Lung Cancer
05 April 2019
Alarmingly, approximately 1.5 million people die from lung cancer globally each year hence lung cancer remains the number 1 cause of cancer-related deaths worldwide. In Malaysia, lung cancer is the commonest cancer to affect men across all ethnic racial groups and accounts for over 20% of all cancer related deaths. We estimate each year over 3000 Malaysians are newly diagnosed with a lung cancer.
Traditionally, lung cancer has been a disease of men and smokers however in recent years there have been many new cases of lung cancer being diagnosed in non-smokers and females, particularly Oriental (Chinese) women. Broadly speaking there are two main types of lung cancer; Non-small cell lung cancer (NSCLC) which accounts for about 80% of cases and the remaining 20% are cases of small cell lung cancer (SCLC). With rare exceptions, SCLC usually carries a poorer prognosis and is best treated with chemotherapy. In contrast, NSCLC if diagnosed early has a very good prognosis. Prognosis refers to the outcome and for most cancers this measured in terms of a 5-year survival.
NSCLC has four stages namely stages I, II,III and IV (based on the international TNM classification).The stage refers to the extent of spread and will determine both treatment offered and prognosis. Early stage NSCLC (stage I and II) is often best treated with a surgical operation (lung resection) to remove that portion of the lung affected by the tumour (eg. wedge resection, lobectomy or pneumonectomy). The patient may additionally require chemoradiotherapy either before or after the operation to eliminate microscopic disease, reduce recurrence and thus improve survival. The goal of therapy in early stage NSCLC is curative treatment. More advanced NSCLC (stages III and IV) may be amenable to surgical resection in selected cases (if the tumour is still localised to the lung) but often treatment is palliative chemoradiotherapy to improve quality of life only, without any survival benefit, particularly where the cancer has spread elsewhere outside the lungs (metastasis) via the bloodstream or lymph glands.
The diagnosis, staging and subsequent treatment (curative or palliative) of any lung cancer patient may involve several medical specialists including a chest physician, radiologist, pathologist, thoracic surgeon, and oncologist in addition to allied healthcare professionals such as physiotherapists, dieticians and palliative care nurses. Several routine investigations are required to accurately diagnose and stage the disease including chest x-rays, CT scan, PET scan, bronchoscopy, and pulmonary function tests. A sample of tissue (a biopsy) from the affected lung or associated lymph nodes or accompanying fluid (pleural effusion) is essential to confirm the histological diagnosis.
Common symptoms include a persistent cough (> 2 weeks), coughing up blood (haemoptysis), chest wall pain, unexplained weight loss or breathlessness, or recurrent chest infections. Unfortunately many patients may not have any symptoms whatsoever until the tumour is at an advanced stage. 80% of Malaysians newly diagnosed with a NSCLC will have a tumour that is already at an advanced stage (III or IV) when they first see a doctor. Hence screening has been strongly advocated for high risk individuals.
The objective of screening is to detect the disease at a very early stage before it causes any symptoms so as to offer preventive or curative treatment and thus enhance survival. The latest North American guidelines (based on the NLST trial) and ongoing pan-European trials recommend screening for NSCLC with low dose CT scans in adult males with a long history of smoking. Other risk high individuals with a family history of cancer, previous lung infection with tuberculosis or exposure to environmental chemicals/vapours may also benefit from screening. Having said that, screening is not without limitations and a false positive result may cause unnecessary anxiety or lead to unnecessary invasive investigations. It is imperative that if you or a relative, friend or work colleague has either symptoms or high risk features, which you consult with a lung specialist (a chest physician or thoracic surgeon) for careful evaluation and appropriate advice.
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