Cancer in general

 CANCER:

Definition- uncontrolled division or growth of cells in the body, results in cancer.

Why cells divide?

As cells grow they become old and die, new cells replace them. Cells divide to make tissues, which play a major role in building our body system.

How cancer develops?

During cell division cells adapt to a series of events, and these events define a cell cycle. There is a chance that during Cell division, cell cycle can tend to make mistakes or regulate the cells to divide uncontrollably, which results in cancer growth. Normal cells divide infinitely and gives raise to cancer cells.

Mutation within the genes makes cells imbalance and this is also one of the reasons for origin of cancer. DNA damage leads to mutation in the genes, and this damage of DNA is due to the harmful environmental factors and lifestyle. Ultraviolent rays coming from sun also damage DNA creating thymine dimers and alkylated bases.

How cancer cells differ from normal cells?

Division of Normal cells is controllable and they respond to signals given by body to stop cell division. They work in coordination with the body system. But the scenario is different in cancer cells, they no longer respond to signals that control cell division and death. They overcome apoptosis or programmed cell death (APC).

Special thing about cancer cells is that they spread to other parts of the body (Metastasis). Normal cells won’t move when they come in contact with other cells.

They trigger even immune system to work for them and protect them instead attacking.

Stimulate blood vessel to grow towards tumors, thus tumors receive oxygen for survival. 

Modify their chromosomes, like duplication, deletion, insertion of chromosomal parts. Likewise they differ in their chromosomal number.

Tumors depend on normal cells for nutrients.

They also increase the half-life of enzyme telomerase for the production of telomeres which protect the DNA ends.

Metastatic tumor: Tumor which spreads to others parts of the body from the origin (primary cancer) through breaking the walls of the cell. Even though they spread to the other parts they remain as metastatic tumor only. For example, if the tumor spreads from lungs to liver, it is not called liver metastatic tumor it remains as lung tumor only.

Metastatic tumors are morphologically similar to the original cancer cells.

Metastatic cancer causes a severe damage to the body and leads to death.

Reference: PubMed, NCBI.