The biggest risk factor for developing lung cancer is smoking, I think we all know that. Unfortunately, over 10% of people who develop lung cancer have never smoked. 

Other lung exposure to nasty air of all varieties, or even second hand smoke from cigarettes, increases one's risk.

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Asbestos would spring to most people's minds, but interestingly it has a higher risk for cancer outside of the lung (mesothelioma) - in the spectrum of disease, not a good one to have. 

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The symptoms of a tumour in the lung include shortness of breath, dry cough, etc. However, some people won't get any of these symptoms depending on the location and size of the tumour. Some people's first symptom may be weight loss. It's a tricky one.

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A lot of lung masses are picked up incidentally. For instance, someone getting a chest x-ray for a chest infection may have a small lung shadow found opportunistically that warrants further imaging. 

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Lung cancers are described based on their subtype (cell appearance under a microscope) and location/spread. There are two main subtypes: small cell, and non-small cell. 

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Non-small cell lung cancers make up over 80% of tumours. They are further broken down into three: adenocarcinoma, squamous cell and large cell. 

It's a lot I know, but let's make it easier - where they like to live!

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Adenocarcinomas tend to hang out near the edges of the lung. 

Squamous cell carcinomas tend to hang out near the centre of the lung.

Large cell carcinomas aren't picky, they can be anywhere. 

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Small cell lung cancers (less than 20%) tend to grow and spread quite quickly. In fact, over two-thirds of people diagnosed with this form will present after it has already spread outside the lung. 

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Aside from primary lung tumours, the lungs are a hotspot for tumours born from the spread of other cancerous tumours.

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In terms of location, the right lung has three lobes (upper, middle and lower) and the left lung only has two (upper and lower) - to leave space for the heart. 

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If a tumour is in a single lobe, a lobectomy may be performed (removal of a lobe).

If the cancer has spread and tumours appear in multiple lobes on one side, a pneumonectomy may be performed (removal of a lung). 

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Lung cancers sometimes produce 'paraneoplastic syndromes'. Basically, the cancer cells pump out hormones that cause odd symptoms and disease. 

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Small cell carcinoma cells can produce excess ADH (Anti-diuretic hormone), leading to SIADH (Syndrome of Inappropriate secretion of ADH) - ugh, what a mouthful. 

It leads to your body inappropriately retaining too much fluid and your salt levels are diluted as a result ('Hyponatremia', for you nerds that care).

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Adenocarcinoma cells can produce too much ACTH (adrenocorticotropic hormone) which leads to an imbalance of your cortisol levels (cortisol is important for immune function, blood sugar and electrolyte regulation, bone and muscle health, blood pressure, etc.)...it does it all!

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Squamous carcinoma cells can produce too much PTH (parathyroid hormone) which is important in regulating your calcium and phosphate levels. Too much PTH can even lead to little holes in your bones!

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Like all cancers, lung cancers will be staged and treated accordingly - often with surgery and the adjuncts of chemo/radiotherapy.