Cancer is a complex genetic disease that is caused by specific changes to genes. These changes in the normal cell can occur in one cell or group of cells and are the main reason for a normal cell to transform into a cancer cell.

The normal cells are the body’s basic building blocks and possess precise characteristics that enable them to maintain the proper functioning of tissues and organs in the body. Once transformed into a cancer cell, it attains absolutely different characteristics, which we have described here.

How do the normal cells become cancer cells?

The genetic changes alter the process of how the cell grows and divides and also its function. However, not all changes cause cancer.

The genetic changes that cause cancer mostly affect three specific types of genes: proto-oncogenes, tumor suppressor genes, and DNA repair genes. These changes are sometimes called “drivers” of cancer.

Proto-oncogenes and tumor suppressor genes are involved in normal cell growth and division. DNA repair genes are involved in repairing damaged DNA.

The normal cell’s gradual transition into a cancer cell occurs through a progression of alterations. These alterations are typically genetic in nature and can be triggered by a number of factors such as exposure to tobacco smoke, hormones, certain viruses as well as exposure to environmental hazards such as radiation and carcinogenic chemicals.

These factors cause cells to divide wildly and invade the neighboring tissues.

Normal cells and cancer cells differences

1. Growth

The growth of the normal cells is controlled by external signals, which allow them to grow and divide only when required. Normal cells start growing only when they receive such signals. They reproduce with exactly the same characteristics.

On the other hand, cancer cells don’t stop growing and keep on replicating. They grow in the absence of signals telling them to grow. This uncontrolled growth by the cancer cells leads to the formation of a tumor. They never stop reproducing.

2. Cell life cycle

Normal cells undergo programmed cell death (apoptosis) as part of their normal life cycle. This helps to maintain a healthy state of cellular proliferation and death and control of metabolic function.

Cancer cells grow at a rapid rate in the absence of signals telling them to grow. They ignore signals that normally tell cells to stop dividing or to die (a process known as programmed cell death or apoptosis). They repeat the life cycle continuously and do not undergo apoptosis.

3. Location

Normal cells remain in their intended location and ‘stick together’ by maintaining selective adhesions that they progressively adjust. They stop growing when they come in contact with other cells. Additionally, they do not move around the body.  They stay localized in exactly the same place.

Cancer cells do not stay localized in one place. They spread into neighboring tissues and travel to distant areas of the body. They make the blood vessels grow toward tumors so they are supplied with oxygen and nutrients and the waste products from tumors are removed.

4. Function

Normal cells transform into specialized cells and perform specific functions. They can acquire different physical characteristics despite having the same genome. They are function-oriented.

Cancer cells are rudimentary, that is, they do not perform any cell function except that of multiplying.

5. Immune system

The immune system attacks the normal cells if they are damaged or undergo variation and turn into abnormal cells.

Cancer cells are able to disable the immune response so that the immune system doesn’t attack them. They deceive the immune system and “hide” from it allowing the cancer cells to grow.

6. Nutrition

Normal cells derive nutrition through normal angiogenesis (through normal blood vasculature).

Cancer cells form their own blood vessels to feed the tumor and derive nutrition for their uncontrolled growth, depriving the body of proper nutrition. They induce nearby normal cells to develop blood vessels to supply the tumor with nutrition.

7. Differences under the microscope

Normal cell morphology

  • Cell shape: Uniform
  • The nucleus of the cell: Single, spheroid
  • Chromatin: Fine, even distribution
  • Nucleolus: Single
  • Cytoplasm: Large volume
  • Growth: Controlled
  • Maturation: Specialized cells
  • Blood supply: Normal angiogenesis
  • Location: Remain localized

Cancer cell morphology

  • Cell shape: Irregular
  • The nucleus of the cell: Multiple, irregular
  • Chromatin: Coarse,  uneven distribution
  • Nucleolus: Multiple
  • Cytoplasm: Small volume
  • Growth: Uncontrolled
  • Maturation: Remain immature
  • Blood supply: Tumor-induced angiogenesis
  • Location: Spread locally and to distant regions

8. DNA

Normal cells have normal DNA and a normal number of chromosomes with no abnormal changes.

Cancer cells often have an abnormal number of chromosomes. The DNA becomes increasingly abnormal with subsequent mutations.