A tumour (also called neoplasm) is the abnormal growth of cells and/or tissues. Tumours are either benign or malignant, and are unregulated by the natural control mechanisms of the body. According to the National Cancer Institute, tumours are classified as leukaemia, non-small cell lung cancers, NCI-H226, CNS tumours, melanoma, ovarian, renal, prostate and breast tumours.
Malignant tumours are spread by metastasis and invasion while benign tumours cannot be spread by either metastasis or invasion. Metastasis (also called metastatic disease or mets) is the ability of cancerous cells to spill, leak or break away from their site of origin (pancreas, prostate, kidney, breast, lung or colon), or primary tumour, and enter the blood and lymphatic vessels. These cancerous cells are deposited within healthy tissues of the body, where they multiply and grow--affecting vital organs. Most malignant cancers are capable of metastasising. Malignant tumours are also spread by invasion--the process in which cancerous cells invade the blood vessels. Benign tumours, on the other hand, grow locally at the site of the original tumour.
Benign tumours are significantly less dangerous than malignant tumours. For instance, melanoma is a type of malignant cancer that is born in the skin and spreads through the bloodstream to other organs, such as the brain or the liver. Benign tumours by themselves are not life threatening, but may result in complications if they press on vital body organs, such as the brain.
The three main types of malignant tumours include leukaemia, sarcomas and carcinomas. Leukaemia is cancer of the bone marrow or blood, which is characterised by an atypical increase in white blood cells. It is classified into acute leukaemia, chronic leukaemia, lymphoblastic leukaemia and myelogenous leukaemia. A sarcoma is a type of malignant cancer that affects connecting tissue cells, such as fat, cartilage and bone cells. Types of sarcomas include leiomyosarcoma, chondrosarcoma and osteosarcoma. Carcinomas are malignant tumours that include squamous cell carcinoma, anaplastic carcinomas, small cell lung carinoma, pleomorphic carcinoma and adenocarcinoma. Types of benign tumours include leiomyomas (muscle tumours), lipomas (fat tissue tumours), neurilemomas (nerve tumours), nodular tenosynovitis (joint tumour) and hemangiomas (skin or internal organ tumours).
Benign tumours are typically treated with surgery, and it is uncommon for the original tumour to reappear. Malignant tumours are treated and managed by chemotherapy, radiation therapy, cryotherapy and surgical excision.
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