What is Cancer?
It is an abnormal growth of cells. We all have abnormal cells in our body. Our cells get hurt all the time from particles in our environment or by the items we ingest into our bodies. Our body tries to find those abnormal cells and repair them and if it can’t repair the cell, it sends it to apoptosis or cell death.
The lower portion of this slide represents a mass of cells that can grow when this abnormal cell is not identified. This replication of cells can become a mass of cells called a tumor. The tumor can be either benign or malignant. A benign tumor becomes noticeable as it replicates and stays at the original site, getting bigger and finally pushing on other body parts.
A malignant tumor's cells have the ability to shed from its original site and travel to other parts of your body as it grows and replicates. These cells can travel through the bloodstream or through the lymph fluid. The cells then stop and begin replicating wherever they land. This mass of cells (tumor) interrupts the normal function of that body part. The ability of the cells to move, replicate and interrupt normal cell function is what makes them malignant.
Importance of Type & Extent of Cancer
When tumors are found, a biopsy is done and the type of cancer is diagnosed. As the above slide shows, there are carcinomas, leukemia, lymphomas and sarcomas. The left side represents carcinomas. Carcinomas affect the lining of our organs. The lining can be of the lung, breast, colon, etc. Skin is also a lining and has basal, squamous and melanin cells. The type of treatment implemented is based on the cell type because the drug that works for basal cell doesn’t necessarily work for squamous and will not work for a melanin cell.
It is important to find out which cell lining the cancer arose from. For example, two people are diagnosed with lung cancer, if one has squamous cells cancer and the other has adenocarcinoma they will receive different chemotherapy agents.
This slide also shows leukemia, which starts within the blood producing cells; lymphoma, which starts within the lymph system; and sarcomas that start within fat, bone or muscle. If the cancerous tumor started in the colon and spread to the lymph nodes, it doesn't mean lymph cancer is present. It means colon cancer is in the lymph system and treatment is for colon cancer. Colon and lymph cancers require totally different drugs.
Knowing this information about the cancer and if it is local (still at the site of origin) or has spread (moved to other body parts) helps in the treatment decision and determines the length of treatment. In the past, we only had surgery, a limited number of drugs to use, and radiation. Now we know so much more about the tumors we can determine the best course of treatment. Should surgery come or can we shrink the tumor to decrease the extent of surgery required. There are so many variables with each client that extensive testing is now done to determine the specific drugs to use for your tumor type.
Why are there side effects to Chemotherapy?
Now we know the treatment regimen, which drugs will be used, in what order to perform chemo and surgery, and if radiation is necessary. Once the drugs have been chosen it is important to understand how chemotherapy works and what it is doing within the cell so you can better understand the possible side effects.
Chemotherapy works on the life cycle of the cell. Every cell in our body goes through this life cycle.
G0 – is a resting phase.
G1 – the body needs the cell to replicate; the cell moves from G0 to G1 but it needs nutrients to start the replication process and then it moves to the S phase.
S – is a very active phase of cell development where all of the DNA replicate and all of the chromosomes have been doubled.
G2 – is a phase where the spindle starts forming.
M – is mitosis or cell division. The chromosomes have doubled and need to separate; they polarize from each other; the spindle between them breaks and they become two separate cells.
Chemotherapy works by interrupting the cell development somewhere along that process. Chemists have created drugs that look like nutrients the body needs, but they left something out and when the cell pulls it in and tries to use the nutrient it can’t and the cells die.
Another drug can crystallize the spindle between the cells, they cannot divide and the cells die. We now know more about each tumor type and we have more options specific to that individual treatment course. We know how to use these drugs with other chemotherapy agents, shorten the timeframe between doses and add chemotherapy during the radiation treatment course to enhance the effect of radiation.
The diagnosis, cell type and extent of disease is known and the treatment course has been decided.
Now it is time to discuss the side effects of chemotherapy. Chemotherapy works by affecting rapidly reproducing cells. Cells that are going through the life cycle quickly tend to be:
- Cancer cells – tend to not have an effective stop mechanism, they just keep on replicating.
- Some good cells also reproduce rapidly (hair, mouth, throat, stomach, bowel lining and bone marrow) and will absorb chemotherapy drugs thinking they are necessary, but ultimately the drugs damage the good cells.
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