In the recent years, there has been an increase in the number of people who are diagnosed with cancer. The reason for this increase is not clear. There are many factors that contribute to the rise of cancer cases. One of them is lifestyle. In fact, the changes in lifestyle have increased the risk of developing cancer. Some of these changes include:
• Smoking
• Obesity
• Lack of exercise
• Eating habits
• Lack of sleep
• Stress
The above mentioned factors can cause cancer. But what causes cancer? The answer is still not known. However, it is believed that there are certain genes which predispose you to develop cancer. These genes are called “oncogenes”. Oncogenes are responsible for causing the growth of abnormal cells. This abnormal growth leads to cancer.
Oncogenes are present in all of us. They are present in our body cells as well as in our blood cells. These oncogenes are present in the form of DNA (deoxyribonucleic acid). DNA is a very important molecule in the body. It contains the genetic information of the cell. DNA consists of two strands. Each strand consists of four different bases: adenine, thymine, guanine and cytosine. The order of the bases in each strand determines the sequence of the gene. For example, if we consider the sequence AGGG, then we can see that the first base is A. The second base is G. The third base is G and the fourth base is G. This sequence repeats itself throughout the gene.
Each gene is made up of 3 or more such sequences. These sequences are called “exons”. These exons are separated by “introns”. Introns are non-coding regions of the gene. The exons code for proteins. Therefore, the intron regions do not code for any protein. The exons are transcribed into RNA (ribonucleic acid) molecules. The RNA molecules are then translated into proteins.
Some of the oncogenes are present only in some tissues. For example, one oncogene is present in the brain but not in the liver. The other oncogenes are present everywhere in the body. This is why they are also called “cancerous” genes.
A mutation in the oncogene may occur due to various reasons. For example, exposure to radiation, viruses, chemicals and toxins may cause a mutation. Also, some inherited diseases may cause mutations. Inherited diseases include:
- • Familial adenomatous polyposis
- • Lynch syndrome
- • Hereditary breast cancer
- • Hereditary colon cancer
- • Li-Fraumeni syndrome
- • Retinoblastoma
- • Cowden syndrome
- • Werner syndrome
These inherited diseases cause mutations in the oncogenes. The mutations lead to cancer.
Cancer develops when normal cells become abnormal. Normal cells are called “healthy cells”. Cancerous cells are abnormal cells. When a healthy cell becomes abnormal, it forms a tumor. Tumors are the visible signs of cancer. The tumors grow and spread to other parts of the body. This is how cancer develops.
