Cancer is the name given to a large group of diseases, all of which have one thing in common: cells that are growing out of control. Normally, the cells that make up all of the parts of our bodies go through a predictable life cycle -- old cells die, and new cells arise to take their place. Occasionally, this process goes awry, and cells begin to multiply out of control. The end result is a mass of cells, called a tumor. A benign tumor is one that does not spread, or metastasize to other parts of the body. It is considered noncancerous. A malignant tumor, on the other hand, can spread throughout the body and is considered cancerous. When malignant cells break away from the primary tumor and settle into another part of the body, the resulting new tumor is called either a metastasis or a secondary tumor.
There are several major types of cancers: carcinomas form in the cells that cover the skin or line the mouth, throat, lungs and organs; sarcomas are found in the bones, muscles, fibrous tissues and some organs; leukemia are found in the blood, the bone marrow, and the spleen; and lymphomas are found in the lymphatic system.
Causes of Oncology
Cancer often takes many years to develop. The process typically begins with some disruption to the DNA of a cell, the genetic code that directs the life of the cell. There can be many reasons for disruptions, such as diet, tobacco, sun exposure, reproductive history or certain chemicals. Some cells will enter a precancerous phase, known as dysplasia. Some cells will progress further to the state of carcinoma in situ, in which the cancer cells are restricted to a microscopic site, surrounded by a thick covering and do not pose a great threat.
Eventually, unless the body's own immune system takes care of the wayward cells, a cancer will develop. It may take as long as 30 years for a tumor to go through the entire process and become large enough to produce symptoms.
Symptoms of Oncology
Since cancer can arise from such a wide variety of sites and develop with many differing patterns of spread, there are no clear-cut symptoms. Cancer is unlike many more specific diseases such as heart disease or arthritic disease. The precise nature of symptoms of cancer depends not only on primary site but specifically where the tumor is located in an organ, rate of development and also secondary spread is present or not.
Many primary tumors cause local swelling or lump if they arise at a visible or accessible part of the body, such as a skin, breast, testicle or oral cavity. A typical swelling due to a cancer is initially painless, though ulceration (skin breakdown) can occur, which may then become painful.
Treatment of Oncology
The aim of cancer treatment is to cure the patient and save life. The cases where complete cure is not possible, treatment aims to control the disease and to keep the patient normal and comfortable as long as possible. The treatment of each patient is designed to suit an individual and depends on the age of the patient, stage and type of disease. There may be only one treatment or combination of treatments. There are four main modalities of treatment : Surgery, Radiation therapy, Chemotherapy, hormonetherapy and Immunotherapy. Surgery and radiotherapy aim at eradicating the disease at the primary site (site of origin) of cancer whereas chemotherapy, hormonetherapy and immunotherapy deal with disease which may have spread outside the site of origin of cancer. Surgery is the most important part of the cancer treatment. Surgery attempts to remove cancer cells from the body by cutting away the tumor and any tissues surrounding it which may contain cancer cells. It is a simple, safe and effective method when cancer is small and confined to the site of origin. It is best suited for certain type of cancers such as, breast cancer, head and neck cancers, early cancers of the cervix and lung, many skin cancers, soft tissue cancers and gastrointestinal cancers. Radiotherapy has become the pre-eminent form of cancer treatment since beginning of this century and now it is used for fifty percent of patients. Improvements in radiotherapy equipment, technique and applications, have led to an increasing role both in local treatment and also in its use as a whole-body treatment , as part of bone marrow transplantation techniques for leukaemia and other malignant diseases.
Radiation is a special kind of energy carried by waves or a stream of particles originating from radioactive substances and delivered by special machines. These radioactive x-rays or gamma rays can penetrate the cell wall and damage the nucleus of the cell which prevents growth and division of cells. This also affects the normal cells but these cells recover more fully than cancer cells. Chemotherapy uses drugs which interfere with the growth and division of malignant cells. Once the drugs are administered, they circulate throughout the body. It is advantageous over surgery & radiation for treating cancer that is systemic (spread throughout the body). Chemotherapy is very useful in treating cancers like leukemia, lymphomas, testicular cancer. Chemotherapy can be given as the primary treatment, or following surgery or radiotherapy to prevent reappearance of cancer.
The side-effects of the chemotherapy include nausea, vomiting, hair loss, fever etc. which are temporary and completely reversible. Hormone therapy has limited use in cancer treatment since only a small minority of tumors are hormone sensitive e.g. breast and prostate cancer. This therapy provides systemic means of treatment, i.e. to the whole body, but without the side effects of chemotherapy. In summary, it is misconception that all cancers are incurable. Current methods of treatment are effective for many cancers. A large number of cancer patients are cured and more patients could be cured if their cancers were detected early and treated promptly.