Thoracic cancers are a group of malignancies that affect the organs and structures within the chest cavity, or thorax. This category primarily includes lung cancer, which is by far the most common and deadliest of the group, and a less common group of tumours known as mediastinal tumours. The mediastinum is the central compartment of the chest, located between the lungs, and contains vital organs like the heart, oesophagus, and thymus.

• Lung cancer arises from the cells lining the airways in the lungs. It is broadly classified into two main types:

• Non-small cell lung cancer (NSCLC): The most common type, accounting for about 85% of all lung cancers.

• Small cell lung cancer (SCLC): A more aggressive type that is almost exclusively found in heavy smokers.

• Mediastinal tumours are growths that can be either benign or malignant and arise from any of the tissues within the mediastinum. The most common types include lymphomas, thymomas, and neurogenic tumours.

Risk factors for thoracic cancers are often related to lifestyle and environmental exposures.

• Tobacco Smoke: This is the single most significant risk factor for lung cancer, causing about 80% of all cases. This includes smoking cigarettes, bidis, cigars, and pipes. The risk increases with the duration and intensity of smoking.

• Second-hand Smoke: Inhaling the smoke of others also significantly increases the risk of lung cancer. In India, passive smoking, especially in homes and public spaces, is a major concern.

• Air Pollution: Exposure to both indoor and outdoor air pollution is an important and rising risk factor for lung cancer, particularly in non-smokers. This includes pollutants from industrial sources, vehicle exhaust, and the combustion of household solid fuels.

• Occupational and Environmental Exposures: Exposure to certain substances in the workplace, such as asbestos, radon gas, arsenic, and chromium, can increase the risk of lung cancer.

• Genetics and Family History: A personal or family history of lung or other cancers can increase risk. Certain genetic syndromes may also predispose an individual to developing mediastinal tumours.

In India, the epidemiology of thoracic cancers, particularly lung cancer, shows some distinct patterns.

• Rising Incidence: Lung cancer is a major public health concern in India, with the number of cases and deaths projected to rise significantly. It is one of the most common cancers among Indian men.

• Age of Onset: A notable trend in India is that lung cancer is often diagnosed in a younger age group compared to Western populations. The median age of diagnosis is a decade younger, which may be linked to early and intense tobacco use.

• Gender Disparity: While lung cancer is more common in men due to higher rates of smoking, the incidence is also rising among women. This is often attributed to a combination of passive smoking and exposure to indoor air pollution, particularly from cooking fuels.

• Geographic Variation: The burden of lung cancer is not uniform across India. The Northeast region has some of the highest incidence rates, which are often linked to specific traditional smoking habits and dietary factors.

• Mediastinal Tumours: These are relatively uncommon but can affect people of all ages. In India, they are often found in young to middle-aged adults, and common types include lymphomas and thymomas.