CANCER: Types of tumours, Types of cancer, Causes of Cancer, Symptoms of cancer, Treatment of cancer

 

CANCER

Cancer is caused due to uncontrolled mitotic division of cells (known as cancer cells) which invade and destroy the surrounding tissues. Normally, the cells in the human body grow in a well regulated way. But when cancer sets in, a group of these cells start multiplying irregularly and form tumours (the term usually applied to an abnormal growth of tissue). Cancer refers to the group of diseases characterised by the uncontrolled multiplication of abnormal cells in the body. If such multiplication of cells takes place within a vital organ or tissue, normal functions of such organ, or tissue is impaired and this may produce fatal results.

Types of tumours :

A tumour may be a benign or a malignant one.

(a) Benign tumour : When tumour does not destroy the tissue in which it originates or does not spread to the distant parts of the body (i.e. it is localised), then it is known as the benign tumour. Such type of tumour can be cured easily. It is usually surrounded by a fibrous capsule. Benign tumours usually do not cause death.

(b) Malignant tumour : When a tumour destroys the tissue in which it originates or spreads to distant parts of the body (i.e., not localised), it is known as the malignant tumour. Such tumour is not cured easily and may cause death.

Types of cancer :

Cancer may be

(i) Carcinoma (malignant tumour in the epithelial tissue), 

(ii) Sarcoma (malignant tumour of connective tissue) 

(iii) Leukemia (in which the bone marrow produces an increased number of leucocytes), and 

(iv) Lymphoma (malignant tumour in the lymph node). 

Further, the sarcoma may again be of fibrous tissue (called fibrosarcoma) or of bone (called osteosarcoma). Carcinomas occur in the epithelial tissues, which cover the body (e.g., skin) and those forming the inner linings of breast, respiratory and gastro-intestinal tracts, the endocrine glands and of urinogenital systems. Sarcomas develop in the connective tissues including fibrous tissues, adipose or fatty tissues, muscles, blood vessels, bone and cartilage. Rarely a cancer develops in both epithelial and connective tissue and is called a carcinosarcoma. Leukemia is caused when the bone marrow and other blood forming organs produce increased number of certain types of leucocytes. Lymphoma is a cancer of lymphoid tissues. It is caused when the immune cells of the body become cancerous and multiply uncontrollably in a lymph node.

Causes of Cancer :

1. Cigarette smoking or chewing tobacco cause lung cancer. Beedis are twice as dangerous as cigarettes in causing oral cancer.

2. Skin cancer may be caused in the waist region due to tightly worn saris and dhotis. 'Kangri under the dress causes abdominal cancer in Kasmiri people. These are due to irritation of the skin.

3. Oral cancer may be caused due to ill-fitting of teeth in the jaws.

4. Excessive exposure of skin to sunlight may sometimes cause cancer.

5. Certain chemicals like abestos, nicotine, caffein etc., may induce cancer in the body.

6. Some injuries, if remain for a long time in the body, may cause cancer.

7. Radiation is known to be associated with some bone sarcomas and leukemia.

8. Some cancers are believed to be of viral origin, For Example, Burkitt's lymphoma, affecting the jaw bones, is caused by a virus named Epstein-Barr virus. Similarly, the genital hopes affecting the female genital system is caused by a virus.

Symptoms of cancer : 

Following symptoms are generally marked in a patient suffering from cancer

1. Presence of persistent lump or thickening anywhere in the body.

2. A sore, if formed, does not heal up.

3. In females there occurs unusual uterine bleeding and discharge.

4. There is hoarseness of voice and difficulty in swallowing.

5. There occurs sudden and rapid change in size and appearance of wart or mole.

6. There is change in bowel habits.

7. Remarkable loss of body weight.

Caner can occur to persons of any age group, but the incidence is higher in persons over 50 years of age. Certain types of cancers are hereditary. They are the eye-retinoblastoma in children. Certain other cancers like cancer of kidney in children is congenital. Other hereditary cancers are those in the stomach and colon.

