Lung cancer

Lung cancer

Smoking and lung cancer

Smoking is the single most important cause of lung cancers. Out of every 100 people who develop lung cancer 80-90 will have a history of smoking. The risk of developing lung cancer in smokers is calculated in terms of pack years. The number of pack of cigarettes smoked every day is the number of pack years which is multiplied by the number of years the people has smoked. The more the number of packs and more the number of years higher will be the chances of getting cancer. There are more than 4000 identified carcinogens in cigarette smoke. The most important being benzene and poly aromatic hydrocarbons. Cessation of smoking does bring down the chances of cancer but not to zero. Passive smoking also can lead onto cancer.

Apart from smoking the other risk factor would be atmospheric pollution which may be either due to vehicles or industrial pollution.

Signs and symptoms

In about 10 % patients lung cancer can be incidentally detected without any symptoms

1. Respiratory symptoms - coughing, blood in sputum, wheezing
2. Systemic symptoms - loss of weight , loss of appetite

Symptoms due to cancer pressing on nearby structures- chest wall pain, difficulty in swallowing, swelling of the face.

Some patients presently directly with symptoms of metastases to the brain like headache, giddiness.

Lung cancer sometimes produces symptoms which cannot directly be attributed to the primary cancer of the metastases. These symptoms like muscle weakness, skin changes etc are termed paraneoplastic syndromes.

Diagnosis

The initial test performed in lung cancer is a chest x ray Subsequent to this the following tests may be performed

● CT scan of the chest
● PET CT scan
● Bronchoscopy

A CT scan guided biopsy may be required for confirmation of the diagnosis.

The biopsy is sent for various tests known as molecular markers which helps decide about appropriate treatment.

Types of lung cancer

Lung cancer is classified into two types :

1. Non small cell lung cancer
2. Small cell lung cancer

Non small cell lung cancer is further divided to adenocarcinoma, squamous carcinoma and large cell cancer

In recent times lung cancer is classified more on their expression of molecular markers apart from the stage as this impacts the treatment

Treatment of lung cancer:

Treatment of lung cancer will depend on the stage of the disease

In early stages stage 1 and 2 where in the tumour is confined to a part of the lung , that portion of the lung is removed. This procedure is called lobectomy. The surrounding lymph nodes are removed for accurate staging of the disease. Rarely removal of the entire lung may be required- a procedure known as pneumonectomy.

These types of surgeries are now done by minimally invasive methods either by thoracoscopy or robotic method. This avoids a long incision and pain associated with it.

When the tumour is no longer confined to the lung and has spread to the lymph nodes the initial treatment would be chemotherapy along with or followed by radiation. Depending on the response subsequently surgery may be advised.

Cancer which has spread to far off areas cannot be cured and treated with palliative intent. The usual treatment of these cancers is chemotherapy.

Survival figures for lung cancers are not very good. While there is a 70% chance of cure in stage 1 it drops down drastically in the subsequent stages and is less than 5 % in stage 4.

With the limitations of treatment options for lung cancer the main weapon remains awareness about the harmful effect of smoking and prevention of lung cancer. A combination of public awareness about smoking combined with government legislation can go a long way in keeping this deadly disease under check.