4 min|Dr. Alex Chan
Cancer: When Good Cells Go BadHealth
Today, Dr. Alex Chan contributes to our blog with a post about the pathogenesis of cancer. Dr. Alex Chan completed a two-year residency at Integrative before joining the clinic in full time private practice and as the Residency Program Coordinator. Dr. Alex Chan has a special interest in integrative cancer care and has devoted herself to additional training in the field of oncology. She applies this extensive knowledge to treating patients within our Cancer Program.
Cancer continues to be an epidemic across age, gender and the world.
However, did you know that cancerous cells are found in healthy people at all times? What separates cancer as a disease process rather than a normal occurrence is the manner in which our cells divide, spread and behave. Normal cells transition through a cycle of cell division that is controlled by regulatory and growth factor genes. During this process our cells sometimes create errors in their replication of DNA and other mutations.
To prevent these mutations from being harmful we have genes that mediate DNA repair and some that signal cell death if necessary. The difference with cancer is that these cells manage to avoid each of these protective steps and multiple mutations in each class of control genes allows for a malignant expression.
An increasing number of dysfunctional cells sets the stage for growing cancer cells.
It’s important to remember that the cancer process is an extreme version of normal malfunction. Good cells go bad and become dangerous more quickly depending on the following physiological cell processes: differentiation, growth, angiogenesis, local invasion, metastasis. Differentiation is how cells grow, look and react to their environment. Cancerous cells display anaplasia which is abnormal cell growth, with abnormal tissue structure that is invasive and not reversible.
In terms of malignant transformation, this is the worst-case scenario compared to hyperplasia, the reversible increase in normal cells. Anaplastic cells grow strangely, look funny, take over the region of the body they are growing in, and do not regress.The growth patterns of cancer cells are also unique. Healthy cells have set growth rates and fail safes to prevent over growth. Cancer cells lose the sense of 'contact inhibition' - when the same types of cell grow to a point where they touch each other their growth subsides so that only an appropriate number of cells are formed.
Losing contact inhibition causes excessive clumps of cells to form as is seen in tumors. The speed at which these cells grow is often related to how well differentiated the cells are with more malignant, poorly differentiated cells growing faster and benign hyperplastic cells growing slower.The ability of a tumor to form and recruit its own blood supply is called angiogenesis and is critical to its ability to grow and adapt to its environment.
Cancerous tissue has mutations that allow for uncontrolled growth and promotes angiogenesis of vasculature that is chaotic and irregular. Differences in these vessels mean that the tumor tissue does not receive blood in the same way as normal tissue and this can limit the penetration and effectiveness of chemotherapy. Cancer cells have the ability to spread both locally by directly invading the surrounding tissue and systemically through blood and lymphatic vessels and implantation. Cancer cells become more dangerous as they spread as this metastasis decreases the efficacy of local treatments like surgery and radiation and means the cancer process is more advanced.
Understanding the biology of cancer allows us to target particular stages of the disease. Recognizing the ways in which cancer evades our normal protective mechanisms empowers us to focus on reigniting those safe guards.
The key to treating cancer is held within each of our cells - we just need to help them remember how to protect themselves.