cancer

wikipedia.com
Cancer (medical term: malignant neoplasm) is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, and do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.
Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age.[1] Cancer causes about 13% of all human deaths.[2] According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.[3] Cancers can affect all animals.
Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells.[4] These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. The heritability of cancers are usually affected by complex interactions between carcinogens and the host's genome. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly recognized as important.
Genetic abnormalities found in cancer typically affect two general classes of genes. Cancer-promoting 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 established in diverse tissue environments. Tumor suppressor genes are then inactivated in cancer cells, resulting in the loss of normal functions in those cells, such as accurate DNA replication, control over the cell cycle, orientation and adhesion within tissues, and interaction with protective cells of the immune system.
Diagnosis usually requires the histologic examination of a tissue biopsy specimen by a pathologist, although the initial indication of malignancy can be symptoms or radiographic imaging abnormalities. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. As research develops, treatments are becoming more specific for different varieties of cancer. There has been significant progress in the development of targeted therapy drugs that act specifically on detectable molecular abnormalities in certain tumors, and which minimize damage to normal cells. The prognosis of cancer patients is most influenced by the type of cancer, as well as the stage, or extent of the disease. In addition, histologic grading and the presence of specific molecular markers can also be useful in establishing prognosis, as well as in determining individual treatments.

Pesticide Use Linked to Higher Risk of Pre-Cancerous Multiple Myeloma

Investigators from NCI used data from the Agricultural Health Study to refine and expand a relationship between pesticide exposure and risk for multiple myeloma that they had established several years ago. They found that men who used pesticides occupationally, particularly farmers, had a nearly two-fold increased risk of a well-established precursor for multiple myeloma--monoclonal gammopathy of undetermined significance--when compared to men not exposed to pesticides through their job. These findings add support to the hypothesis that pesticides are biologically linked to the development of multiple myeloma.
Multiple myeloma is estimated to be diagnosed in about 20,000 Americans this year and about 10,000 Americans are expected to die of the disease in 2009. This research finding has been published in the journal Blood (available here) and was authored by Ola Landgren and colleagues at NCI as well as researchers at the Mayo Clinic, Rochester, Minn., and the National Institute of Environmental Health Sciences, which along with NCI is part of the National Institutes of Health.