Staging Defined
A Natl. Cancer Institute Training Module
http://training.seer.cancer.gov/module_ss2k/intro_staging_defined.html
Current as of 8/2002
What is "Staging?"
The concept of describing disease by stage or extent of disease was introduced
in 1929 by the League of Nations' World Health Organization, now known
as the World Health Organization, WHO. The first primary site so described
was cancer of the cervix.
Staging is a shorthand method for describing disease. A coded format,
such as a numerical system with increasing values meaning more involvement
or severity, allows electronic analysis of cases with similar characteristics.
A simple definition for staging is the grouping of cases into broad categories
based on extent of disease.
For cancer, extent of disease is a detailed description of how far the
tumor has spread from the organ or site of origin (the primary site).
Extent of disease is an anatomic categorization using descriptors to group
individual cases in relation to the human body. In other words, extent
of disease is an anatomic classification, in which cases are grouped based
on specific anatomic criteria. Classification is an orderly arrangement
showing relationships among groups.
The relationship between staging, extent of disease, and classification
is:
* Extent of disease is a type of classification (based on human anatomy) and pertains to an individual case;
* Staging is coded shorthand or a notation describing disease in more general terms.
By staging, characteristics about a case (precise extent
of disease information) can be grouped into categories. Thus staging translates
extent of disease classification about individual cancers into groups
that can be studied or evaluated for prognostic significance, whereas
classification does not necessarily imply a prognosis.
Elements to be considered in any staging system are the primary tumor
site, tumor size, multiplicity (number of tumors), depth of invasion and
extension to regional or distant tissues, involvement of regional lymph
nodes, and distant metastases.
Why Staging?
http://training.seer.cancer.gov/module_ss2k/intro_why_staging.html
Just imagine that every one of us spoke a different language! We wouldn't
be able to understand each other and nothing could be communicated or
be done. The importance of staging lies in the fact that it provides medical
professionals with an excellent tool of communication about a disease
so that they can describe it better and then do something about it. With
such a common language, physicians, surgeons, pathologists, radiation
therapists, oncologists, cancer researchers, and medical practitioners
in other specialized fields can communicate effectively about cancer and
find ways to prevent and treat the disease.
In the form of coded format that is easily understood universally, staging
standardizes cancer data into categories which can be compared locally,
nationally, and internationally. The exchange of standardized data between
cancer researchers facilitates the continuing investigation, ("research")
of cancer. The comparison of treatment results of cancer becomes meaningful
only if it is based on a common criteria for extent of disease.
Cancer treatment decisions are influenced, in part, according to the stage
of disease, since it is important for the medical practitioner to adequately
assess the extent of cancer in order to treat the disease in the most
appropriate manner. Based on a detailed knowledge of the extent of the
disease, cancer specialists can make recommendations about the chances
of being cured by surgery alone, the type of surgery that will give the
patient the best possible outcome, or additional treatments (radiation,
hormone or chemotherapy).
Staging is also used to indicate prognosis or survival. Data from historical
sources can provide an estimate of the expected survival rate for a particular
cancer with a corresponding extent of disease. In addition to stage, histology,
grade of the tumor, age, sex, race, and the efficacy of therapy play a
part in determining the patient's prognosis and quality of survival.
As an important component of cancer statistics, staging also plays an
important role in the evaluation of screening programs.
Information obtained from the entire health information record is to be
used to accurately assign a stage for a cancer case.
Major Staging Systems
http://training.seer.cancer.gov/module_ss2k/intro_major_staging_systems.html
Staging of cancer has evolved over many years. Many groups have developed
different staging systems. Some cover all cancer sites. Others are limited
to particular ages, histologies, sites, study groups, or medical specialties.
The major staging systems in use in cancer registries include: Summary
Staging, American Joint Committee on Cancer (AJCC) TNM Staging System,
and SEER Extent of Disease (EOD). Since Summary Staging is the topic of
this training module, it will be covered in detail in the following sections.
However, a brief description of the other two common staging systems are
presented here for your information.
American Joint Committee on Cancer (AJCC/UICC TNM) Staging System
The concept of a classification scheme that would encompass all aspects
of cancer in terms of primary tumor (T), regional lymph nodes(N), and
distant metastasis (M) was first introduced by the Union Internationale
Centre le Cancer (UICC), in 1958 for worldwide use. Staging schemes
were developed by AJCC (the American contingency of the UICC) to be consistent
with the practice of medicine in the United Stages and used the basic
premise of the TNM system: cancer of similar histology or site of origin
share similar patterns of growth and extension. It is identical to the
classification of the Union Internationale Contre le Cancer (UICC).
The AJCC staging scheme is based on the evaluation of the T, N, and M
components and the assignment of a stage grouping. The T element designates
the size and/or invasiveness of the primary tumor. The N component designates
the presence or absence of tumor in the regional lymph nodes. The M component
identifies the presence or absence of distant metastases, including the
spread to (or involvement of ) lymph nodes that are beyond regional lymph
node drainage.
The general rules for the AJCC staging system are defined in the AJCC
Manual for Staging of Cancer. For further information about AJCC, visit
their Web site at http://www.cancerstaging.org.
SEER Extent of Disease Coding (EOD)
SEER EOD coding includes schemes for all sites and histologies of cancer.
