Cancer Terms

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  • Absolute risk

    The difference between two risks, usually smaller than a relative risk.

  • Acute

    Refers to symptoms that start and worsen quickly but do not last over a long time.

  • Adjuvant therapy

    Treatment given after the main treatment to reduce the chance of cancer coming back by destroying any remaining cancer cells. It usually refers to chemotherapy, radiation therapy, hormone therapy, and/or immunotherapy given after surgery.

  • Americans with Disabilities Act (ADA)

    A federal (national) law that protects people with disabilities from discrimination. It requires employers to make reasonable accommodations in the workplace for qualified individuals with a disability. Learn more from the U.S. Department of Labor.

  • Appeal

    Asking your insurance company to reconsider its decision to deny payment for a service or treatment. You have the right to ask your insurance company to conduct a full and fair review of its decision, known as an internal review. If the company still denies payment after considering your appeal, the Affordable Care Act allows you to have an independent review organization decide whether to uphold or overturn the plan’s decision, usually called an external review.

  • Associated costs

    Costs that are related to a cancer diagnosis but not specifically due to medical care given to treat the disease; also called non-medical costs. Transportation and childcare during treatment are two common associated costs for people with cancer.

  • Average/mean

    The middle value of a set of numbers, calculated by adding all of the values and dividing by the number of values in the set.

  • Benign

    Refers to a tumor that is not cancerous. The tumor does not usually invade nearby tissue or spread to other parts of the body.

  • Biopsy

    The removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. Learn more about biopsy.

  • Bone marrow

    The soft, spongy tissue found in the center of large bones where blood cells are formed.

  • Bone marrow transplant

    A medical procedure in which diseased bone marrow is replaced by healthy bone marrow from a volunteer donor. Learn more about bone marrow transplantation.

  • Cancer

    A group of more than 100 different diseases that can begin almost anywhere in the body, characterized by abnormal cell growth and the ability to invade nearby tissues. Learn more about the basics of cancer.

  • Carcinoma

    Cancer that starts in skin or tissues that line the inside or cover the outside of internal organs.

  • Case manager

    A health care professional, often a nurse with experience in cancer, who helps coordinate the care of a person with cancer before, during, and after treatment. At a medical center, a case manager may provide a wide range of services for patients that may include managing treatment plans, coordinating health insurance approvals, and locating support services. Insurance companies also employ case managers.

  • Cells

    The basic units that make up the human body.

  • Chemoprevention

    The use of natural, synthetic (made in a laboratory), or biologic (from a living source) substances to reverse, slow down, or prevent the development of cancer. Learn more about chemoprevention.

  • Chemotherapy

    The use of drugs to kill cancer cells. Learn more about chemotherapy.

  • Chronic

    Refers to a disease or condition that persists, often slowly, over a long time.

  • Claim

    A request made to an insurance company to pay for services covered by a patient’s policy.

  • Clinical significance

    An assessment that a research finding will have practical effects on patient care.

  • Clinical trial

    A research study that tests new treatments and/or prevention methods to find out whether they are safe, effective, and possibly better than the current standard of care (the best known treatment). Learn more about clinical trials.

  • Co-insurance

    The percentage of health care costs an insured patient pays after meeting a health care plan's yearly deductible. For example, an 80/20 co-insurance rate means that the insurance company pays 80% of approved health care costs, and the patient pays the remaining 20% of costs out-of-pocket.

  • Co-pay

    A set fee, in dollars, that an insurance provider requires a patient to pay each time care is received. For example, a visit to the oncologist may cost a patient $30 each time; the insurance provider pays the rest of the visit's costs. The amount of the co-pay is set by the insurance provider, not the doctor's office.


    Consolidated Omnibus Budget Reconciliation Act. A federal law that allows employees in danger of losing health insurance under certain circumstances, such as leaving a job or reducing their hours, to pay for and keep their insurance coverage for a limited time.

