There are trillions of cells in the body. These cells have a tightly regulated cell cycle that controls their growth, maturity, division and death. During childhood normal cells divide faster to allow the person to grow. Once adulthood is reached the cells divide to replace worn-out cells and to repair injuries. This cell division and growth is controlled by the cellular blue print or DNA and genes that lie within the cell’s nucleus.
Cancer begins when cells in a part of the body start to grow out of control. All types of cancer, irrespective of their origin, occur due to this disturbed growth of cells that leads to formation of tumours and lesions. In addition, the cancer cells possess some rogue like properties:
- They have longer life spans and instead of dying continue to grow and form new, abnormal cells
- Cancer cells can also invade other tissues. This is something that normal cells cannot do. This property is called metastasis.
- Cancer cells grow into tumors that are supplied by a new network of blood vessels. This is called angiogenesis and is unique in maintaining the blood supply and supply of nutrients to the cancer cells.
What makes a normal cell turn cancerous?
A normal cell can become a cancer cell if it undergoes damage to the DNA. Since it is the DNA that regulates the cells’ cycle of growth and death and any changes or damage to DNA affects the cell.
For most cells if the DNA is damaged the cell either repairs the damage or the cell dies. In cancer cells, the damaged DNA is not repaired and the damage is propagated to newer abnormal cells that are born of the defective cell.
Damaged DNA by mutation can also be inherited from parents or relatives. DNA damage can also occur due to exposure to toxins like cigarette smoking, alcohol etc.
Breast Cancer Pathophysiology
Breast cancer is a malignant tumor that starts in the cells of the breast. Like other cancers, there are several factors that can raise the risk of getting breast cancer. Damage to the DNA and genetic mutations can lead to breast cancer have been experimentally linked to estrogen exposure. Some individuals inherit defects in the DNA and genes like the BRCA1, BRCA2 and P53 among others. Those with a family history of ovarian or breast cancer thus are at an increased risk of breast cancer.
The immune system normally seeks out cancer cells and cells with damaged DNA and destroys them. Breast cancer may be a result of failure of such an effective immune defence and surveillance.
These are several signalling systems of growth factors and other mediators that interact between stromal cells and epithelial cells. Disrupting these may lead to breast cancer as well.