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National Cancer Institute Fact Sheet
    Reviewed: 03/07/2008
Understanding Prognosis and Cancer Statistics: Questions and Answers

Key Points
  • A prognosis gives an idea of the likely course and outcome of a disease (see Question 1).
  • Many factors affect a person’s prognosis, including the type, location, and stage of the disease; the presence of a chromosomal  abnormality or abnormal blood cell counts (for some cancers); and the person’s age, general health, and response to treatment (see Question 2).
  • When predicting the prognosis, doctors sometimes use statistics based on groups of people whose situations are most similar to that of an individual patient (see Question 3).
  • Survival rate is a type of statistic that indicates the percentage of people with a certain type and stage of cancer who survive for a specific period of time after their diagnosis (see Question 3).
  • Doctors cannot be absolutely certain about the outcome for a particular patient. In fact, a person’s prognosis may change over time (see Question 4).
  • The doctor who is most familiar with a patient’s situation is in the best position to discuss prognosis, taking into account the individual characteristics of the patient that can affect the overall situation (see Question 5).
  1. What is a prognosis?

    People facing cancer are naturally concerned about what the future holds. A prognosis gives an idea of the likely course and outcome of a disease—that is, the chance that a patient will recover or have a recurrence (return of the cancer).

  2. What factors affect a patient’s prognosis?

    Many factors affect a person’s prognosis. Some of the most important are the type and location of the cancer, the stage of the disease (the extent to which the cancer has metastasized, or spread), and its grade (how abnormal the cancer cells look and how quickly the cancer is likely to grow and spread). In addition, for hematologic cancers (cancers of the blood or bone marrow) such as leukemias and lymphomas, the presence of chromosomal abnormalities and abnormalities in the patient’s complete blood count (CBC) can affect a person’s prognosis. Other factors that may also affect the prognosis include the person’s age, general health, and response to treatment.

  3. How do statistics contribute to predicting a patient’s prognosis?

    When doctors discuss a person’s prognosis, they carefully consider all factors that could affect that person’s disease and treatment and then try to predict what might happen. The doctor bases the prognosis on information researchers have collected over many years about hundreds or even thousands of people with cancer.

    When possible, the doctor uses statistics based on groups of people whose situations are most similar to that of an individual patient. Several types of statistics might be used to discuss prognosis. Some commonly used statistics are described below:

    • Survival rate indicates the percentage of people with a certain type and stage of cancer who survive for a specific period of time after their diagnosis. For example, 55 out of 100 people with a certain type of cancer will live for at least 5 years, and the other 45 people will not. Survival statistics may further categorize the people who die by cause of death because some will die from unrelated causes. For example, of the 45 people mentioned above, 35 may die from their cancer and 10 may die from other causes.

    • The 5-year survival rate indicates the percentage of people who are alive 5 years after their cancer diagnosis, whether they have few or no signs or symptoms of cancer, are free of disease, or are having treatment. Five-year survival rates are used as a standard way of discussing prognosis as well as a way to compare the value of one treatment with another. It does not mean that a patient can expect to live for only 5 years after treatment or that there are no cures for cancer.

    • Disease-free or recurrence-free survival rates represent how long one survives free of the disease, rather than until death.

    Because survival rates are based on large groups of people, they cannot be used to predict what will happen to a particular patient. No two patients are exactly alike, and treatment and responses to treatment vary greatly.

    The doctor may speak of a favorable prognosis if the cancer is likely to respond well to treatment. The prognosis may be unfavorable if the cancer is likely to be difficult to control. It is important to keep in mind, however, that a prognosis is only a prediction. Again, doctors cannot be absolutely certain about the outcome for a particular patient.

  4. Is it helpful to know the prognosis?

    Cancer patients and their loved ones face many unknowns. Understanding cancer and what to expect can help patients and their loved ones plan treatment, think about lifestyle changes, and make decisions about their quality of life and finances. Many people with cancer want to know their prognosis. They find it easier to cope when they know the statistics. They may ask their doctor or search for statistics such as survival rates on their own. Other people find statistical information confusing and frightening, and they think it is too impersonal to be of use to them.

    The doctor who is most familiar with a patient’s situation is in the best position to discuss the prognosis and to explain what the statistics may mean for that person. At the same time, it is important to understand that even the doctor cannot tell exactly what to expect. In fact, a person’s prognosis may change if the cancer progresses or if treatment is successful.

    Seeking information about the prognosis is a personal decision. It is up to each patient to decide how much information he or she wants and how to deal with it.

  5. What is the prognosis if a patient decides not to have treatment?

    Because everyone’s situation is different, this question can be difficult to answer (see Question 3). Prognostic statistics often come from studies comparing new treatments with best available treatments, not with “no treatment.” Therefore, it is not always easy for doctors to accurately estimate prognosis for patients who decide not to have treatment. However, as mentioned above, the doctor who is most familiar with a patient’s situation is in the best position to discuss prognosis, taking into account individual characteristics of the patient that can affect the overall situation.

    There are many reasons patients decide not to have treatment. One reason may be concern about side effects related to treatment. Patients should discuss this concern with their doctor and cancer nurse. Many medications are available to prevent or control the side effects caused by cancer therapies. Another reason patients might decide not to have treatment is that their type of cancer does not have a good prognosis even when treated. In these cases, patients may want to explore clinical trials (research studies). A clinical trial may offer access to new drugs that may be more promising than the standard treatments available.