  • Cohort

    A group of individuals who share a common experience, exposure, or trait and who are under observation in a research study.

  • Complementary medicine

    A diverse group of treatments, techniques, and products that are used in addition to standard cancer treatments. Learn more about types of complementary therapies.

  • Confidence interval

    A measure of the number of times out of 100 (similar to a percentage) that test results will be within a specified range. It is a measurement used to indicate the reliability of an estimate.

  • Confounding variable

    A factor in a scientific study that wasn’t addressed that could affect the outcome of the study, such as smoking history in a study of people with cancer.

  • Control group

    A group of individuals who do not receive the treatment being studied. Researchers compare this group to the group of individuals who do receive the treatment, which helps them evaluate the safety and effectiveness of the treatment.

  • Coverage

    The benefits and services an insurance company will pay for as part of an insurance policy.

  • Cure

    To fully restore health. This term is sometimes used when a person's cancer has not returned for at least five years after treatment. However, the concept of “cure” is difficult to apply to cancer because undetected cancer cells can sometimes remain in the body after treatment, causing the cancer to return later, called a recurrence. Recurrence after five years is still possible.

  • Deductible

    The amount of approved health care costs an insured patient must pay out-of-pocket each year before the health care plan begins paying any costs.

  • Disability insurance

    Insurance that provides an income on either a short-term or a long-term basis to a person with a serious illness or injury that prevents the person from working.

  • Disease-free survival (DFS)

    The measure of time after treatment during which no sign of cancer is found. This term can be used for an individual or for a group of people within a study. This term is usually used in the context of scientific research.

  • Endpoint

    The results measured at the end of a study to see whether the research question was answered.

  • Essential health benefits

    A set of services that an insurance plan is required to provide to patients. There can be no dollar limits each year on the cost that insurance pays for essential health benefits. According to the Affordable Care Act, plans offered in small group and individual markets must provide items and services in at least 10 categories for the plan to be certified and offered in the health care exchanges. Benefit categories include emergency services, preventive wellness and chronic disease management, and prescription drugs. More information is available at

  • Event-free survival (EFS)

    The measure of time after treatment that a group of people in a clinical trial has not had cancer come back or get worse. This term is also usually used in the context of scientific research.

  • Family and Medical Leave Act (FMLA)

    This federal law offers specific protections for employees during medical leave (when the employee is ill) and family leave (when the employee must care for a spouse, child, or parent who is ill). Learn more from the Department of Labor.

  • Fee-for-service

    This is a type of private health insurance in which a person visits a doctor, submits a claim form, and the insurance plan pays the bill using a co-insurance structure. Deductibles are common.

  • Follow-up care

    Medical examinations and tests the doctor recommends after the active treatment period. This care is used to monitor a patient’s recovery and check for signs of recurrence.


    Health Insurance Portability and Accountability Act. This is a set of national rules that help protect the privacy of a patient's personal medical information, provide patients with access to their medical records, and help people with health problems, such as cancer, get health insurance for themselves and their family members. Learn more from the U.S. Department of Health and Human Services.

  • HMO

    Health Maintenance Organization; a type of private health insurance. In an HMO, a person chooses a primary care doctor from an approved list called the network. Specialist care must be approved by that primary care doctor, called a referral.

  • Hormone therapy

    Treatment that removes, blocks, or adds hormones to destroy or slow the growth of cancer cells. It is also called hormonal therapy or endocrine therapy.

  • Imaging test

    A procedure that creates pictures of internal body parts, tissues, or organs to make a diagnosis, plan treatment, find out whether treatment is working, or observe a disease over time.

  • Immunotherapy

    A type of cancer treatment designed to boost the body's natural defenses to fight the cancer. It uses materials made either by the body or in a laboratory to improve, target, or restore immune system function. It may also be called biologic therapy. Learn more about immunotherapy.

  • In situ

    In place. Refers to cancer that has not spread to nearby tissue, also called non-invasive cancer.

