Cancer is a disease of the body’s cells. It occurs when cells in the body become abnormal and grow out of control. A change which makes the gene faulty is called a mutation. Some special genes, called control genes, instruct the cell to copy its genes correctly, and to divide in an orderly manner. They stop controlling cell division, which is cancer.
Benign Tumors: Tumors arise with great frequency, especially in older animals and humans, but most pose little risk to their host because they are localized and of small size. The surface interaction molecules that hold tissues together keep benign tumor cells, like normal cells, localized to appropriate tissues. A fibrous capsule usually delineates the extent of a benign tumor.
Malignant tumor: In contrast, the cells composing a malignant tumor, or cancer, express some proteins characteristic of the cell type from which it arose, and a high fraction of the cells grow and divide more rapidly than normal. Some malignant tumors remain localized and encapsulated, at least for a time; an example is carcinoma in situ in the ovary or breast. Most, however, do not remain in their original site; instead, they invade surrounding tissues, get into the body’s circulatory system, and set up areas of proliferation away from the site of their original appearance. The spread of tumor cells and establishment of secondary areas of growth is called metastasis; most malignant cells eventually acquire the ability to metastasize. Thus the major characteristics that differentiate metastatic (or malignant) tumors from benign ones are their invasiveness and spread. They are usually less well differentiated than normal cells or benign tumor cells. The presence of invading cells is the most diagnostic indication of a malignancy. Cancer cells can multiply in the absence of growth-promoting factors required for proliferation of normal cells and are resistant to signals that normally program cell death (apoptosis). Both primary and secondary tumors require angiogenesis, the recruitment of new blood vessels, in order to grow to a large mass. Cancer cells, which are closer in their properties to stem cells than to more mature differentiated cell types, usually arise from stem cells and other proliferating cells.
Following are the types of Cancer:
1. Carcinoma: It includes tumors of brain, breast, skin, cervical region. These are derived from epithelial tissue, originating from either ectoderm or endoderm. These occurs as solid tumors, located in the nervous tissue on the body surface or associated glands.
2. Sarcoma: They are the cancers of connective tissues, cartilage, bone or muscles which are mesodermal in origin.
3. The leukemias: A class of sarcomas, grow as individual cells in the blood, whereas most other tumors are solid masses. (The name leukemia is derived from the Latin for “white blood”: the massive proliferation of leukemic cells can cause a patient’s blood to appear milky)
4. Lymphoma: Lymph nodes, bone marrow, liver and spleen produces excessive lymphocytes. Cancer in them are called as lymphomas eg. Hodgkin’s disease.
Benign Tumors: Tumors arise with great frequency, especially in older animals and humans, but most pose little risk to their host because they are localized and of small size. The surface interaction molecules that hold tissues together keep benign tumor cells, like normal cells, localized to appropriate tissues. A fibrous capsule usually delineates the extent of a benign tumor.
Malignant tumor: In contrast, the cells composing a malignant tumor, or cancer, express some proteins characteristic of the cell type from which it arose, and a high fraction of the cells grow and divide more rapidly than normal. Some malignant tumors remain localized and encapsulated, at least for a time; an example is carcinoma in situ in the ovary or breast. Most, however, do not remain in their original site; instead, they invade surrounding tissues, get into the body’s circulatory system, and set up areas of proliferation away from the site of their original appearance. The spread of tumor cells and establishment of secondary areas of growth is called metastasis; most malignant cells eventually acquire the ability to metastasize. Thus the major characteristics that differentiate metastatic (or malignant) tumors from benign ones are their invasiveness and spread. They are usually less well differentiated than normal cells or benign tumor cells. The presence of invading cells is the most diagnostic indication of a malignancy. Cancer cells can multiply in the absence of growth-promoting factors required for proliferation of normal cells and are resistant to signals that normally program cell death (apoptosis). Both primary and secondary tumors require angiogenesis, the recruitment of new blood vessels, in order to grow to a large mass. Cancer cells, which are closer in their properties to stem cells than to more mature differentiated cell types, usually arise from stem cells and other proliferating cells.
Following are the types of Cancer:
1. Carcinoma: It includes tumors of brain, breast, skin, cervical region. These are derived from epithelial tissue, originating from either ectoderm or endoderm. These occurs as solid tumors, located in the nervous tissue on the body surface or associated glands.
2. Sarcoma: They are the cancers of connective tissues, cartilage, bone or muscles which are mesodermal in origin.
3. The leukemias: A class of sarcomas, grow as individual cells in the blood, whereas most other tumors are solid masses. (The name leukemia is derived from the Latin for “white blood”: the massive proliferation of leukemic cells can cause a patient’s blood to appear milky)
4. Lymphoma: Lymph nodes, bone marrow, liver and spleen produces excessive lymphocytes. Cancer in them are called as lymphomas eg. Hodgkin’s disease.
