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Every day, without our even being aware of it, the cells that make up our body are growing, dividing and/or producing more cells as needed in order to keep us healthy. But sometimes, this process goes haywire; certain cells lose their normal control mechanism and start growing out of control. This is what happens with cancer.
Tumors and cancer are not always the same thing. The National Cancer Institute (NCI) says a tumor is a mass of extra tissue. Some tumors can be felt or seen externally on the body. Some tumors are internal and can be picked up via an imaging scan. NCI says tumors can be benign or malignant.
According to the American Cancer Society (ACS), most cancers form as a tumor. But some do not. For example, the cancer cells of leukemia involve the blood and blood-forming organs, but do not actually form a mass or tumor.
Cancer can begin in any part of the body, and is categorized by the type of tissue where it starts.
Cancers are usually identified by their site of origin. That means that the type or name of the cancer is the original site where the cancer developed, even if the cancer has spread to other parts of the body. For example, even if breast cancer has spread to the liver, it would still be considered breast cancer, not liver cancer. (Read about "Liver Cancer")
In some cases, ACS says the cancer first appears in one or more of the sites to which it has spread, and the original site where the cancer developed is not known. These cancers are called Cancers of Unknown Primary. Sometimes, additional tests can determine where the cancer started, and the cancer would be renamed for its site of origin. Other times, the primary site may never be known. ACS says that even if the source is never discovered, treatment can still be successful.
In many cases, the exact cause of the cancer is unknown. However, we do know that there are some things that can increase the risk of different types of cancer. (Read about "Reduce Cancer Risks") Among the things that can affect a person's risk of developing cancer, according to the American Cancer Society are:
In addition, cancer can be more likely to develop when the immune system isn't functioning properly. (Read about "Primary Immunodeficiency" "Immune System Glossary" "The Immune System")
The American Cancer Society says many forms of cancer are treated most successfully when caught early. This is why regular screenings, such as Pap tests, mammograms, PSA tests, etc., are so important. (Read about "Cancer Check-ups" "Mammograms")
If a screening produces a suspicious result, or if a doctor suspects cancer for some other reason, additional tests can be done, for example, blood or urine tests or imaging scans.
However, for cancers, the way to make a definitive diagnosis is a tissue diagnosis with a biopsy. Biopsy is the removal of cells or tissues for examination by a specialist physician called a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. Examination of suspicious cells through a biopsy helps the doctor determine if the cells are malignant (cancerous) or benign. (Read about "Biopsy")
If cancer is present, a doctor must determine what type of cancer it is, how fast it is growing, and whether or not it has invaded nearby healthy tissue or spread to other parts of the body. This helps the doctor determine at what stage the cancer is, and how best to treat it.
Staging is the term used to describe the extent or severity of an individual's cancer. A cancer's stage depends on different factors, including its location, its size, whether lymph nodes have been affected and whether or not the cancer has spread. (Read about "The Lymph System")
NCI says different tests can be used to help determine a cancer's stage. These include blood and urine tests; imaging tests such as x-rays, CT scans, MRI, PET and ultrasound (Read about "X-rays" "CT Scan - Computerized Tomography" "MRI - Magnetic Resonance Imaging" "PET - Positron Emission Tomography" "Ultrasound Imaging"); pathology reports from the biopsy; and surgical reports. Knowing a cancer's stage helps to determine the best way to treat it. (Read about "Cancer Treatments")
When a cancer spreads to another part of the body, it is called metastasis. Researchers say one of the most important things required for metastasis to occur is the growth of a new network of blood vessels. This process of forming new blood vessels is called angiogenesis. Angiogenesis is a normal biological process. For example, angiogenesis is necessary for the repair or regeneration of tissue during wound healing. Tumor angiogenesis, however, is different. NCI says tumor angiogenesis is the growth of a network of blood vessels that penetrates into cancerous growths, supplies them with nutrients and oxygen and removes waste products. NCI says tumor angiogenesis starts with cancerous tumor cells releasing molecules that send signals to activate genes in the host tissue that, in turn, make proteins to encourage growth of new blood vessels. Certain molecules can either activate or inhibit angiogenesis. Studies are now examining the effectiveness of drugs aimed at inhibiting angiogenesis in specific cancers. (Read about "Clinical Studies")
Below, in alphabetical order, is a list of individual cancers and tumors. You can learn more about each of them by following the appropriate link.