  • In-network care

    Health care providers or facilities that are part of an HMO or PPO plan's approved list or network are considered “in network.” In general, in-network care costs patients less than out-of-network care.

  • Incidence

    The number of new instances of a disease or condition in a particular population during a specific period. Learn more about statistics used to estimate risk and recommend screening.

  • Insurance cap

    The amount of money an insurance plan will pay in total benefits. Once a patient's medical bills reach the total, or cap, the plan will no longer provide coverage. Both lifetime and annual caps were eliminated under the Affordable Care Act. For more information read the section summarizing this law or visit

  • Integrative medicine

    A combination of medical treatments for cancer and complementary therapies to help manage the symptoms and side effects of cancer. Learn more about integrative medicine.

  • Invasive cancer

    Cancer that has spread outside the layer of tissue in which it started and has the potential to grow into other tissues or parts of the body, also called infiltrating cancer.

  • Laboratory test

    A procedure that evaluates a sample of blood, urine, or other substance from the body to make a diagnosis, plan treatment, check whether treatment is working, or observe a disease over time.

  • Late effects

    Side effects of cancer treatment that occur months or years after a diagnosis of cancer because of the related treatments, such as chemotherapy, radiation therapy, or surgery. Learn more about the long-term side effects of cancer treatment.

  • Leukemia

    A cancer of the blood. Leukemia begins when normal white blood cells change and grow uncontrollably. 

  • Lifetime risk

    The probability of developing a disease or dying from that disease across a person’s lifetime.

  • Localized cancer

    Cancer that is confined to the area where it started and has not spread to other parts of the body.

  • Long-term care insurance

    Insurance that helps people with long-lasting illnesses or disabilities pay for non-medical daily services and care that ordinary health plans don't cover, such as help with eating, bathing, and dressing. Depending on the plan, care can be given in the home or outside the home.

  • Lymphatic system

    A network of small vessels, ducts, and organs that carry fluid to and from the bloodstream and body tissues. Through the lymphatic system, cancer can spread to other parts of the body.

  • Lymphoma

    A cancer of the lymphatic system. Lymphoma begins when cells in the lymph system change and grow uncontrollably. Sometimes a tumor is formed.

  • Mass

    A lump in the body.

  • Median

    The middle value in a range of measurements ordered by value.

  • Medicaid

    This is a type of government health insurance for people with low incomes who meet certain conditions. Medicaid is jointly funded by the federal and state governments, but each state operates its program individually (including deciding who can receive Medicaid benefits for that state). Learn more at

  • Medicare

    This is a type of health insurance provided by the federal government for people 65 or older, as well as for some people with disabilities. Medicare is divided into four parts: Parts A, B, C, and D. Part A covers in-patient hospital care. Part B provides financial coverage using premiums, deductibles, and a co-insurance structure for other medical expenses, such as doctor visits. Medicare Advantage plans, or Part C, are insurance plans managed by private, approved companies. Part D provides prescription drug coverage. Learn more at

  • Metastasis

    The spread of cancer from the place where the cancer began to another part of the body. Cancer cells can break away from the primary tumor and travel through the blood or the lymphatic system to the lymph nodes, brain, lungs, bones, liver, or other organs.

  • Mortality rate

    The number of deaths in a particular population during a specific time.

  • Neoadjuvant therapy

    Treatment given before the main treatment. It may include chemotherapy, radiation therapy, or hormone therapy given before surgery to shrink a tumor so that it is easier to remove.

  • Non-essential benefits

    Services provided by an insurance plan that are outside the “essential benefits” category. Patients may be responsible for some or all of these costs.

  • Odds ratio

    A comparison of whether the likelihood of an event is similar between two groups; a ratio of 1 means it is equally likely between both groups.

  • Oncologist

    A doctor who treats cancer and provides medical care for a person diagnosed with cancer. The five main types of oncologists are medical, surgical, radiation, gynecologic, and pediatric oncologists. Learn more about the types of oncologists.

