Pathophysiology of Cancer
Cancer is disease of regulation of tissue growth. In this disease, the cells of the body display uncontrolled growth, invasion that intrudes and destroys adjacent tissues and spreads to other body locations. In order for a normal cell to transform into a cancer cell, genes which regulate cell growth and differentiation must be altered.
Theories about Cancer
- Cellular transformation and Derangement theory. In this theory, exposure of normal cells to some etiologic agent may transform normal cells into cancer cells.
- Failure of the Immune Response Theory. This theory conceptualizes that all individuals possess cancer cells but these cancer cells are NOT recognized by the immune system. Thus, cancer cells undergo destruction. Failure of the immune response system to kill or destroy the cancer cells leads to cancer.
Etiologic Factors or Carcinogens
- Viruses or Oncogenic Viruses. Prolonged and recurrent viral infections may lead to the breakdown of the immune system. The overwhelmed immune system may fail to destroy the cancer cells present in the body. The human papillomavirus (HPV) are particularly common cancer-causing virus which is well-known for causing genital warts and all cases of cervical cancer.
- Chemical carcinogens. These chemicals cause cell mutation or alter the cell enzymes and proteins.
- Vinyl chloride – plastic manufacture, asbestos factories, construction works
- Polycyclic aromatic hydrocarbons
- Weed killers
- Dyes – analine dyes (most commonly found in beauty shops and used at homes), hair bleach
- Drugs – cytotoxic drugs, tar nicotine in tobacco, alcohol
- Diethystilbesterol (DES)
- Nitrites in bacon or smoked meat
- Talc (polished rice, salami and chewing gum)
- Food sweeteners
- Nitrosomines (rubber baby nipples)
- Aflatoxins (mold in nuts, grains, milk, cheese and peanut butter)
- Polycyclic hydrocarbons
- Physical agents
- From x-rays or radioactive isotopes
- From sunlight or UV rays
Physical irritation or trauma
- Pipe smoking
- Multiple deliveries
- Older individuals
- Women are more prone to breast, uterine and cervical cancer
- Men are more prone prostate and lung cancer
- Urban dwellers
- Chemical factory workers
- Personnel of radiology department
- Family history
Pathophysiology of Cancer
A healthy cell becomes a cancer cell by undergoing the following processes:
- Proto-oncogenes are changed to oncogenes. Proto-oncogenes are genes that are coded to maintain normal cell growth. In cases of a developing cancer, oncogene takes its place. Oncogene is a gene that makes cells grow and divide rapidly.
- Cancer cell grows and divides rapidly.
- Alteration of the tumor suppression genes takes place.
- DNA repair genes are altered and turned off.
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