Cancer: Types, Causes and Symptoms

Cells are the basic structural and functional part of a living organism. During a normal cell cycle, cells divide into new cells and replace the old cells that die. But what if the mechanism that controls the cell division fails? What if the cells that works normally starts behaving abnormally and starts ignoring instructions and continues growing and dividing vigorously? The cells that  have abnormal growth are called cancerous cells. Cancer is a group of diseases that results due to abnormal growth of cells. It affects numerous vital organs of our body leading to death.

A normal cell grows and divides at a normal rate. But a cancer cell starts growing rapidly and divides vigorously.  This leads to loss of contact inhibition and anchorage dependence. In the case of cancer, the older cells are not replaced and they start forming a mass of cells, also known as tumor. The tumor formed serves no purpose in the body and takes disproportionate amount of nutrient.

 Types of Tumor

  • Malignant tumor
  • Benign tumor
  1. Malignant tumor: Malignant tumors are cancerous. In this type of tumor, cells grow faster over each other than the normal rate. The cancerous cells grows quickly, invades the nearby tissues and spread to different body parts. These cells are transferred from one body parts to the other body parts through blood stream. Sometimes these cancerous cells collect in different body part and form tumor. This is a multi-step process known as metastasis or secondary cancer.
  2. Benign tumor: Benign tumors are non-cancerous tumor. Cells grow slowly and do not spread to different body parts. It can be cured by meditation. Once cured it does not come back easily.

Causes of Cancer

Cancer is one of the most complex diseases with multiple causes. It basically results due to failure of cell cycle control. One of the known causes of cancer is genetic variations. Genetic variations can be of two types:

  1. Pre-disposed: Genetic variations that are already present from birth. Also called congenital variations. For example: Leukemia
  2. Acquired: The genetic variations acquired by habits and lifestyle modifications are called acquired genetic variation. For example, variation due to tobacco smoking and drinking.

These genetic variations  lead to  mutations in DNA. They result in breakdown of cell to cell communication and bypasses the checkpoints of cell cycle. Also apoptosis checkpoints and pathways become ineffective. This in turn results in growth of cancerous cells and spreads in the body. Sometimes it may lead to death.

To know more about cancer and its causes, watch the video.

Practise This Question

Viral genomes also contain some cancer causing genes. What are these genes called?