Life Sciences Glossary: Cancer, Major Types and Causes of Cancer

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Cancer

Cancer is a complex group of diseases that can affect many different body cells and tissues. All cancers are characterized by the uncontrolled growth and division of cells. Cancer leads to a mass of cells termed as neoplasm (Gr. For new formation) or tumor. Abnormal and persistent cells division localized in a particular region is called benign tumor. Benign tumor contains well- differentiated cells, not usually dangerous. Tumor cells may be carried by blood stream or lymph or penetrate directly to other parts of the body resulting in dangerous malignant tumors. The spread of cancerous cells to distant sites is termed metastasis.

Major Types

Pathologically cancers may be broadly classified into three major types:

  • Carcinomas are malignant growths of the epithelial tissue that cover or line body organs.
  • Sarcomas are malignant growths of the connective tissues that are derived from the primitive mesoderm.
  • Leukemia՚s result from unchecked proliferation of cell types present in blood and their precursors in the bone marrow.

Other terms associated with cancer are:

  • Melanoma: Cancer of pigment, cells of the skin.
  • Adenoma: Cancer of glands.
  • Moya: cancer of muscular tissue.
  • Lymphoma: Cancer of lymphatic tissue.
  • Glomma: Cancer of glial cells of CNS.

Causes of Cancer

Oncology is the study of cancer cells. All cells carry certain cancer producing oncogenes. Susceptibility to cancer depends upon familial factors, smoking, chemical and environmental factors, viral factor, alcohol and dietary factors, any agent that induces a cancer is carcinogenic or oncogenic agent. Exposure to ionizing radiations, such as X- rays, gamma rays, and non- ionizing UV- rays are said to induce cancer. Chemical substances that can cause mutation are called carcinogens. Physical irritants can also lead cancer, such as continued abrasion of the lining of the intestinal tract by some type of food. In many families, there is strong hereditary tendency to cancer. Viruses cause a number of specific cancers in animal. Tumor producing viruses are called oncoviruses. Lung cancer is by far the most common cancer in men, it is more than twice as common as skin cancer, the second most common type in men. In women, Brest cancer is the most common type, followed by the cancer of large intestine and rectum. Breast cancer is almost non- existent under the age of 25.

Diagnosis of Cancer

The diagnosis of cancer is usually done by:

  • Biopsy
  • X-ray and
  • Microscopic examination of body fluids including blood.

Treatment of Cancer

An early diagnosis of cancer is lifesaving, but if it is spread to various parts and organs, treatments become infective. Different treatments are prescribed for different cancers. Generally, a tumor is surgically removed wherever possible. Radiation is used to kill the cancer cells without harming the surrounding tissue. Sometimes drugs are used to fight cancer (chemotherapy) . These drugs either stop cancer cells from diving or are more toxic to cancer cells than to normal cells. A common weed Catharanthus roses is the source of two anti- cancer drugs, Vincristine and vinblastine, used in the treatment of leukemia.

Some Common Fungal Diseases

Some Common Fungal Diseases
DiseasePathogentransmission
Tiresias (Ringworm)Microspore Trichophyton EpidermalContact with hytonhyphal fragments
Cryptococcus՚sCryptococcus NeoformansAirborne cells
Candidiasis VaginitisCandidaAirborne Sexual
ThrushoynychiaalbinosContact Skin contact
HistoplasmosisHistoplasma CapsulateAirborne spores
Athlete՚s footTrichophytonAirborne Skin contact
Blast mycosisBalstomyces DermatitisAirborne spores
Aspergillosis OtomycosisAspergillums fumigatesAirborne spores

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