About Cancer


How does cancer spread?
Cancer spreads when cells from a primary tumour dissociate and enter the bloodstream or lymph system, in what is known as intravasation. Then cells move through the system they have entered in a stage known as circulation. Eventually the cancerous cells will leave the transport system in extravasation, before colonising a secondary site.

Notably, researchers have recently discovered a network of fluid filled tubes that account for about 20% of our fluid volume, and likely act as shock absorbers. They surround every tissue in the body and cancer cells that enter these channels have a direct passage into the lymphatic system, which leads to faster spread, but this revelation may help us tackle the task of slowing the metastasis (movement) of cancer.

To where do cancers most often spread?
Cancers often spread to the lungs, liver or lymph nodes first:

·        Blood is pumped to the lungs, and any cancer in the blood can become trapped in the capillaries, slowing them so that they can move into the lungs through the single layer of thin squamous epithelial cells.

·        Blood from the digestive system is first pumped to the liver before returning to the heart and lungs. Again, cancers can become lodged in capillaries, where they grow into secondary tumours.

·      Cancer cells are very likely to travel from where they originated to nearby lymph nodes, because there is a natural circulation of tissue fluid from organs to the lymphatic system.

What is the most common type of cancer?
Skin cancer is the most common, due to the skin’s exposure to UV light (which is a strong mutagen) from the sun. UV is absorbed by DNA and has been proven to have a strong correlation with certain cancers.

The next most common type of cancer is lung cancer which is also the most common cause of death by cancer. It is most often caused by smoking tobacco.

How does cancer transition from stage 0 through to stage 4?

Stage 0: Essentially, a completely curable localised tumour that has not grown into the surrounding tissues. These are known as benign tumours.

Stage 1: A small but malignant growth, with the ability to spread but not having done so yet.

Stage 2: A larger primary tumour confines to on organ but having spread to surrounding lymph nodes.

Stage 3: Known as locally advanced, these tumours have often spread to major blood vessels and lymph nodes but have not yet spread to other organs.

Stage 4: Fully metastasised cancer that has spread to other organs. Usually treated with experimental therapies, and known as advanced. Palliative care is sometimes the only option if the cancer was identified too late.

Thank you for reading this article, I hope you found it informative.

Louis Lane.

Sources:
http://www.who.int/news-room/fact-sheets/detail/cancer
https://www.newscientist.com/article/2164903-newly-discovered-human-organ-may-help-explain-how-cancer-spreads/
http://www.cancerresearchuk.org/what-is-cancer/how-cancer-can-spread/where-cancer-can-spread
https://www.cancer.org/treatment/understanding-your-diagnosis/advanced-cancer/what-is.html


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