Dr Vikas Roshan
The Cancer is not a single disease; it is a group of disease. It is one of the commonest cancers and leads to cancer-related deaths all over the world. In India, lung cancer contributes 6.9 per cent of all new cancer cases and 9.3 per cent of all cancer-related deaths in both sexes.
It can start in the windpipe, the main airway (bronchus) or the lung tissue. Lungs are part of the respiratory system. The breathing system is composed of the nose and mouth, trachea, airways to each lung (left and right bronchus) and lungs.
Causes and risk factors
Smoking is associated with 90 % of lung cancer tobacco, and approximately 9 out of 10 lung malignancies are caused by smoking tobacco. This also includes breathing in other people’s smoke called passive smoking.
Even occasional smoking also increases the risk of lung tumour. But your risk increases as duration and no of pack years of smoke increases. The best preventive measure to avoid lung cancer is to stop smoking. The sooner we stop, the better it is.
Other documented substances include asbestos, silica air pollution and fuel exhausts. Asbestos was used in building ships and construction industries in the late 1960s. Smoking, when combined with smoking exposure, leads to increased risk. Silica is a substance used for glass making and bricklaying, and when people who worked with these materials have increased risk of getting lung cancer.COPD is a chronic obstructive pulmonary disease it includes chronic bronchitis and emphysema that lead to chronic damage to the lungs that leads to increased risk of malignancies. Even risk factors increase if a close relative or sibling had lung cancer. The geneticist is working at how the interaction between genes is playing a role in causing Cancer.
Radon gas is a naturally occurring gas that comes from a tiny amount of uranium presents in rocks and soil. It can seep through walls and ground and gets collected in living rooms and upon inhalation can lead to lung cancer.
Investigations to diagnose lung cancer
CT scan In CT scans, we use low energy x rays to scan the lungs and to see inside the body. It helps in the diagnosis and staging and predicting prognosis also. It also helps in response assessment by matching the 3D image.
A bronchoscopy is to look inside the breathing tubes (airways) in the lungs. A pulmonologist can see any areas that look abnormal and take samples (biopsies) to test. This is done with a narrow, flexible tube called a bronchoscope. A doctor can advise this test if your doctor has seen an abnormal-looking area on your lung using an x-ray or CT scan.
An endobronchial ultrasound can show if it’s lung cancer and the size of the tumour. It also shows whether Cancer has spread into other areas of the lung or outside the lung.
Certain Genetic changes in lung cancer make the Cancer grow and divide, such as EGFR-the epidermal growth factor receptor gene, the anaplastic lymphoma kinase (ALK) gene, and he ROS1 gene.
Importance of Stage and grade of Cancer.
The stage of a tumour tells you how big the Cancer is and whether it has spread to nearby structures. The type of Cancer tells the origin of the cell, and the grade depicts how unusual the cells look under the microscope.After knowing the type, stage, and grade of a tumour can help doctors to plan further treatment.The treatment is decided after staging the Cancer and discussing in the multidisciplinary tumour board.
Types of lung cancer
Generally, lung cancers are divided into non-small cell lung cancer and small cell lung cancer. The predominant type being the non-small cell carcinoma. The treatment usually depends upon the type of Cancer.
Lung cancer that starts from the lung is primary lung cancer. Sometimes we see metastatic deposits in lungs from primaries of other organs.
Non-small cell lung cancer (NSCLC) It is a most common type and constitute 80-85%, and there are three main subtypes adenocarcinoma, squamous cell carcinoma and large cell carcinoma. They are classified together as they behave similarly and similarly responds to treatment.
This is the most common type and starts in mucin secreting glands present inlining of airways. They are generally located in peripheries of the lung.Squamous cell cancer develops in the flat cells that cover the airways, and it grows in central locations.
Large cell carcinoma
The cancer cells appear large and round under the microscope.Other types of non-small cell cancer. Some times cancer cells look very undeveloped under the microscope, and pathologist won’t be able to tell exact type of Cancer. Other tests need to be done to get more information.
Treatment for non-small cell lung cancer (NSCLC)Treatment decision generally decided by professionals during multidisciplinary team discussions. Treatment usually depends on the location, stage, grade, age and fitness of the patient. The main treatments available are surgery, chemotherapy, radiotherapy, chemoradiotherapy – chemotherapy with radiotherapy, targeted cancer drugs, immunotherapy, symptom control treatment (Palliative treatment)Generally in Stage 1 in which Cancer is small and contained inside the lung without any spread to lymph nodes needs surgery. Surgery may be in the form lobectomy(part of your lung, complete lung (pneumonectomy)
sometimes physician adds chemotherapy after an operation to lower the chance of your cancer recurrence (coming back.).In case the person is not fit for surgery, radiotherapy can be added. In small tumours even stereotactic body radiotherapy can be planned.
Stage 2 and stage 3 include a heterogenous group which can be divided into different subgroups and further treatment can be planned considering the factors discussed above. There are different combinations and options available for treatment. Possible treatment to be considered
Chemoradiotherapy followed by surgery
Sequential chemotherapy and radiotherapy followed by surgery to remove part or all of the lung.
Surgery followed by chemotherapy.
Immunotherapy after chemoradiotherapy.
Stage IV means that Cancer has disseminated to other lung or to a distant part of the body such as the liver, bones and brain.
Treatment aims to control the Cancer for as long as possible and help with symptoms. Treatment options include chemotherapy, targeted cancer drugs, immunotherapy, radiotherapy, symptom control treatment, such as treatment to help you breathe more easily.
Right now, there is no national screening program for lung cancer in India.
(The author is Senior Consultant Radiation Oncologist)
Dr Vikas Roshan