  • Oncology

    The study of cancer.

  • Oncology Nurse

    A nurse who specializes in caring for people with cancer.

  • Open enrollment

    Specific dates where eligible individuals are able to select or change to a new health care plan. Once this time ends, you may need to wait until the next open enrollment period, usually a year later, to join a health care plan, unless you qualify for a special enrollment period. Find additional information at Medicare participants can go to to learn about Medicare open enrollment. If you have private insurance, talk with a health insurance plan representative to learn more.

  • Out-of-network care

    Health care providers or facilities that are not part of an HMO or PPO plan's approved list or network are considered “out of network.” Out-of-network care often costs patients more than in-network care and may involve a deductible and require pre-approval for certain services.

  • Out-of-pocket costs

    Any expense not covered by insurance that a patient must pay.

  • Outcome

    A measurable result or effect.

  • Palliative care

    Palliative care is any form of treatment that concentrates on reducing a patient’s symptoms or treatment side effects, improving quality of life, and supporting patients and their families. It may also be called supportive care. Learn more about palliative care.

  • Pathologist

    A doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

  • Patient navigator

    A person, often a nurse or social worker, who helps guide patients, survivors, families, and caregivers through the health care system. Navigators offer numerous services including arranging financial support, transportation, and childcare during treatment; coordinating care among several doctors; and providing emotional support.

  • Patient Protection and Affordable Care Act

    Often called “health care reform,” this is a 2010 federal law that changed certain rules regarding health insurance coverage in the United States. Learn more from the Department of Health and Human Services.

  • Placebo

    An inactive drug or treatment in a clinical trial. Find out more about the current use of placebos in cancer clinical trials.

  • Plan

    Insurance benefits your employer, union, or other group provides to pay for health care services.

  • Polyp

    A growth of normal tissue that usually sticks out from the lining of an organ, such as the colon.

  • Power of attorney (POA), financial

    A legal document that allows a person to select another person to act on their behalf on financial matters. Learn more about a power of attorney.

  • PPO

    Preferred Provider Organization. This is a type of private health insurance in which a person has access to a network of approved doctors, called in-network doctors. In PPOs, patients typically do not need a referral for specialist care.

  • Pre-existing condition

    A medical condition that a person already has when enrolling in a new health plan. Since 2014, insurance plans cannot deny coverage or charge people extra because of a pre-existing condition. Learn more from the Department of Health and Human Services.

  • Precancerous

    Refers to cells that have the potential to become cancerous. Also called pre-malignant.

  • Precertification

    The process of requesting approval from an insurance company for specific services before they happen, such as a treatment, procedure, or hospital stay; also called pre-approval. Many hospitals and clinics have precertification coordinators, patient navigators, or case managers who help patients with cancer through this process.

  • Predisposition

    A tendency to develop a disease that can be triggered under certain conditions. For example, although a genetic predisposition to cancer increases a person's risk of developing cancer, it is not certain that the person will develop it. Learn more about genetics.

  • Premium

    The amount a person or company pays each month to keep insurance coverage.

  • Primary cancer

    Describes the original cancer.

  • Prognosis

    Chance of recovery; a prediction of the outcome of a disease. Learn more about survival statistics used to estimate a patient’s prognosis.

  • Progression-free survival (PFS)

    The length of time during and after treatment that the cancer does not grow or spread further. This term is often used in the context of scientific research.

  • Protocol

    A formal, written action plan for how a clinical trial will be carried out. It states the goals and timeline of the study, who is eligible to participate, what treatments and tests will be given and how often, and what information will be gathered.

  • Provider

    A doctor, health care professional, or health care facility that has been licensed, certified, or accredited as required by state law.

  • Radiation therapy

    The use of high-energy x-rays or other particles to destroy cancer cells. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. When radiation treatment is given using implants near the cancer cells, it is called internal radiation therapy or brachytherapy. Learn more about radiation therapy.

