User:Kelsie.Kienapple/Cancer cell

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Cancer Cells are specialized cells that evade the body's immune system. They are able to stop the mechanism of programmed cell death, know as apoptosis and continue to divide, duplicating rapidly to form a tumor. In many countries, cancer is a leading cause of death for example, two in five Canadians will be diagnosed with cancer in their lifetime. Statistically speaking, survival rates are dependant on the location and type of cancer however, roughly 63.62% of individuals diagnosed with cancer will survive. This is not to say that they can never have cancer again as some will have reoccurring cancer diagnosis during the remission stage.

Classification[edit]

There are different categories of cancer cell, defined according to the cell type from which they originate.

• Carcinoma, the majority of cancer cells are epithelial in origin, beginning in a tissue that lines the inner or outer surfaces of the body.
• Leukaemia, originate in the tissues responsible for producing new blood cells, most commonly in the bone marrow.
• Lymphoma and myeloma, derived from cells of the immune system.
• Sarcoma, originating in connective tissue, including fat, muscle and bone.
• Central nervous system, derived from cells of the brain and spinal cord.
• Mesothelioma, originating in the mesothelium; the lining of body cavities.

Kienapple/Cancer cell

Cancer cells are cells that divide continually, forming solid tumors or flooding the blood or lymph with abnormal cells. Cell division is a normal process used by the body for growth and repair. A parent cell divides to form two daughter cells, and these daughter cells are used to build new tissue or to replace cells that have died because of aging or damage. Healthy cells stop dividing when there is no longer a need for more daughter cells, but cancer cells continue to produce copies. They are also able to spread from one part of the body to another in a process known as metastasis.

Typically, when a cell is not functioning optimally, the body orders it to be killed via the process of apoptosis, otherwise known as programmed cell death. Apoptosis begins with one of two pathways: the Intrinsic pathway or the Extrinsic pathway (Sharma et al. 2019). In either case, pro-apoptotic proteins are the key mechanism that induces apoptosis. These are more commonly referred to as the BCL-2 family, a group of vital signaling proteins that is responsible for the regulation of apoptosis (Sharma et al. 2019). This includes important proteins BAC and BAX (Sharma et al. 2019). When these cells interact with the mitochondrial membrane and the protein BH3-only proteins, it allows for the release of cytochrome-C which leads to the formation of an apoptosome, a platform that activates the caspase cascade and the final steps of apoptosis .

Cancer cells are able to up-regulate the pro-apoptotic proteins BAK and BAX, however, their activator BH3 is down-regulated, meaning that the cell can evade initiation of apoptosis and continue to replicate via mitosis. The difference between the regular apoptotic process can be seen in comparison to the evasion of apoptosis in cancer cells can be seen in the following image.

Symptoms

The symptoms associated with cancer can vary drastically based on the initial tumor location. Nonetheless, the general symptoms experienced are:

• Chronic fatigue
• Persistent cough
• Irregular bowel and bladder movements that are coupled with a lack of control
• Bleeding or bruising without trauma
• Gastrointestinal pain
• Inability to heal
• Jaundice
• Drastic weight changes

In addition to all of these common symptoms, the individual will experience tenderness and pain in the area where the tumor resides.

Staging

There are four different types of staging that are used to determine the diagnosis of the individual. First, the physician will always start with clinical staging, where a physical examination occurs externally, through medical imaging and a biopsy.

After this occurs, the physician may decide to move forward with pathologic staging, by which a surgeon will explore the entirety of the tumor to get a good idea of its location, size, density etc. and in some cases, the surgeon will also remove the tumor in the same operation to minimize incisions and infection from operating twice . This will only occur after external treatments are done such as radiation or chemotherapy. There may be some physicians that would like to be cautious and take a second look before they move to surgical staging. This is where Post Neoadjuvant Therapy Staging will be used to observe the effectiveness of the chemotherapy and/ or radiation . In some cases, the tumor is not fully removed and the surgeon did not get clear margins. This requires restaging, to reevaluate the presence of the tumor and determine further treatment.

There are two other types of staging techniques used to determine the severity of cancer.

The four distinct stages of Cancer progression.

The number system ranks the cancer progression on a scale from 0-4 with zero being the minimal and 4 being the worst-case scenario. Stage 0 is known as In Situ, where cancer has not grown or spread to other regions of the body . Stage 1 is the localized stage, where the cancer is small but is not spreading to other regions. Size is observed in stage 2 when the cancer is actively growing but has not spread. Stage 3 is the regional stage by which the cancer is large and has begun to spread to surrounding tissues and lymph nodes. Finally, stage 4 is the distant stage where the cancer is large and has spread to other areas of the body that are not located directly beside the primary tumor. This is typically declared terminal and is not curable.

The other staging system used is TNM, where the tumor progression, presence in the lymph nodes and its metastasis amount are measured. When staging the tumor, the physician will evaluate the levels of tissue that tumor has invaded. The deeper the tissue, the higher the T number. When observing the lymph nodes, the presence of the tumor and cancer cells is ranked, again with the higher number being more severe . Finally, the metastasis is measured based on the tumor's relocation to other areas within the body, independent from the primary tumor location. If metastasis has occurred, then the patient will be in stage 3 or 4. Physicians will use a combination of the number system and the TNM system to stage and diagnose patients.