Cancer is a group of over 200 different diseases in which abnormal cells multiply uncontrollably, destroying body tissues or functions. Cancer can form in almost any place in the body and each cancer is named for the tissue type or organ in which it begins.
The most common types of cancer (other than basal cell skin cancer and squamous cell skin cancer) are breast cancer, lung cancer, prostate cancer, colon and rectal cancer, and melanoma.
Cancer has various symptoms and is treated in different ways depending on the type. Treatments include surgery, chemotherapy, radiation, and immunotherapy.
One in two men and one in three women are expected to develop cancer (not including skin cancer) over the course of a lifetime.
For a normal cell to become a cancer cell, a series of genetic mutations needs to take place. Environmental or medical radiation, carcinogens, infections, genetic makeup, can raise your risk of mutations. Some substances and exposures directly damage DNA, while lifestyle factors (e.g. poor diet or lack of physical activity) can increase cancer risk by decreasing immune defenses. Recent data shows that the metastatic process is mainly caused by epigenetic factors.
Whether or not nicotine directly causes cancer remains unclear, but it’s well established that it’s an addictive ingredient in tobacco products. Research also suggests that nicotine may play a role in accelerating cancer growth. Smoking tobacco or using smokeless tobacco products exposes you to cancer-causing substances and can weaken the immune system, making it harder to fight the disease.
Cancer cells can divide uncontrollably and may locally invade or spread at distance and affect important organs, such as the lungs or liver, or interfere with body functions and systems that are essential for survival. Cancer cells are also good at evading the immune system and can go undetected by the body’s built-in defenses.
Most types of solid cancer have four stages. Stage 1 is the least advanced and stage 4 is the most advanced with the worst prognosis. A common system that is used to determine the stage of solid tumors is the TNM system. It assigns values after tests have evaluated the primary tumor (T value), whether or not it has spread to lymph nodes (N value), and whether or not it has spread to other areas of the body (M value).
Things you can do to help reduce your risk of cancer are to quit or avoid smoking, limit alcohol, exercise regularly, use sun protection, eat a healthy diet high in fruits and vegetables and low in red meat, practice safe sex, and check your home for radon to see if you need a radon mitigation system.
They can contribute to a cancer diagnosis, but, in general, are not used to definitely diagnose. Tests may include a complete blood count, a blood chemistry profile, tumor markers, and circulating tumor DNA (currently used only for research purposes). In some forms of blood cancer, other tests like flow cytometry, immunoelectrophoresis, and cytogenetic analysis are used.
Most cancers are related to gene mutations that are acquired and are not inherited. However, in 5% to 10% of cases, cancer is related to a family cancer syndrome that can be inherited. Inherited family syndromes are often mutations in tumor suppressor genes that control how quickly cells divide and when they die.
Carcinomas are the most common category of malignant solid tumors, accounting for 85% to 95% of cancers. They form in epithelial cells, which are in skin and line the body’s cavities and organs. The other category are hematological malignancies that account for approximately 10% of cancers and sarcomas, which occur in connective tissue, and account for 1% of cancers in adults and 15% cancers in children.
Chemotherapy uses medications to treat cancer. These drugs can interfere with rapid cell division and reduce the size of tumors. Chemotherapy agents may be injected or taken orally. Common side effects may include hair loss, bone marrow suppression, and nausea.
The processes cells use to repair DNA damage. Cells have mechanisms to check the DNA before replicating, but when these mechanisms fail, it can lead to mutations and may predispose you to cancer. The activity of DNA repair genes can also influence how effective therapies, such as chemotherapy and radiation, may be in treating cancer.
Immunotherapy refers to treatments for cancer that target the immune system. Examples of immunotherapies include immune checkpoint inhibitors, which are drugs that bind to natural checkpoints of the immune system so that it may focus more intensely on fighting the cancer, and monoclonal antibodies, which are lab-created antibodies that are designed to bind to specific targets on cancer cells.
A tumor that is malignant means it has cancerous cells and may invade locally and spread to other areas of your body. A tumor that is benign means it is noncancerous and won’t invade locally or spread at distance. To determine if a group of cells is malignant or benign, a biopsy (sample) may be taken and analyzed.
When cancer spreads from its primary location to another location in the body. Cancers can metastasize to almost anywhere, but common locations include lymph nodes, bones, brain lungs, and liver. Recent studies show that approximately 67% of cancer deaths are attributable to metastatic cancer.
Radiation (also called radiotherapy) is a cancer treatment that uses high doses of radiation to destroy cancer cells or shrink cancer tissues . Radiation may be given as external beam radiation therapy in which radiation is delivered to a targeted part of the body from the outside, or via internal radiation therapy in which radioactive material is injected or implanted into the body.
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