Cancer occurs when there are more abnormal cells than the immune system can handle. Instead of dying, the abnormal cells continue to grow and divide, accumulating as tumors. Eventually, this out-of-control growth causes the abnormal cells to invade surrounding tissues.
Our body is made up of trillions of cells. Normally, new cells replace old or damaged cells as they die. Sometimes a cell’s DNA becomes damaged. The immune system can generally control a small number of abnormal cells that prevent further damage to our body.
Read on to learn how cancer spreads, how it’s staged, and how different treatments work.
Why does cancer spread?
Cancer cells – PHOTO: Freepik@leonrahman22
Cancer cells don’t respond to the signals that tell them it’s time to die, so they continue to divide and multiply rapidly. And they are very good at hiding from the immune system.
When cancer cells are still contained within the tissue in which they developed, it is called carcinoma in situ (CIS). Once these cells grow outside the tissue membrane, it is called invasive cancer.
The spread of cancer from where it started to another place is called metastasis. Regardless of where it spreads elsewhere in the body, a cancer is still called the cancer from where it originated. For example, prostate cancer that has spread to the liver is still prostate cancer, not liver cancer, and treatment will reflect this.
While solid tumors are a feature of many cancers, this is not always the case. For example, leukemias are cancers of the blood that doctors refer to as “liquid tumors.”
Exactly where cancer cells will spread next depends on where they are in the body, but they are likely to spread nearby first. Cancer can spread through:
Woven. A growing tumor can push through surrounding tissues or into organs. Cancer cells from the primary tumor can break off and form new tumors nearby.
The lymphatic system. Cancer cells from the tumor can spread to nearby lymph nodes. From there, they can travel throughout the lymphatic system and initiate new tumors in other parts of the body.
Blood flow. Solid tumors need oxygen and other nutrients to grow. Through a process called angiogenesis, tumors can cause new blood vessels to form to ensure their survival. The cells can also enter the bloodstream and travel to distant sites, according to Healthline.
The fastest and slowest types of cancer
Cancer cells that have more genetic lesions (poorly differentiated) usually grow faster than cancer cells with fewer genetic lesions (well differentiated). Depending on how abnormal they appear under the microscope, tumors are classified into several types.
Some cancers that are generally slower growing are:
– breast cancers, such as estrogen receptor-positive (ER+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancers
– chronic lymphocytic leukemia (CLL)
– colon and rectal cancers
– most types of prostate cancer
Some cancers, such as prostate cancer, can grow so slowly that your doctor may recommend a “watchful waiting” approach rather than immediate treatment. Some may never require treatment.
Examples of fast-growing cancers include:
– acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).
– certain types of breast cancer, such as inflammatory breast cancer (IBC) and triple negative breast cancer (TNBC)
– large B-cell lymphoma
– lung cancer
– rare prostate cancers such as small cell carcinomas or lymphomas
Just because you have a fast-growing cancer doesn’t necessarily mean you have a poor prognosis. Many of these cancers can be treated effectively. And some cancers don’t necessarily grow faster, they’re less likely to be detected until they’ve metastasized.
What do stages have to do with the spread of cancer?
Cancers are staged based on the size of the tumor and how far it has spread at the time of diagnosis. The stages help doctors decide which treatments are most likely to work and provide an overview.
There are different types of staging systems, and some are specific to certain types of cancer. The following are the basic stages of cancer:
In situ. Precancerous cells were found, but they had not spread to the surrounding tissues.
Located. Cancer cells have not spread beyond where they started.
Regional. The cancer has spread to nearby lymph nodes, tissues, or organs.
Distant. The cancer has spread to distant organs or tissues.
Unknown. There is not enough information to determine the stage.
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