    People interested in taking part in a clinical trial should talk with their doctor. Information about clinical trials is available from the National Cancer Institute’s (NCI) Cancer Information Service (CIS) (see below) at 1–800–4–CANCER and in the NCI booklet Taking Part in Cancer Treatment Research Studies, which is available at http://www.cancer.gov/clinicaltrials/Taking-Part-in-Cancer-Treatment-Research-Studies on the Internet. This booklet describes how research studies are carried out and explains their possible benefits and risks. The NCI is a part of the National Institutes of Health. Further information about clinical trials is available at http://www.cancer.gov/clinicaltrials on the NCI’s Web site. The Web site offers detailed information about specific ongoing studies by linking to PDQ®, the NCI’s comprehensive cancer information database. The CIS also provides information from PDQ.

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Related NCI materials and Web pages:

For more help, contact:

NCI's Cancer Information Service
Telephone (toll-free): 1–800–4–CANCER (1–800–422–6237)
TTY (toll-free): 1–800–332–8615
LiveHelp® online chat: https://cissecure.nci.nih.gov/livehelp/welcome.asp


Glossary Terms

abnormal
Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.
blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.
blood cell count
A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called complete blood count and CBC.
bone marrow (bone MAYR-oh)
The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.
cancer (KAN-ser)
A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.
Cancer Information Service
CIS. The Cancer Information Service is the National Cancer Institute's link to the public, interpreting and explaining research findings in a clear and understandable manner, and providing personalized responses to specific questions about cancer. Access the CIS by calling 1-800-4-CANCER (1-800-422-6237), or by using the LiveHelp instant-messaging service at https://cissecure.nci.nih.gov/livehelp/welcome.asp. Also called CIS.
cell (sel)
The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.
chromosome (KROH-muh-some)
Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.
CIS
The CIS is the National Cancer Institute's link to the public, interpreting and explaining research findings in a clear and understandable manner, and providing personalized responses to specific questions about cancer. Access the CIS by calling 1-800-4-CANCER (1-800-422-6237), or by using the LiveHelp instant-messaging service at https://cissecure.nci.nih.gov/livehelp/welcome.asp. Also called Cancer Information Service.
clinical trial
A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical study.
complete blood count
CBC. A test to check the number of red blood cells, white blood cells, and platelets in a sample of blood. Also called blood cell count and CBC.
cure
To heal or restore health; a treatment to restore health.
diagnosis (DY-ug-NOH-sis)
The process of identifying a disease, such as cancer, from its signs and symptoms.
drug
Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.
grade
The grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Grading systems are different for each type of cancer.
hematologic cancer (HEE-muh-tuh-LAH-jik KAN-ser)
A cancer of the blood or bone marrow, such as leukemia or lymphoma.
leukemia (loo-KEE-mee-uh)
Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the bloodstream.
lymphoma (lim-FOH-muh)
Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.
metastasize (meh-TAS-tuh-size)
To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastatic tumor are like those in the original (primary) tumor.
National Cancer Institute
The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. The National Cancer Institute conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the National Cancer Institute Web site at http://www.cancer.gov. Also called NCI.
National Institutes of Health
NIH. A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH.
NCI
NCI, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. It conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the NCI Web site at http://www.cancer.gov. Also called National Cancer Institute.
nurse
A health professional trained to care for people who are ill or disabled.
PDQ
PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.
prognosis (prog-NO-sis)
The likely outcome or course of a disease; the chance of recovery or recurrence.
prognostic factor (prog-NOS-tik FAK-ter)
A situation or condition, or a characteristic of a patient, that can be used to estimate the chance of recovery from a disease or the chance of the disease recurring (coming back).
progression (proh-GREH-shun)
In medicine, the course of a disease, such as cancer, as it becomes worse or spreads in the body.
quality of life
The overall enjoyment of life. Many clinical trials assess the effects of cancer and its treatment on the quality of life. These studies measure aspects of an individual’s sense of well-being and ability to carry out various activities.
recurrence (ree-KER-ents)
Cancer that has recurred (come back), usually after a period of time during which the cancer could not be detected. The cancer may come back to the same place as the original (primary) tumor or to another place in the body. Also called recurrent cancer.
response (reh-SPONTS)
In medicine, an improvement related to treatment.
side effect
A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.
stage
The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.
standard therapy (...THAYR-uh-pee)
In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with standard therapy. Also called standard of care or best practice.
survival rate (ser-VY-vul ...)
The percentage of people in a study or treatment group who are alive for a certain period of time after they were diagnosed with or treated for a disease, such as cancer. The survival rate is often stated as a five-year survival rate, which is the percentage of people in a study or treatment group who are alive five years after diagnosis or treatment. Also called overall survival rate.
symptom
An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.
therapy (THAYR-uh-pee)
Treatment.


Table of Links

1http://cancer.gov/cancertopics/factsheet/Information/clinical-trials
2http://cancer.gov/cancertopics/factsheet/Detection/tumor-grade
3http://cancer.gov/cancertopics/factsheet/Detection/tumor-markers
4http://cancer.gov/cancertopics/factsheet/Detection/laboratory-tests
5http://cancer.gov/cancertopics/factsheet/Detection/staging
6http://cancer.gov/cancertopics/factsheet/Therapy/doctor-facility
7http://cancer.gov/cancertopics/factsheet/support/support-groups
8http://www.cancer.gov/clinicaltrials
9http://www.cancer.gov/clinicaltrials/Taking-Part-in-Cancer-Treatment-Research-S
tudies
10http://www.cancer.gov/cancertopics/takingtime
11http://cancer.gov/cancertopics/wyntk/overview