Cancer

 

Cancer affects our lives perhaps more than any other disease. 9.6% of Americans will be diagnosed with some form of cancer during their lifetimes. (CDC) But what is cancer? Cancer is the out of control reproduction of mutated cells. As cancer cells divide, they become more and more resistant to the regulating signals that control their growth and reproduction. They divide with increasing frequency, which eventually creates tumors that can impair bodily functions and eventually lead to death. (Scitable) About 605,000 Americans die from cancer each year. (CDC)

What causes Cancer? 

How do cells go out of control and become cancerous?  While not all of the details are known, we know that human DNA has genes called protooncogenes that help and control cell regulation. A mutation in one of these genes can cause them to become activated, turning them into oncogenes, which divide continuously. This can be caused by a few different things. One possible cause is gene mutations, which can be either inherited from parents or caused by mistakes during mitosis. Another is gene duplications, where cells end up with extra copies of one or more genes. Oncogenes can also be activated by chromosome rearrangement, an error where the type and number of genes are correct, but they are arranged incorrectly during mitosis. (American Cancer Society, 7-8) Cancer can also spread to other parts of the body through a process called metastasis, in which cancer cells enter the bloodstream and are transported to a new location. (Scitable)

How does the body respond to cancer? 

 Firstly, it tries to prevent cancer from occurring in the first place with checkpoints during mitosis that terminate cell division and kill the cell if an error is detected. Failing this, the body has two types of genes that are mechanisms for fighting against cancer. The first is tumor suppressor genes. These genes make sure that cells die at the right time, causing apoptosis, or programmed cell death. This prevents cell division from snowballing and developing tumors.  The second is DNA repair genes, which detect mistakes in DNA replication. When a mutation is detected, DNA repair genes attempt to rectify the mistake to prevent it from being passed on to the cell’s daughter cells. If it can’t fix the mutation, they will cause the cell to die. (American Cancer Society, 8-9)

How is cancer treated? 

Doctors have several methods for treating cancer. The most common three are surgery, chemotherapy, and radiotherapy. Surgery is an important cancer treatment. Surgeries can be exploratory, intended to find and diagnose cancer, or they can be used to treat or remove cancer directly. Surgery can cure several types of cancer, but curing cancer is often not so simple. Another type of treatment is chemotherapy. Chemotherapy uses cytotoxic, or anti-cancer, drugs to attack cancer cells directly. Unfortunately, chemotherapy also affects healthy cells and can have a number of side effects. Radiotherapy, on the other hand, is targeted at the affected area. There are two types of radiotherapy. Curative radiotherapy uses x-ray radiation to kill cancer cells and remove tumors, curing the cancer. If the cancer cannot be cured, palliative radiotherapy is used. This treatment uses x-ray radiation to treat the cancer's symptoms. (NHS Inform)

References

• Centers for Disease Control and Prevention. (2022). FastStats - Cancer. Centers for Disease Control and Prevention. https://www.cdc.gov/nchs/fastats/cancer.htm
• Scitable. (2014) Cell Division and Cancer. Scitable by Nature Education. https://www.nature.com/scitable/topicpage/cell-division-and-cancer-14046590/
• American Cancer Society. (2022). Oncogenes, Tumor Suppressor Genes, and DNA Repair Genes. American Cancer Society. https://www.cancer.org/cancer/understanding-cancer/genes-and-cancer/oncogenes-tumor-suppressor-genes.html
•   National Health Service. (2022). How is cancer treated? NHS inform. https://www.nhsinform.scot/illnesses-and-conditions/cancer/how-is-cancer-treated