According to the GLOBOCAN 2012 report, lung cancer is the fourth commonest cause of cancer in India with an estimated incidence of 70,275 in all ages and both sexes. However, it is largely diagnosed in advanced stages making it the third most common cause of cancer-related mortality in India after breast and cervical cancer.

Risk Factors of lung cancer

Smoking – Lung cancer is 13 times more likely to happen in current smokers and 4 times more likely in former smokers as compared to the general population. Prolonged passive adult home exposure to smoking also tends to increase lung cancer risk.

Occupational or environmental exposure to chemicals like radon, arsenic, asbestos and radioactive materials.
Air pollution especially diesel exhaust
Personal or family history of lung cancer

Early warning signs of lung cancer:

The lungs have fewer nerve-endings compared to most other parts of the body, and hence, lung cancer normally does not present with symptoms unless it is in an advanced stage.

However, the following signs and symptoms must be evaluated by an expert physician at the earliest.
A cough that is persistent or worsening, or a change in a chronic cough
Blood in your sputum when you cough
Pain in the back, chest or shoulders when you cough, laugh or take a deep breath
Shortness of breath that occurs suddenly or during daily activities.
Feeling tired or lethargic
Loss of appetite
Unexplained significant weight loss (>10% in three months)

Other uncommon symptoms of lung cancer include:

Difficulty in swallowing
Swelling and puffiness of your face and neck
Changes in the appearance of your fingers, known as clubbing.
Recurrent or persistent infections, such as bronchitis or pneumonia

Although most symptoms can be caused by more common and less threatening ailments like tuberculosis, it is important to see a doctor to rule out lung cancer. An early diagnosis enables you to achieve complete cure of cancer with appropriate treatment.

Advanced lung cancer signs and symptoms

Advanced stages of lung cancer are usually characterized by the spread of cancer to different parts of the body, such as the bones, liver or brain. The symptoms in advanced stages depend on the organs involved:

Neurological symptoms: These manifest when cancer has spread to the brain. Symptoms include headache, dizziness, projective vomiting or seizures. Numbness or weakness of limbs can be seen when a tumour is seen compressing a nerve or nerve bundle.
Liver related symptoms: Jaundice, itching, fatigue, and nausea may be present. In later stages, the altered behaviour pattern with confusion may be caused.
Skeletal symptoms: Bone pain commonly affecting the ribs or vertebrae and pathological fractures may happen if the disease has spread to the bones.
Lumps: Cancer may spread throughout the lymph nodes in advanced stages which present right beneath the skin may present as lumps when enlarged.
Horner Syndrome: This is seen in a few advanced cases of lung cancer. The tumour, when present in the upper lobe of the lung, may grow to be large enough to cause compression of the nerve or nerves that supply the face. This affects the motor functions of the face and causes drooping of the eyelid and constriction of the pupil on the affected side.
Paraneoplastic syndrome: Cancer cells in the system may trigger the body to produce various chemicals in response. These, in turn, cause symptoms, which is referred to as a paraneoplastic syndrome. Symptoms such as hypercalcemia, excess blood clots or bone growth may be seen. Syndrome of Inappropriate Antidiuretic Hormone (SIADH),

Cushing Syndrome and Lambert-Eaton Syndrome may occur rarely especially in patients with small-cell lung cancer.