Cancer stages
Defining the cancer precisely is the first step in deciding how to treat it.
Your experience with cancer won’t
be exactly the same as anyone else’s,
either physically or emotionally. But
your cancer itself will have certain
recognizable characteristics that your
doctors can identify and use to determine
which treatments to recommend.
Two of the most important characteristics
are the cancer’s stage and grade.
A common language
Medical professionals measure cancer
by its stage, which is based on an
assessment of the size of the primary
tumor, whether it has spread, and,
if so, how far. Because an accurate
diagnosis is so important to effective
treatment, they might use physical
exams, imaging, lab tests, a biopsy,
an analysis of your body’s fluids, and
surgery in various combinations in
the staging process.
When they’ve identified your
cancer’s stage, your medical team
has a precise way to communicate
with you, one another, and with
other health professionals about your
treatment options and prognosis.
Knowing the stage of the cancer is
a useful tool for you as well, making
it easier to find precise information
and learn from the experience of other people who have faced a
similar situation.
 |
| Stage |
|
Definition |
|
| Stage 0 |
Early cancer that is
present only in the layer of cells in which it began (carcinoma in situ) |
|
| Stage I Stage II Stage III |
The higher the number,
the greater the tumor
size and/or the more
extensive the spread
of the cancer to nearby
lymph nodes and/or
adjacent organs |
|
| Stage IV |
The cancer has spread
to another organ of
the body |
|
TNM: Center stage
Cancer staging has evolved over
time, using a variety of classification
systems. For the past 50 years, however,
most doctors
have come to rely on
what’s known as
the TNM system.
TNM classifies
cancer using three
categories: T (tumor), N (lymph
nodes), and M
(metastasis).
T measures the
primary tumor and
the extent to which
it has spread into
neighboring tissues. N gauges whether
and how much the
cancer has spread
into the regional,
or nearby, lymph
nodes. M records
whether the cancer
has metastasized,
or spread, to a
distant area of
the body.
Your oncologist
assigns each of
these categories a
number that can
range from 0 to 4, such as T3 or N1.
If one of the letters is followed by an
X rather than a number, it means an
evaluation of that element hasn’t
been possible.
Next, the three elements are
combined to give the cancer’s overall
stage, which is expressed as 0 to IV.
For example, the reading T2-N1-M0
might define a particular cancer as
stage II.
Stage cues
The same combination of TNM
factors doesn’t always indicate the
same stage for primary tumors that
occur in different locations — for
example, what’s stage I for one cancer
is stage II for another. Generally
speaking, the higher the stage, the
more advanced the cancer is.
Tumor grades
In addition to the tumor’s size and
location, doctors use its grade to
identify the treatment options they believe are most appropriate. Tumor
grading, which is a complex system
that considers a number of factors
that vary from one type of cancer to
another, classifies cancer cells by two
criteria — how different from normal
cells of the same type they look under
a microscope and how rapidly they
are likely to grow and spread.
In general, pathologists who
analyze cancerous cells assign a grade
from 1 through 4, though certain
cancers, including prostate and
breast cancer, use different grading
systems. A lower grade indicates
cells that are similar in appearance
to healthy cells, can be expected to
grow relatively slowly, and tend to
respond to treatment. A higher
grade means the cells are more
abnormal and growth is likely to
be more aggressive.
Your doctor can explain the role
grading plays in diagnosing the particular
type of cancer you have and
determining potential treatments.
Other parts of the picture
The science of
cancer diagnosis and
treatment has grown
more sophisticated
in recent years, and
there are factors that
staging and grading,
as important as they
are, don’t take into
account. Cancers are
now identified not only
by location, size, and
shape, but by elements
including molecular
biomarkers and
hormone levels. This
additional information
makes your diagnosis
even more exact and
allows your treatment
options to be more
personalized.