10 Human Health and Diseases - part 07 - Cancer Cancer:

 

10 Human Health and Diseases - part 07 - Cancer

Cancer:

• Abnormal, uncontrolled and purposeless division of cells may lead to the formation/ development of mass of undifferentiated cell i.e. tumor. 
• When tumor is malignant, it is described as cancer and has ability to invade other tissues.
• Cancer harms the body when cancerous cells divide uncontrollably to form new lumps or masses of tissue called neoplasm (except in the case of leukemia). 
• Tumors can grow and interfere with the normal functioning of various organs. 
• They also release secretions which alter body function(s).
• It is one of the main killer diseases nowadays. 
• Physicians and researchers who specialize in the study, diagnosis, treatment and prevention of cancer are called oncologists.
• Tumors may develop anywhere in the body. 
• However, all tumors are not cancerous.
• There are two types of tumors: 

1. Benign or nonmalignant and 
2. Cancerous or malignant.

1. Benign or Nonmalignant Tumor :

• It grows slowly, may attain quite a large size, but it remains restricted to the site of its origin (localized) .
• Does not spread to other part of the body. 
• This does not necessarily mean that the benign tumors are not troublesome.
• Some benign tumors are harmful and fatal  
• e.g. brain tumor (A brain tumor may cause death because the brain is squeezed against the hard skull). 
• Moreover, the benign tumors may sometimes become malignant. 
• e.g. Adenoma and Fibroid.

2. Malignant tumor or cancer :

• The growth rate of this tumor is rapid and mortality rate is comparatively more than benign tumor. 
• Rapid growth of tumors causes overcrowding and disruption of normal cells.
• The cancerous cells compete with the normal.
• cells for nutrients and finally kill them.
• These cells are spread from one organ to other via blood or lymph and form new tumors called secondary tumors. 
• This migratory process is called metastasis.

Types of Cancer:

• There are five main types of cancers according to the type of tissue affected. 
• Cancers are named according to the tissue from which they arise.

i. Carcinoma: 

• Cancer that arise from epithelial tissue covering or lining the body organs is known as carcinoma. 
• It include breast cancer, lung cancer, cancer of stomach, skin cancer. etc.

ii. Sarcoma: 

• Cancer that arises from connective tissue is called sarcoma. 
• It include - 

1. Osteosarcoma - bone tumors 
2. Myosarcoma- muscle tumors  
3. Chondrosarcoma - cancer of cartilage and 
4. Liposarcoma - cancer of adipose tissue.

iii. Lymphoma: 

• Cancer that arises from lymphatic tissue, is called lymphoma. 
• It occurs in the lymphatic nodes, spleen and tissues of immune system.

iv. Leukemia: 

• It is a type of blood cancer in which there is excessive formation of white blood cells (WBCs) or leucocytes in the bone marrow. 
• People suffering from leukemia have very high leucocyte count. 
• The blood contains millions of abnormal immature WBCs or leucocytes that are incapable of fighting infections.
• There are various types of leukemia such as monocytic leukemia, lymphoblastic leukemia etc.

v. Adenocarcinoma: 

• Adenocarcinoma cancer arises in thyroid, pituitary adrenal and other glandular tissues

Causes of Cancer:

• Although, it is still not very clear as to how the cancer is caused, several factors are now known to be cancer- causing i.e. carcinogenic.
• These factors are as follows. 

i. Chemicals : 

• Several chemicals are known to induce cancer. 
• These include nicotine, caffeine, products of combustion of coal and oil. 
• Several polycyclic hydrocarbons, some sex hormone and steroids, if given or secreted in large amounts, may cause cancer. 
• Breast cancer seems to have hormonal relationship. 
• It is more commonly observed in women who avoid breast feeding.

ii. Radiation : 

• The x-rays, gamma-rays cosmic rays, ultra-violet rays etc. are carcinogenic. 
• Incidence of skin cancer is higher in the people working in very sunny areas due to UV radiation in the sunlight.

iii. Viruses : 

• Viruses causing cancer have genes called viral oncogenes (v-onc genes).
• These viruses are also called oncogenic viruses. 
• e.g. EBV(Epstein-barr virus), HPV (Human papiloma virus) etc.

iv. Oncogenes : 

• Several genes called cellular oncogenes (c-onc genes) or proto-oncogenes.
• Have been identified in normal cells which when activated under certain condition could lead to oncogenic transformation of cells.

v. Addiction : 

• Different types addictions likes smoking, chewing of tobacco lead to cancer of mouth, lips and lungs. 
• Alcohol consumption may result in cancer of oesophagus, stomach, intestine and liver.
• Drugs also cause cancer e.g. Marijuana, anaerobic steroids etc.

Treatment of Cancer:

• Cancer treatment consists of combination of a number of therapies which are follows:

i. Chemotherapy: 

• Chemotherapy comprises administration of certain anticancer drugs.
• The anticancer drugs check cell division by inhibiting DNA synthesis or are more toxic to cancerous cell than to normal cells. 
• Chemotherapy may lead to hair loss or anaemia but both get corrected after the treatment is stopped.

ii. Radiotherapy:

• It is used in addition to chemotherapy. 
• In radiotherapy, the basic principle is to bombard the cancerous tissue or cells with the rays from radioactive materials. 
• For treatment, the cancer tissue or cells are exposed to radiations from radioactive materials such as cobalt, iridium and iodine. 
• The rays x-rays gamma rays and charge particles are used to destroy the cancerous tissue or cells but cause minimum damage to the surrounding normal tissue or cells.

iii. Surgery: 

• In surgery, the entire cancerous tissue or cells are removed surgically. 
• It has limited utility. 
• In certain cases such as breast tumor or uterine tumor, the surgery is most effective.
• Other treatments are also given to kill any cancerous cell that may have been escaped in surgery.

iv. Immunotherapy: 

• Tumor cell have been shown to avoid detection and destruction by immune system. 
• Therefore, the patients are given substances called biological response modifiers such as a-interferon which activates their immune system and helps in destroying the tumor.

v. Supportive therapy: 

• Supportive therapy is used to treat symptoms of cancer and side effects of cancer treatments. 
• Objective of this therapy is to improve the quality of life of cancer patient. 
• This therapy varies depending upon condition of individual patient.