Cancer (European Portuguese) or Cancer (Brazilian Portuguese) is a disease characterized by a population of cells that grow and divide without respect the normal limits, invades and destroys adjacent tissues, and may spread to distant locations in the body via a process called metastasis. These malignant properties of cancers differentiate them from benign tumors, which are self-limited in their growth and do not invade adjacent tissues (although some benign tumors are capable of becoming malignant). The cancer can affect people of all ages, but the risk for most cancers increases with increasing age. Cancer causes about 13% of all deaths worldwide, and cancers of the lung, stomach, liver, colon and breast cancer the biggest killers.
Doctors in ancient Egypt (3000 BC) recorded diseases, given their characteristics, could probably be classified as cancer. Hippocrates (377 BC) also described conditions that resembled those cancers of stomach, rectum, breast, uterus, skin and other organs. Therefore, the presence of cancer in humanity has been known for millennia. However, records that describe the cause of death as cancer came into existence in Europe only from the eighteenth century. Since then, there was a steady increase in cancer mortality rates, which seem to become more pronounced after the nineteenth century with the arrival of industrialization. [3]
Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as smoking, radiation, chemicals, or infectious agents. Other types of gene abnormalities can be acquired through errors in DNA replication, or are inherited, and thus present in all cells at birth. The complex interactions between carcinogens and the host genome may explain why only some develop cancer after exposure to a known carcinogen. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly being recognized as important to the process.
Genetic abnormalities found in cancer typically affect two general classes of genes. The cancer-promoting genes, oncogenes are typically activated in cancer cells, giving those cells new properties, such as hyperactive growth and division, protection against programmed cell death, loss of respect for normal tissue boundaries, and the ability to become stable in many tissue environments. The tumor suppressor genes are often inactivated in cancer cells, resulting in loss of normal functions of these cells, as accurate DNA replication, control over the cell cycle, orientation and adhesion in tissues and interaction with protective cells of the immune system.
The cancer is generally classified according to the tissue from which cancer cells originate as well as with normal cell type that most closely resemble. A definitive diagnosis often requires histological examination of biopsy tissue by a pathologist, but initial indications of malignancy can be symptoms or abnormality in the radiographic images. Most can be treated and some cured, depending on the specific type, location and staging. Once diagnosed, the cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. With the development of research, treatments are becoming more specific for different varieties of cancer. Lately there has been significant progress in the development of therapeutic drugs that act specifically on detectable molecular abnormalities in certain tumors while minimizing damage to normal cells. The prognosis for patients with cancer is greatly influenced by the type of cancer, as well as staging the extent of disease. Moreover, the histological grade and the presence of specific molecular markers can also be useful in establishing the prognosis as well as in determining individual treatments.
Doctors in ancient Egypt (3000 BC) recorded diseases, given their characteristics, could probably be classified as cancer. Hippocrates (377 BC) also described conditions that resembled those cancers of stomach, rectum, breast, uterus, skin and other organs. Therefore, the presence of cancer in humanity has been known for millennia. However, records that describe the cause of death as cancer came into existence in Europe only from the eighteenth century. Since then, there was a steady increase in cancer mortality rates, which seem to become more pronounced after the nineteenth century with the arrival of industrialization. [3]
Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as smoking, radiation, chemicals, or infectious agents. Other types of gene abnormalities can be acquired through errors in DNA replication, or are inherited, and thus present in all cells at birth. The complex interactions between carcinogens and the host genome may explain why only some develop cancer after exposure to a known carcinogen. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly being recognized as important to the process.
Genetic abnormalities found in cancer typically affect two general classes of genes. The cancer-promoting genes, oncogenes are typically activated in cancer cells, giving those cells new properties, such as hyperactive growth and division, protection against programmed cell death, loss of respect for normal tissue boundaries, and the ability to become stable in many tissue environments. The tumor suppressor genes are often inactivated in cancer cells, resulting in loss of normal functions of these cells, as accurate DNA replication, control over the cell cycle, orientation and adhesion in tissues and interaction with protective cells of the immune system.
The cancer is generally classified according to the tissue from which cancer cells originate as well as with normal cell type that most closely resemble. A definitive diagnosis often requires histological examination of biopsy tissue by a pathologist, but initial indications of malignancy can be symptoms or abnormality in the radiographic images. Most can be treated and some cured, depending on the specific type, location and staging. Once diagnosed, the cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. With the development of research, treatments are becoming more specific for different varieties of cancer. Lately there has been significant progress in the development of therapeutic drugs that act specifically on detectable molecular abnormalities in certain tumors while minimizing damage to normal cells. The prognosis for patients with cancer is greatly influenced by the type of cancer, as well as staging the extent of disease. Moreover, the histological grade and the presence of specific molecular markers can also be useful in establishing the prognosis as well as in determining individual treatments.
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