Acute lymphocytic leukemia (ALL): see Leukemia Acute myeloid leukemia (AML): see Leukemia Acute nonlymphocytic leukemia (ANLL): see Leukemia Adenocarcinoma, esophagus: see Esophagus Cancer Adenocarcinoma, vaginal: see Vaginal Cancer Adenocarcinoma, bladder: see Bladder Cancer Anaplastic thyroid cancer: see Thyroid Cancer Angiosarcoma, liver: see Liver Cancer Astrocytomas: see Brain Tumors Basal cell cancer: see Skin Cancer Bladder cancer: see Bladder Cancer Bone cancer: see Bone Cancer Bone cyst, unicameral: see Bone Tumors - Benign Brain stem gliomas: see Brain Tumors Brain tumors: see Brain Tumors Breast cancer: see Breast Cancer Cervical cancer: see Cervical Cancer Chest tumors: see Chest Tumors Children's cancer: see Cancer & Children Cholangiocarcinoma, liver: see Liver Cancer Chondrosarcoma: see Bone Cancer Chronic lymphocytic leukemia (CLL): see Leukemia Chronic myeloid leukemia (CML): see Leukemia Colon cancer: see Colorectal Cancer Colorectal cancer: see Colorectal Cancer Craniopharyngiomas: see Brain Tumors Ductal carcinoma: see Breast Cancer Endometrial cancer: see Uterine Cancer Ependymomas: see Brain Tumors Epithelial carcinoma: see The Ovaries Esophagus cancer: see Esophagus Cancer Ewing's sarcoma: see Bone Cancer Eye cancer: see Eye Cancer Fibrous dysplasia: see Bone Tumors - Benign Follicular thyroid cancer: see Thyroid Cancer Gastric cancer: see Stomach Cancer Germ cell tumors, brain: see Brain Tumors Giant cell tumor: see Bone Tumors - Benign Head cancer: see Head & Neck Cancers Hepatoblastoma,: see Liver Cancer Hepatocellular carcinoma: see Liver Cancer Hodgkin's disease: see Lymphoma Hypopharyngeal cancer: see Head & Neck Cancers Intraocular cancers: see Eye Cancer Kidney cancer: see Kidney Cancer Laryngeal cancer: see Head & Neck Cancers Leukemia: see Leukemia Lip cancer: see Oral Cancer Liver cancer: see Liver Cancer Lobular carcinoma: see Breast Cancer Lung cancer: see Lung Cancer Lymphoma: see Lymphoma Malignant melanoma: see Skin Cancer Medullary thyroid cancer: see Thyroid Medulloblastomas: see Brain Tumors Melanoma: see Skin Cancer Mesothelioma: see Mesothelioma Metastatic squamous neck cancer with occult primary: see Head & Neck Cancers Multiple myeloma: see Multiple Myeloma & Plasmacytoma Myelodysplastic Syndromes: see Myelodysplastic/Myeloproliferative Diseases Myeloma: see Multiple Myeloma & Plasmacytoma Myeloproliferative Disorders: see Myelodysplastic/Myeloproliferative Diseases Nasal cavity cancer: see Head & Neck Cancers Nasopharyngeal cancer: see Head & Neck Cancers Neck cancer: see Head & Neck Cancers Neuroblastoma: see Cancer & Children Neuroectodermal tumors: see Brain Tumors Non-Hodgkin's lymphoma: see Lymphoma Oligodendrogliomas: see Brain Tumors Oral cancer: see Oral Cancer Orbital cancers: see Eye Cancer Oropharyngeal cancer: see Head & Neck Cancers Osteoid osteomas: see Bone Tumors - Benign Osteosarcoma: see Bone Cancer Ovarian cancer: see The Ovaries Paget's disease of breast: see Breast Cancer Pancreatic cancer: see Pancreatic Cancer Papillary thyroid cancer: see Thyroid Cancer Paranasal sinus cancer: see Head & Neck Cancers Parathyroid cancer: see Parathyroid Glands Penile cancer: see Penile Cancer Pineal region tumors: see Brain Tumors Pineoblastoma: see Brain Tumors Pineocytoma, brain: see Brain Tumors Plasmacytoma: see Multiple Myeloma & Plasmacytoma Prostate cancer: see The Prostate Rectal cancer: see Colorectal Cancer Renal cell carcinoma: see Kidney Cancer Retinoblastomas: see Cancer & Children Rhabdomyosarcomas: see Cancer & Children Salivary cancer: see Head & Neck Cancers Skin cancer: see Skin Cancer Squamous carcinoma, vaginal: see Vaginal Cancer Squamous cell carcinoma, skin: see Skin Cancer Squamous cell carcinoma, bladder: see Bladder Cancer Squamous cell carcinoma, esophagus: see Esophagus Cancer Stomach cancer: see Stomach Cancer Testicular cancer: see Testicular Cancer Thyroid cancer: see Thyroid Cancer Tracheal tumors: see Tracheal Tumors Transitional cell carcinoma, bladder: see Bladder Cancer Unicameral bone cyst: see Bone Tumors - Benign Urethral Cancer: see Urethral Cancer Uterine cancer: see Uterine Cancer Vaginal Cancer: see Vaginal Cancer Wilms' tumor: see Kidney Cancer |
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