Cancer is characterised by uncontrolled proliferation of cells without any differentiation, having ability to invade other tissues or parts of the body.Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. cancer cells appear to have lost this property. As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumors.all tumors are not cancerous. tumors may be benign and malignant.
Benign tumor is a large localised mass of abnormal tissue enclosed in connective tissue which does not invade adjacent tissue.
Malignant tumor is not encapsulated and is capable of invading adjacent tissues,distant sites and it is deadliest cancers
Metastasis is a spread of cancerous cells from one part of the body to other parts through blood, lymph and secondary forms of malignant tumors. Metastasis is the most feared property of malignant tumors.
All types of cancer list are carcinoma, sarcoma, leukemia and lymphoma.
Carcinoma is a cancer of epithelial tissue and their derivatives like mucous membrane ,such as skin cancer or lungs cancer, breast cancer etc. It is list of most aggressive cancers It may spread to other parts of the body, or be confined to the primary location.
Sarcoma is a cancer of primitive mesodermal tissue like connective tissue, bone, muscle, lymph nodes etc.It is the general term for a broad group of cancers that begin in the bones and in the soft tissue
Leukemia is a blood cancer. It involves the increased wbc count (200,000-1000,000/mm) of blood due to increased formation in the blood marrow resulting in decreased erythropoiesis and rbc count.
lymphomas affect the lymphatic system, a network of vessels and nodes that acts as the body's filter.
Causes of cancer
Chemical and physical agents that can cause cancer are called carcinogens. These are Overexposure to ionising radiations like X-rays, UVrays, gamma rays etc which literally punches holes in the DNA, breaking the correct genetic sequences.Chemicals like nicotine, caffeine, steroids, and arsenic air pollutants causing cancers of lungs, brain, breast or blood.Viruses, which include the human papilloma virus (implicated in cervical cancer), the human T cells lymphocytic virus (implicated in lymphoma), and hepatitis B virus (implicated in liver cancer) Oncogenes and tumour suppressor genes.
Cancer-associated genes can be divided into the following
three categories
Genes that induce cellular proliferation, e.g., genes encoding growth factors, growth factor receptors, transcription factors etc.
Genes that inhibit cellular proliferation (tumor suppressor genes).
Genes that regulate programmed cell death (apoptosis).
Possible symptoms of cancer and cancer sign cancer sign
These are:-
A persistent cough or hoarseness in a smoker.
A persistent change in digestive and bowel habits.
A change in a wart or mole.
A lump or hard area in the breast.
Unexpected diminished or lost appetite.
Unexplained low-grade fever.
Unexplained loss of weight.
Any incurable ulcer.
Bleeding in vagina at times other than menstruation.
Non-injury bleeding from the surface of the skin,mouth or any other opening of the body.
Detection and diagnosis of cancer
Techniques such as radiography (use of X-rays),CT Scan (computed tomography), MRI Scan (magnetic resonance imaging) are very useful to detect cancers of the internal organs. Mammography is a radiographic examination of breasts for possible cancer. Bone marrow biopsy and abnormal count of WBCs is used in leukemia.
Treatment of cancer: The common approaches for treatment of cancer are surgery, radiation therapy and immunotherapy