It is pertinent to discuss lung cancer on the eve of “No Tobacco” month, 31st May being the day of its celebration. Tobacco is well-recognized as a great killer, which kills in many forms right from lung diseases, heart diseases and off-course cancer. Smoked tobacco is the most common form of its use and is the primary cause of Lung cancer accounting for 80-90% of cases. The risk is related to duration as well as intensity of smoking. Passive smoking, cooking fumes, air pollution, diesel fumes, industrial exposure to metals such as chromium and nickel, arsenic, ionizing radiation, asbestos and silica fibers are other causes of lung cancer. Nutritional deficiencies arising from inadequate intake fruits and fresh vegetables have also been implicated.
Lungs are the organ to breathe, and hence the symptoms of lung cancer are pertaining to this function and are as follows:
- Shortness of breath which increases on exertion
- Persistent cough
- Blood in the sputum
- Pain in the chest wall
- Loss of appetite and weight
Akin to breast cancer lung cancer has 4 stages too. Unfortunately, contrary to breast cancer 80% lung cancers are detected in advanced stages and remain incurable. A possible reason for this is, lungs being an internal organ are not amenable to close inspection and secondly lungs have immense reserve, hence by the time symptoms start -lot of damage is done, already. Simply put,
Stage 1 – Lung mass of less than 3 cms and no lymph nodes.
Stage 2 – Mass of more than 3 and less than 7 cms; and/or with bronchial lymph nodes
Stage 3 – Mass of more than 7 cms; and/or with tracheal level lymph nodes.
Stage 4 – Distant spread to bones, liver, brain, kidney and/or any other organ.
Figure – the main wind pipe (trachea) divides into two bronchi which lead to the lungs.
Following investigations are required in a suspected case of lung mass, to confirm diagnosis and staging before treatment is decided.
- CT scan and preferably a PET CT scan of whole body to rule out distant spread.
- Once PET CT confirms it to be a localized disease a tissue biopsy is intended which is done by flexible bronchoscope (Fig 1) or transthoracic route (through the chest wall – Fig 2)
- Tracheal lymph node status is important to know to differentiate stage1 and 2 from 3, as it has treatment implications. Mediastinoscopy (small surgery where a scope is put through the neck in the center of chest wall and multiple lymph node biopsies are done); or a Endobronchial ultrasound guided (wherein a small ultrasound is fixed on the tip of bronchoscope, which helps guiding to abnormal looking areas) lymph node sampling(FNA) is done.
Unfortunately, many early stage lung cancers are missed by wrongly getting labeled as tuberculosis, especially when tissue diagnosis is not performed.
Akin to breast cancer there are many subtypes of lung cancer too and is important to know for choice of therapy.
- Small Cell Type – very aggressive and most chemo-responsive
- Non-small cell Type – further sub typed into squamous cell and adenocarcinoma.
Adenocarcinoma is further sub typed into Mutation present vs. no mutation. There are 2 mutations which are compulsory to test EGFR (epidermal growth factor receptor) and EML4-ALK.
Lung cancer treatments should be taken very seriously.
Stage 1 and 2 lung cancers is amenable to surgery which is offered, if residual lung function after removal of part of the lung will adequately support life. Post surgery, some patients would require chemotherapy which increase cure rates. About 50% patients can get cured in stage 1 and 2.
For stage 3, surgery is not feasible in most, and combined chemotherapy and radiotherapy approach is adopted. When given together can result in, about 20% cure rate. Due to highly complex areas in thorax and overall low tolerance of lung for radiation – high end techniques such as IGRT is done, to avoid radiotherapy to normal lung tissue.
For stage 4 the treatment of choice is chemotherapy alone. And it is here that sub-typing has major role to play, as choice of drugs depend on the subtype. Mutation positive patients are treated with targeted therapies, which have tripled the response rates and survivals, as I have detailed in my article on targeted therapy.
More such breakthrough therapies are awaited in the future, including latest which redirects ones own immunity against cancer, resulting in remarkable and long-lasting responses. However, if an equal effort is made to stop the menace of smoking, we may perhaps need no more breakthroughs to “breathe free of lung cancer”.