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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).
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- 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).
- 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.
- 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.
- 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.
- 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.
# # #
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
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