The human body is made up of billions of tiny cells, collectively forming tissues and organs which are necessary for maintaining an optimum functional capacity. Interestingly, we all start life as a single cell; this cell rapidly divides and ultimately result in a complex structure full of complicated metabolic activities, taking place in every millisecond.
The 4 major types of genes responsible for cell division include oncogenes which instruct cells when to divide, tumor suppressor genes which instruct cells when not to divide, Suicide genes which control apoptosis or natural cell death which tells cells to kill itself if something goes wrong and DNA-repair genes which instruct cells to repair damaged DNA.
Having said that, this article describes,
1. What is a Cancer?
– About Cancer
– Benignant vs Malignant Tumors
2. How Do Cancer Cells Develop?
– Malignant Transformation
– Initiation and Causatives
– Promotion and Causatives
– Blood Supply – Natural Enhancer
3. How Do Cancer Cells Spread?
What is a Cancer
Cancer is the term given to a class of diseases characterized by an abnormal division of faulty cells manipulated by DNA mutations (some sort of a disturbance in one or more of the above-mentioned gene types), in an overrated manner which eventually invade the surrounding tissues and disrupt their normal functional capabilities.
Being one of the leading causes of increased mortality and morbidity worldwide, there are more than 100 different types of cancers that have been identified so far and they are named according to the first most cell type, affected.
E.g. Breast cancer, Lung cancer, Colon cancer, Prostate cancer, etc.
When altered cells divide in an uncontrollable manner, they will eventually give rise to lumps and masses of tissue known as tumors, except in Leukemia, where the invasion occur in the blood stream. These tumors will grow rapidly and disrupt various systems in the body, including digestive, nervous, respiratory and circulatory systems. They are also capable of releasing several hormones which can drastically alter the functions in the body.
Benign vs Malignant Tumors
Tumors which stick to one site and demonstrate only a limited growth are referred to as Benign, whereas ones that can spread all over the body by invading every nook and corner, are referred to as malignant.
Benign tumors can be treated effectively with chemotherapy and other cancer treatments whereas malignant ones are highly fatal, and respond poorly to medication or surgery with a poor prognosis. These have a higher chance of invading blood and lymphatic system since there is a special process called Angiogenesis through which they develop their own blood vessels for the purpose of getting nourished. This special process by which primary malignant cells move to distant sites, lodge there and disrupt the structure of organs is known as Metastasis.
However, all factors are based on the type of cancer, site, severity and overall fitness of the affected individual.
How Do Cancer Cells Develop
Malignant transformation is a complicated process by which healthy cells gradually convert into cancerous cells in the body.
Initiation and Causatives
This is the first step in cancer cell formation, where the changes seen in individual cells, related to genetic material, molds the primary cell to become cancerous. This can either occur spontaneously or by various substances known as Carcinogens.
Commonest Carcinogens which are known to be responsible for the development of cancer include tobacco, alcohol, fast food, carbonated drinks, exposure to UV rays from the sun, viruses such as Hepatitis B and C, human papilloma virus, genetic causative agents and positive family history.
When our bodies get exposed to these factors, chemicals called free radicals are formed, and they try to steal electrons from other healthy molecules in the body. In fact, these free radicals damage healthy cells in the body in order to fill their deficit and function well.
There is also a significant effect of gender on causing certain carcinomas as follows.
- Commonest cancer among men- lung cancer, prostate cancer, colon cancer, rectum, stomach, and liver cancer.
- Commonest cancer among women – breast cancer, colon cancer, rectum, lung, cervix, and stomach cancer.
However, Carcinogens do not have the ability to affect cells in an equal manner. In fact, some cells which already own some sort of a genetic susceptibility may be affected in a higher incidence than rest of the cells.
Cancer cells which are present in a certain body tissue from what they develop originally are known as Carcinoma-in-situ which is characterized by a superficial cell growth.
E.g. Epithelial lining of bladder or ducts in the breast.
However, rapid replication or division of these first most cancer cells will ultimately end up invading the basement membrane which helped to keep them localized to a site and then it will be known as invasive cancer.
Promotion and Causatives
This is the second type of precipitation which leads to the development of cancer cells. The substances responsible are called Promoters; they are sometimes present in the environment, naturally or in the form of drugs like man-made sex hormones. In contrast to carcinogens, promoters cannot create cancer by themselves. Instead, they let a cell that has already undergone the first most step-initiation to become cancerous.
Furthermore, there are some carcinogens which are powerful enough to cause cancer without the need for any promotion.
E.g. Ionizing radiation (nuclear weapons, X-rays) can result in various cancer types such as sarcomas, leukemia, thyroid cancer and breast cancer without any promotional factors.
Blood Supply – A Natural Enhancer
At one point, these rapidly dividing cells will run out of nutrition and oxygen provided by the normal blood vessels; they will send a signal to certain hormones inside the body which will induce, producing new blood vessels by a process known an Angiogenesis.
This is the turning point of growth in malignancy. Angiogenesis occurring effectively this way will be an enhancer for cancer cells to divide in a more frequent manner, ultimately resulting in a bigger tumor.
Read: How Do Cancer Cells Spread
“Diagram showing how cancer cells keep on reproducing to form a tumor CRUK 127” By Cancer Research UK – Original email from CRUK (CC BY-SA 4.0) via Commons Wikimedia
“Cáncer1EN” By Jeanne Kelly of Aaardvark Inc. – From the National Cancer Institute. This file was derived from Normal cancer cell division from NIH-2.svg (Public Domain) via Commons Wikimedia