive breast cancer, and provides substantial tumor control with relatively less toxic side effects when compared to systemic chemotherapy. At the time of development of endocrine resistance, further hormone therapy, such as Fulvestrant or Exemestane, may be used alone or in combination with other targeted therapies, such as the Cyclin-dependent kinases 4/6 inhibitors or the mTOR inhibitors, to overcome endocrine resistance.

Almost all prostate cancer cells rely on male sex hormone (androgens) to grow. Androgen deprivation therapy (ADT) can thus effectively suppress prostate cancer by eliminating testosterone production from the testes. In intermediate- to high-risk non-metastatic prostate cancer, ADT can be used before and after radiotherapy to enhance tumor control and reduce tumor recurrence, whereas in metastatic prostate cancer, ADT can be used alone or in combination with chemotherapy to palliate symptom and delay disease progression. ADT can be achieved by surgical removal of testes or regular injection of Luteinizing-releasing hormone analogue.

At the time of acquired endocrine resistance, also called castration resistance, additional hormone therapy, such as antiandrogens or androgen synthesis inhibitors, may be used in combination with ADT to overcome endocrine resistance. Enzulutamide is a new antiandrogen that binds to the androgen receptors of tumor cells to reduce signal transduction and cell proliferation. Abiraterone Acetate is a new androgen synthesis inhibitor that inhibits androgen production from the adrenal glands, tumor cells, and the testes more comprehensively.