Metastasis: How does Cancer Spread?

While people often talk about types of cancer as though they are all the same, it really couldn’t be further from the truth. Not only are different cancer types very diverse but also each individual type can have their own subtypes, along with different phases the cancer itself can be in. These phases are loosely based on how far the cancer has spread from the original site. The spread of cancer to other types of the body is known as metastasis.

When a cancer undergoes metastasis, it travels to other organs in the body. Some of the most common areas attacked during metastasis are the brain, lungs, liver and nearby bones. These traveling cells are the same genetic structure as those at the original site. This means that, while the cancer can travel to other organs like the brain, it is still considered to be part of the original cancer (i.e. lung cancer that spreads to the liver is still metastatic lung cancer). Metastasis is involved in the vast majority of cancer-related deaths.

In order to metastasize to a new site, a tumor requires a subset of conditions. Cancer cells must first break off from the primary tumor and pass through the area surrounding the lesion and into the blood vessel or lymphatic system. The cell must survive long enough to travel to a distant sight, work its way through the wall of the blood or lymph vessel and then settle and divide, before the immune system or treatment methods kill the cells. This video gives a good visual explanation as to how metastasis in cancer works to develop a tumor in another area of the body:



Due to the facts that many people are unsure of cancer symptoms, some cancers show little to no obvious symptoms and individuals may have an aversion to seeking medical attention, many patients have metastatic cancer already, by the time that they are diagnosed. Many cancer types – including the ones that may be socially viewed as being less dangerous – can metastasize to vital organs. This can include skin cancers. In fact, once melanoma has spread to distant organs (phase IV), the 5-year survival rate is only 15%-20%.

The simplest way to prevent metastasis is through routine screenings, exams, and self-checks (in the case of skin, breast and several other types that can be noticeable without a medical scan). Some cancer types may receive treatment specially designed to kill cells that may be in transit to other areas. At OncoSec, our ImmunoPulse technology currently undergoing clinical trials is specifically geared towards late-stage cancers including metastatic melanoma. With further data to be released surrounding our phase II trial for metastatic melanoma, please stay tune to our press release page.

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(Main image by deviantART user voxel123)