  • Reasonable and customary fees

    The average cost for health services in a geographic area that insurance plans use to decide how much they will pay for those services. If a doctor's fees for a service are higher than average, the patient must pay the difference.

  • Recurrence

    Cancer that has returned after a period during which the cancer could not be detected. “Local recurrence” means that the cancer has come back to the same general area where the original cancer was located. “Regional recurrence” refers to cancer that has come back in the lymph nodes or other tissues near the original cancer site, usually by direct spread. “Distant recurrence” refers to cancer that has come back and has spread to other parts of the body, usually by traveling through the lymph system or bloodstream. Learn more about dealing with cancer recurrence.

  • Regimen

    A treatment plan that includes expected treatments and procedures, medications and their doses, the schedule of treatments, and how long the treatment will last.

  • Rehabilitation

    Services and resources that help a person with cancer obtain the best physical, social, psychological, and work-related functioning during and after cancer treatment. Find out more about rehabilitation.

  • Relative risk

    Compares the risk of disease between two groups of people.

  • Relative survival

    The amount of time after treatment that a person with cancer lives, excluding all other causes of death but cancer. Learn more about survival statistics.

  • Remission

    The disappearance of the signs and symptoms of cancer but not necessarily the entire disease. The disappearance can be temporary or permanent.

  • Sarcoma

    A cancer that develops in the tissues that support and connect the body, such as fat and muscle. Learn more about sarcoma.

  • Screening

    The process of checking whether a person has a disease or has an increased chance of developing a disease when the person has no symptoms.

  • Secondary cancer

    Describes either a new primary cancer (a different type of cancer) that develops after treatment for the first type of cancer, or cancer that has spread to other parts of the body from the place where it started (see metastasis, above).

  • Social Security Disability Insurance and Supplemental Security Income

    These are two national programs that assist people with disabilities. Each has specific medical requirements that a person must meet before getting these benefits. Both programs are administered by the Social Security Administration. Learn more at

  • Social worker

    A professional who helps patients with cancer and their family members cope with everyday tasks and challenges before, during, and after treatment. Social workers, who may work for a hospital, a service agency, or a local government, can help address financial problems, explain insurance benefits, provide access to counseling, and more.

  • Specialist care

    Health care given by a doctor who has been trained in treating a specific type of health problem or specific group of people. For instance, an oncologist is a doctor who specializes in treating cancer.

  • Staging

    A way of describing cancer, such as where it is located, whether or where it has spread, and whether it is affecting the functions of other organs in the body. Learn more about stages of cancer.

  • Standard of care

    Care that experts agree or guidelines show is the most appropriate and/or effective for a specific type and stage of cancer.

  • Surgery

    The removal of cancerous tissue from the body through an operation. Learn more about cancer surgery.

  • Survivorship

    This term means different things to different people. Two common definitions include having no disease after the completion of treatment and the process of living with, through, and beyond cancer. Learn more about cancer survivorship.

  • Survivorship care plan

    A personalized schedule of follow-up examinations and tests that the doctor recommends after a patient’s active treatment period ends. This may include regular physical examinations and/or medical tests to monitor the patient’s recovery for the coming months and years. It may also be called a follow-up care plan; it is often used in conjunction with a treatment summary (see below). Develop a survivorship care plan with your doctor using ASCO forms.

  • Targeted therapy

    Treatment that targets specific genes, proteins, or other molecules that contribute to cancer growth and survival. Learn more about targeted therapy.

  • Treatment Summary

    A written summary of the therapies that the patient had during the active treatment period. This is often used in conjunction with a survivorship care plan (see above) to help monitor a survivor’s long-term health. Use cancer treatment summary forms with your doctor to keep track of the cancer treatment you received.

  • Tumor

    A mass formed when normal cells begin to change and grow uncontrollably. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Also called a nodule or mass.