THE DISEASE

What is Cancer?

Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Not all tumors are cancerous; benign tumors do not spread to other parts of the body. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss and a change in bowel movements. While these symptoms may indicate cancer, they may have other causes. Over 100 cancers affect humans.

Cancers are often described by the body part that they originated in. However, some body parts contain multiple types of tissue, so for greater precision, cancers are additionally classified by the type of cell that the tumor cells originated from.

types of cancer

Carcinoma is a type of cancer that develops from epithelial cells.[1] Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal orectodermal germ layer during embryogenesis.

Carcinomas occur when the DNA of a cell is damaged or altered and the cell begins to grow uncontrollably and becomemalignant. It is from the Greek καρκίνωμα 'karkinoma' meaning sore, ulcer, or cancer, itself derived from karkinos 'crab

Sarcoma (from the Greek σάρξ sarxmeaning "flesh") is a cancer that arises from transformed cells of mesenchymal origin. Thus, malignant tumors made of cancellous bone, cartilage, fat, muscle, vascular, orhematopoietic tissues are, by definition, considered sarcomas. This is in contrast to a malignant tumor originating from epithelialcells, which are termed carcinoma. Human sarcomas are quite rare. Common malignancies, such as breast, colon, and lung cancer, are almost always carcinoma.

Sarcomas are given a number of different names based on the type of tissue that they most closely resemble. For example, osteosarcoma resembles bone, chondrosarcoma resemblescartilage, liposarcoma resembles fat, and leiomyosarcoma resembles smooth muscle.

Lymphoma is a group of blood cell tumors that develop from lymphocytes (a type of white blood cell). The name often refers to just the cancerous ones rather than all such tumors. Signs and symptoms may include enlarged lymph nodes, fever, drenching sweats, unintended weight loss, itching, and feeling tired. The enlarged lymph nodes are usually painless. The sweats are most common at night.

There are dozens of sub types of lymphomas. The two main categories of lymphomas are Hodgkin lymphomas (HL) and the non-Hodgkin lymphomas (NHL).The World Health Organization (WHO) includes two other categories as types of lymphoma: multiple myeloma and immuno pro life rative diseases. About 90% of lymphomas are non-Hodgkin lymphomas. Lymphomas and leukemiasare a part of the broader group of tumors of the hematopoietic and lymphoid tissues.

Leukemia also spelled leukaemia, is a group of cancers that usually begin in the bone marrow and result in high numbers of abnormal white blood cells. These white blood cells are not fully developed and are called blasts or leukemia cells. Symptoms may include bleeding and bruising problems,feeling tired, fever, and an increased risk of infections. These symptoms occur due to a lack of normal blood cells. Diagnosis is typically made by blood tests or bone marrow biopsy.The exact cause of leukemia is unknown. Different kinds of leukemia are believed to have different causes. Both inherited and environmental (non-inherited) factors are believed to be involved.

Germ Cell Tumor (GCT) is a neoplasm derived from germ cells. Germ cell tumors can be cancerous or non-cancerous tumors. Germ cells normally occur inside the gonads (ovary and testis). Germ cell tumors that originate outside the gonads may be birth defects resulting from errors during development of the embryo.

Blastoma is a type of cancer, more common in children, that is caused by malignancies inprecursor cells, often called blasts. Examples are nephroblastoma, medulla blastoma and retino blastoma. The suffix "-blastoma" is used to imply a tumor of primitive, incompletely differentiated (or precursor) cells, e.g., chondroblastoma is composed of cells resembling the precursor of chondrocytes. Blastomas usually occur in children.

Risk factors for Hodgkin lymphoma include infection with Epstein–Barr virus and a history of the disease in the family. Risk factors for common types of non-Hodgkin lymphomas include autoimmune diseases, HIV/AIDS, infection with human T-lymphotropic virus, immuno suppressant medications, and some pesticides. Eating large amounts of red meat may also increase the risk. Diagnosis, if enlarged lymph nodes are present, is usually by lymph node biopsy. Blood, urine, and bone marrow testing may also be useful in the diagnosis. Medical imaging may then be done to determine if and where the cancer has spread. Lymphoma most often spreads to the lungs, liver, and/or brain.

Treatment may involve one or more of the following: chemotherapy, radiation therapy,targeted therapy, and surgery. In some non-Hodgkin lymphomas, an increased amount of protein produced by the lymphoma cells causes the blood to become so thick thatplasmapheresis is performed to remove the protein. Watchful waiting may be appropriate for certain types. The outcome depends on the sub type with some being curable and treatment prolonging survival in most. The five-year survival rate in the United States for all Hodgkin lymphoma sub types is 85%, while that for non-Hodgkin lymphomas is 69%.Worldwide, lymphomas developed in 566,000 people in 2012 and caused 305,000 deaths.They make up 3–4% of all cancers, making them as a group the seventh-most common form. In children, they are the third-most common cancer. They occur more often in the developed world than the developing world.

Risk factors include smoking, ionizing radiation, some chemicals (such as benzene), prior chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four main types of leukemia — acute lymphoblastic leukemia (ALL), acute myeloid leukemia(AML), chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML) — as well as a number of less common types. Leukemias and lymphomas both belong to a broader group of tumors that affect the blood, bone marrow, and lymphoid system, known as tumors of the hematopoietic and lymphoid tissues.

Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy, and bone marrow transplant, in addition to supportive care and palliative care as needed. Certain types of leukemia may be managed with watchful waiting. The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world. The average five-year survival rate is 57% in the United States. In children under 15, the five-year survival rate is greater than 60 to 85%, depending on the type of leukemia. In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return.

In 2012, leukemia developed in 352,000 people globally and caused 265,000 deaths. It is the most common type of cancer in children, with three quarters of leukemia cases in children being the acute lymphoblastic type. However, about 90% of all leukemias are diagnosed in adults, with AML and CLL being most common in adults. It occurs more commonly in the developed world.