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Immunotherapy in Stage III non-small-cell lung cancer (NSCLC)

癌细胞

In Hong Kong, lung cancer has always been the leading cause of cancer deaths. It is the second most common cancer in Hong Kong. Lung cancer symptoms are not obvious until it progresses to the final stages, which limits options to treatment approach. More recently, there has been growing evidence to show that the use of immunotherapy alongside other conventional treatments can reduce late stage non-small-cell lung cancer (NSCLC) recurrence, improve progression-free survival rates as well as overall survival rates.

Lung cancer is the second most common cancer in Hong Kong. The overall survival rate of lung cancer is less than 15%, making it by far the leading cause of cancer deaths. There are approximately 5,000 newly diagnosed lung cancer cases in Hong Kong every year. Those who smoke as well as those who are chronically exposed to passive (environment) tobacco smoke are at an increased risk of lung cancer. Other risk factors for lung cancer include exposure to asbestos, outdoor air pollution as well as radiation.

There are usually no signs or symptoms in the early stages of lung cancer. Because of this, cases of lung cancer are often diagnosed in the later stages, where the tumours have spread to lymph nodes or other more distant sites. Lung cancer is grouped into two main types: non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). NSCLC makes up about 85% of lung cancers, and can be further categorised into subtypes adenocarcinoma, squamous cell carcinoma and large cell carcinoma. On the other hand, about 15% of lung cancers are SCLC. NSCLC and SCLC are treated differently because SCLC rapidly spreads to other organs much faster than NSCLC. The mainstay treatment modality for SCLC is chemotherapy.

The risk of cancer metastasis is increased in Stage III non-small-cell lung cancer (NSCLC). In general, there is still a chance of cancer recurrence if treated with radical surgery alone. Nowadays, a combination of chemotherapy and radiation therapy are usually the treatment of choice for late stage NSCLC, where the 3-5 year survival rate for patients is reported to be over 20%.

For years, advanced lung cancer has remained as a deadly disease. In recent years, there has been more research dedicated to exploring the role of immunotherapy and treatment for stage III NSCLC. Findings have showed that immunotherapy is indeed effective in controlling PD-L1 expression in tumour cells. In particular, immunotherapy can inhibit T cells (a type of white blood cell as part of the immune system) from attacking the body’s normal and healthy cells.

In clinical practice, immunotherapy is usually only used to treat stage IV lung cancer. However, for the first time, research has shown that the use of immunotherapy in conjunction with conventional radiotherapy and chemotherapy can markedly improve progression-free survival in stage III NSCLC. In particular, findings have concluded the progression-free survival rate to be 5.6 months for patients who were only treated with radiotherapy and/or chemotherapy; whereas the survival rate had increased to 17.2 months for those who received immunotherapy on top of radiotherapy and chemotherapy. These results are considered phenomenal among cancer treatment.

Unlike radiotherapy and chemotherapy, which acts directly on tumours, immunotherapy treatment aims to enhance the body’s own immune system. It functions by activating a stronger than normal immune response to effectively identify and fight cancer cells. For this reason, the side effects of immunotherapy are usually less severe compared to those observed among other cancer treatments. Immunotherapy can be helpful in the treatment of cancers of the lung, colon, liver and skin. All in all, it is anticipated that immunotherapy will continue to revolutionise the treatment of advanced NSCLC.

Dr. Siu Kie Au, clinical oncologist at Hong Kong Integrated Oncology Centre, recalls Mr. Lo, a patient who was diagnosed with stage III NSCLC. Scans revealed that the lung tumour found in this patient to be 12cm wide in diameter, and was additionally spread to the lymph nodes. This meant that Mr. Lo was not a suitable candidate for surgical treatment. Instead, he received a combination of chemotherapy and radiotherapy as part of his cancer treatment. Fortunately, Mr. Lo responded positively to this line of treatment, which was confirmed by Position Emission Tomography (PET) scans and endoscopic procedures. He also received immunotherapy as an adjunct treatment for his cancer. His condition remains stable up until this day.

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