Progress, but lung cancer still alarms

In most countries, it ranks third or fourth in terms of cancer occurrence, but is more deadly than the three most common cancers combined (breast, prostate and colon). Lung cancer, like many other cancers, has one main culprit: smoking.
In the US alone, 160,000 people die from lung cancer every year. In Thailand among males, lung cancer is the second-most common cause of cancer after liver cancer and the fourth cause after cervical, breast and liver cancer among females.
The continued prevalence of smoking and poor prognosis of this cancer explain the gloomy mortality figures. In a large survey conducted from 1995 to 2001 in the US, the five-year relative survival rate was 15.7 per cent when considering all stages of lung cancer combined. However, like most cancers, the survival rate largely depends on the stage when it is discovered and varies after 5 years from 2 per cent in most advanced tumours to 49 per cent in early diagnosis of a localised small growth.
The foremost issue regarding lung cancer is its insidious expansion without provoking any symptoms and its ability to disseminate cancerous cells distant from the primary tumour (metastasis). Symptoms often occur when the cancerous mass has already invaded the nearby tissues or infiltrated some lymph nodes surrounding the windpipe or the bronchi.
Symptoms may include a persistent and more severe cough (not easy to notice for the long-time smoker due to existing chronic cough), shortness of breath or wheezing, excessive fatigue with unexpected weight loss and repeated pulmonary infections. More typical symptoms are the coughing of blood (hemoptysis) or chest pain during deep breaths, which may well signify a lung tumour if the patient is a smoker.
A smoker or past smoker who has any of the above-mentioned symptoms should promptly see a medical practitioner. As the clinical signs may appear several years after the start of the cancer, it is possible to diagnose a lung cancer during a check-up from a routine chest X-ray.
Besides the physical exam and some blood tests, the procedure to confirm the presence of lung cancer includes a chest CT scan and the biopsy of the growth. Pathologic analysis of the tumour allows determination of the cancer cellular type and also its genetic features (so-called tumour mutation analysis) that are useful to evaluate the expected efficacy of new molecularly targeted therapy.
Nowadays, specialised lung cancer centres benefit from a minimally invasive technique to collect specimens from the tumour site known as the Endo-Bronchial Ultrasound guided Trans-Bronchial Needle Aspiration (EBUS-TBNA) technique. It is performed under light anaesthesia within a few minutes. It allows the identification of the tumour type and possibly the infiltrated lymph nodes.
The type of cancerous cell is one of the major determinants of treatment options and prognosis. There are two main types of lung cancers based on the dimension characteristics of the abnormal cells, the small cell lung cancer (SCLC) and the non-small cell lung cancer (NSCLC).
The SCLC accounts for 10 per cent of lung cancers and is strongly associated with smoking. It is a fast-developing cancer that quickly spreads to other organs of the body and has the worst prognosis of lung cancers. Due to its aggressive nature, this cancer has only two stages – “limited”, which means still confined to initial tumour location and “extensive”, which means that the cancerous cells have already reached the other lung or other organs.
The “Non-Small” type or NSCLC accounts for 90 per cent of the cases. Because its development is slower than the SCLC, its staging has many grades depending on its expansion upon diagnosis (from 0 to IV).
Overall treatment modalities of lung cancers will be discussed in the next article on October 23.
 

Professor Sawang Saenghirunvattana, is Emeritus Professor of Medicine and Chief of Pulmonary Diseases Centre at Bangkok Hospital. He can be contacted at [email protected].

Dr Gerard Lalande is managing director of CEO-Health, which provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at [email protected].