CAUSES OF CANCER THAT CAN BE PREVENTED

Introduction

Just to take you through a crush course of biology, human body is a complex structure with small functional units called cells that are specialized to carry out different functions. Cells which are similar structurally and in function are grouped together to form tissues and tissues form organs. Organs further group together to form systems.

By the process of mitosis, body cells replicate to form identical daughter cells. This process is called cell replication and is controlled by proto-oncogenes. Proto-oncogenes are genes found in a cell that enables normal cell growth and division.

The body has Tumor Suppressor Genes which helps to moderate the rate of cell division. They also function to get rid of old and defective cells in the body by causing programmed cell death (cell apoptosis). All this is a natural process which should occur undisturbed in order to produce a healthy and well functional body. 

On the other hand, proto-oncogenes can be activated to oncogenes which causes abnormal cell growth and division. This occur as a result of mutation in genetic make-up of the cell.

Similarly, tumor suppressor genes can also undergo mutation resulting into chaotic uncontrolled cell growth and division and the process of programmed cell death is also interrupted. When the cell apoptosis and defective cell repair is not achieved, more defective cells are produced at an alarmingly higher uncontrolled rate. This forms the basis for etiology of cancer.

CANCER RISK FACTORS

GENETIC PREDISPOSITION.

There has been a rampant concern in respect to hitherto rising cases of cancer. Basically, cancerous cells are abnormal in their genetic structure resulting into uncontrolled cell growth and division.

Inherited mutated genes accounts for early onset of various cancers in life. During fertilization, the ovum fuses with a spermatozoa to form a zygote which divides and grows to form an embryo. Embryo further divides and grows to form a fetus then child. If the initial ovum or sperm or both had mutated, each cell which forms from these parent cells has the mutated gene in it and may require only few mutations to form cancerous cell. This is the reason as to why genetically predisposed cancers tend to occur early in life. Adopting a healthy lifestyle has a diminutive effect on early onset of cancer cases in subjects who are genetically predisposed.

CIGARETTE SMOKING

According to American Cancer Society, "tobacco smoke is a mixture of gases and particles. It contains more than 7,000 chemical compounds. More than 250 of these chemicals are known to be harmful, and at least 69 are known to cause cancer." 

Mainstream smoke (exhaled by smoker) is less harmful than side stream (from lit cigarette) smoke. This translates to higher health risks to non-smokers who are closer to smokers but at the same time it doesn't exonerate the smoker from the said risks.

 

Smoking and exposure of non-smokers to cigarette smoke increases the risk of cancers of lungs, stomach, reproductive system and leukemia.

RADIATIONS

Both high frequency and low frequency magnetic radiations have been linked with increased risk to cancer. High frequency magnetic radiations are like X-rays, gamma rays, UV rays. They are also called ionizing radiations with ability to cause cell mutation at genetic level. This can lead to formation of cancer cells. 

Cell phones, computers, microwaves, radio and TV transmissions are low-frequency transmissions, non-ionizing and will not cause damage to the genetic material of the cell though this claim has not been fully substantiated.

The WHO's International Agency for Research on Cancer in their press release raised concern that, some form of non-ionizing radiation like these may have some form of biological effects that may result in cancerous cell transformation. 

ALCOHOL AND ALCOHOL ABUSE 

Ethanol (an active component of alcohol) and acetaldehyde (ethanol by-product) are both toxic to the body and carcinogenic.  

According to National Cancer Institute, the more alcohol an individual consumes, the more the risk of developing alcohol-associated cancer like cancer of the mouth, esophagus, head, liver (common), colorectal and breast. 

Alcohol also increases the level of endogenous estrogen in the body which has been implicated with cancer of the breast, uterus and ovary. 

ONCOGENIC VIRUSES AND BACTERIA

These oncogenic biological agents have a propensity to initiate the process of cancerous cell formation. They enter the human cell and cause changes in the structure of the DNA leading to mutation. A repeated damage to the cellular DNA structure may lead to cancerous cell transformation with time.
E.g

• Stomach cancer- associated with infection with Helicobacter pylori which is also the major risk factor to development of stomach and duodenal ulcers. People with stomach and/or duodenal ulcer should also be tested for H.pylori infection in order to take a prompt action by initiating treatment.
• Hepatocellular (liver) cancer- is linked with hepatitis B and C infection. 
• Cancer of the cervix- infection with Human papilloma virus (HPV) increases it risk. HPV infection increases the risk of genital warts, anal cancer. 
• Urinary bladder cancer- linked with Schistosoma hematobium infestation.

OBESITY

According to National Cancer Institute, obesity is associated with increased risks of certain cancers to include cancer of "esophagus, pancreas, colon and rectum, breast (after menopause), endometrium (lining of uterus), kidney, thyroid, gall bladder." 

Obese people have high amount of fat under the skin which has been implicated to produce excess estrogen in the body. High amounts of estrogen in the body increases the risk of estrogen responsive cancers of the breast and endometrium common post-menopausal women. 

With aid of research, there is also a substantial body of evidence that obesity increases the risk of developing of certain tumors in the body. Obese people have a higher metabolic rate with insulin levels higher than that of non-obese individual. They also have insulin like growth factor and all this compounds to increase the risk of certain tumors in the body.

OTHER CANCER RISK FACTORS:- 

• Lack of physical activity
• Chemical inhalations e.g in rubber industry. 
• Vehicle exhaust especially Diesel engines
• Asbestos, arsenic, formaldehyde.

REFERENCES
The chemistry of life- Ross and Wilson textbook of Anatomy and Physiology in health and illness. 10th Edition, 2006 by Ann Waugh, Allison Grant.

Press release: International Agency for Research on Cancer declares second-hand smoke carcinogenic to humans. May 2004- World Health Organization. Viewed on Jan 2015.

Secondhand smoke -American Cancer Society, Revised Nov 2014.

A review of human carcinogens-part D: radiations- The Lancet Oncology.

Alcohol and cancer risk-National Cancer Institute. Viewed on Jan 2015.

A review of human carcinogens- part B: biological agents-The Lancet Oncology.

Obesity and Cancer risks-National Cancer Institute At the National Institute of Health. Viewed in Jan 2015.