Treatment of cancer :

More than 85% of cancers to-day are curable if treated in early stage. Treatment depends on the type of tumour, the site of the primary tumour and the extent of spread. The general methods of treatment are surgical removal, radiation and chemotherapy. A new cancer may appear at the same place or in another part of the body after being cured once. Therefore, a patient with a past history of cancer should be re-examined at an interval of every six months.

What are Difference Between Cancer cells and Normal Cells? 

Cancer cells are very different from normal cells. For example, cancer cells:

• It grows when there is no signal for growth. Normal cells only grow when they receive a signal.

• Ignore signals that normally cause cells to stop dividing or die (a process known as programmed cell death or apoptosis).

• It penetrates the environment and spreads to other parts of the body. Normal cells stop growing when they meet other cells, and most normal cells do not move.

• Guide the blood vessels to grow into tumors. These blood vessels supply oxygen and nutrients to the tumor and remove waste products from the tumor.

• It hides from the immune system. The immune system usually removes damaged or abnormal cells.

• The immune system helps cancer cells survive and grow. For example, some cancer cells convince immune cells to defend the tumor rather than attack it.

• It accumulates many changes in chromosomes, such as: B. Cloning and removal of parts of the chromosome. Some cancer cells have twice as many chromosomes.

• It depends on a variety of nutrients from normal cells. In addition, some cancer cells generate energy from nutrients differently than most normal cells. This allows cancer cells to grow faster.

How does cancer develop?

Cancer is a genetic disorder. In other words, it is caused by changes in genes that control how cells work, in particular how they grow and divide.

Cancer-causing genetic changes can occur for the following reasons:

• Errors arising from cell division.

• DNA damage is caused by chemicals in cigarette smoke and harmful substances in the environment, such as ultraviolet rays from the sun.

• They are inherited from our parents.

            The body usually gets rid of cells with damaged DNA before they become cancerous. However, the body's ability to do this decreases with age. This is one of the reasons why you are at a higher risk of developing cancer in old age.

        Every human cancer has a unique combination of genetic changes. As the cancer continues to grow, new changes will occur. Even within the same tumor, cells can have different genetic changes.

Types of genes that cause cancer

• Genetic changes that contribute to cancer usually involve three main types of genes: protooncogenes, tumor suppressor genes, and DNA repair genes. These changes are sometimes referred to as "drivers" of cancer.

• Protooncogenes are involved in normal cell growth and division. However, when these genes change in a certain way or become more active than usual, they can become cancer-causing genes (or oncogenes) that allow cells to survive and survive when they are not supposed to grow.

• Tumor suppressor genes are also involved in the regulation of cell growth and division. Cells with certain changes in tumor suppressor genes can divide uncontrollably.

• DNA repair genes are involved in repairing damaged DNA. Cells with mutations in these genes are prone to additional mutations in other genes and chromosomal changes, such as duplications and deletions of parts of the chromosome. Together, these mutations can make cells malignant.

• As scientists learn more about the molecular changes that cause cancer, they discovered that multiple mutations occur in several types of cancer. There are many cancer therapies today that target gene mutations found in cancer. Some of these treatments can be used by anyone with cancer who has a target mutation, regardless of where the cancer started.

when cancer spreads

• Cancer that has spread from where it first formed to other parts of the body is called metastatic cancer. The process by which cancer cells spread to other parts of the body is called metastasis.

• Metastatic cancer includes cancer cells of the same type and name as the original cancer or primary cancer. For example, breast cancer that forms metastatic tumors in the lungs is metastatic breast cancer, not lung cancer.

• Under the microscope, metastatic cancer cells usually look exactly like the original cancer cells. In addition, metastatic and primary cancer cells usually share some common molecular characteristics, such as the presence of certain chromosomal changes.

• In some cases, treatment can help prolong the life of people with metastatic cancer. In other cases, the primary goal of metastatic cancer treatment is to curb the growth of the cancer or to relieve the symptoms caused by the cancer. Metastatic tumors can cause serious harm to the body, and most people who die from cancer die from metastatic disease.