It consists of a ten-digit code. It incorporates three digits for the
size of the primary tumor, two for the extension of the tumor, and one
more as a general code for lymph node involvement. Four more digits are
used after these six: two digits for the number of pathologically positive
regional lymph nodes and two more digits for the number of regional lymph
nodes that are pathologically examined. The code is based on clinical,
operative, and pathologic diagnoses of the cancer. For some sites and
histologies where size of tumor is irrelevant, the size field is used
to collect other information such as HIV status, etc.. Refer to the SEER
EOD manual, SEER Extent of Disease, for further details.
Site Specific Staging Systems
Unlike the above major staging systems that encompass all tumor types,
the following staging systems are site specific.
The Dukes staging system is a classic albeit dated method for describing
extent of disease for colorectal cancer. It was created by Sir C.E. Dukes,
a British pathologist, in 1929. Simpson and Mayo modified Dukes' scheme
for colon cancer in 1939. Further modifications were made by Astler, Coller,
and others. The Dukes staging system and its modifications are still in
use by many clinicians today. In 1998, the TNM system was modified to
correspond with the Dukes system.
The Whitmore-Jewett Staging system, sometimes called the Jewett Staging
System is a popular staging classification system prostate cancer. The
system was created in 1975 and it classifies all prostatic cancers into
one of four stages. These may be numbered 1-4 or distinguished by the
letters A-D. Later, it was modified by the AJCC and UICC to include subcategories.
It was created by The American Urological Association (AUA). However,
urologists are abandoning both the Whitmore-Jewett and the AUA staging
schemes and adopting the AJCC staging schemes.
Some other existing staging schemes include: Jewett and Strong for bladder
(later modified by Marchall and was referred to as Jewett-Marshall Staging);
FIGO staging system describing for female reproductive organ tumors; the
Ann Arbor classification, a staging scheme commonly used for the staging
of lymphomas; Breslow's microstaging and Clark's level of invasion, two
classification schemes for melanoma, and many others.
Summary Staging
http://training.seer.cancer.gov/module_ss2k/ss_defined.html
Summary staging is the most basic way of categorizing how far a cancer
has spread from its point of origin. Summary staging has also been called
General Staging, California Staging, and SEER Staging. Summary staging
uses all information available in the medical record; in other words,
it is a combination of the most precise clinical and pathological documentation
of the extent of disease.
Summary staging is a required data item for facilities and central registries
participating in the National Program of Cancer Registries (NPCR) of the
Centers for Disease Control and Prevention (CDC). Many cancer registries
report their data using summary stage because the staging categories are
broad enough to measure the success of cancer control efforts and other
epidemiologic efforts. However, even though summary staging is used frequently
in cancer registries, it is not always understood by physicians. Rather
physicians are more likely to understand AJCC TNM staging.
Summary staging is based on the theory of cancer growth. Intraepithelial,
noninvasive, or non-infiltrating cancer is described as in "situ."
In situ tumors fulfill all microscopic criteria for malignancy except
invasion of the basement membrane of the organ. A "localized"
tumor is confined to the organ of origin without extension beyond the
primary organ. "Regional extension" of tumor can be by direct
extension to adjacent organs or structures or by spread to regional lymph
nodes. If the cancer has spread to parts of the body remote from the primary
tumor, it is recorded as "distant" stage. Sometimes there is
insufficient information to assign a stage, such as in cases without thorough
diagnostic workups or cases in which there is ambiguous or contradictory
information.
Significance of Changes
http://training.seer.cancer.gov/module_ss2k/ss2k_major_changes.html
A Manual with Rules, Definitions, and Standard NAACCR Codes
The new SEER Summary Staging Manual - 2000 is a true manual (rather than
just a "guide" like the old Summary Staging Guide - 1977). The
SEER Summary Staging Manual – 2000 contains instructions, definitions,
and detailed descriptions. The new manual also contains the actual standard
NAACCR stage codes.
ICD-O-2/3 Site Codes
The new SEER Summary Staging Manual - 2000 contains the site codes that
are listed in ICD-O-2 (and subsequently, ICD-O-3, because there were no
site code changes in ICD-O-3). This should help in locating the correct
scheme within the manual. For example, to stage a carcinoma of the nasopharynx
, NOS (site code = C11.9 in ICD-O-2/3), one would need to know that the
numbers "470-473, 478-479" that are found at the top of the
Nasopharynx scheme pages of the Summary Staging Guide - 1977 (SSG77) are
actually old ICD-O-1 site codes with the leading '1' removed and the subsite
decimal point removed. Now, with the new SEER Summary Staging Manual -
2000, users simply look up the site code (with the nasopharynx, NOS example,
the site code = C11.9) in ICD-O-2/3 and then use that site code to find
the scheme directly in the SEER Summary Staging Manual - 2000. Of course,
users could also choose to use the Table Of Contents in the front of the
SEER Summary Staging Manual - 2000.
A Scheme for Every Primary Site
Every primary site now has a scheme in SEER Summary Staging Manual - 2000.
This alone is a MAJOR improvement over the old SSG77. It was often frustrating,
not to mention difficult, to stage a cancer case arising in a primary
site for which there was no scheme in SSG77. Users should have used the
"non-specific staging scheme" found on page 2 of the SSG77 -
however, it is well known that this was not a routine and uniform practice.
Those days are behind us now because each and every primary site has a
scheme in the new SEER Summary Staging Manual - 2000.
European Eponymic Standard
The word 'eponym' means 'to name upon.' So, for instance, Dr. Ewing was
the first person to describe the bone tumor that is now known as "Ewing's
sarcoma" - that "Ewing's sarcoma" is an eponymic term.
It is literally 'named upon Dr. Ewing.' The same holds true for Paget's
disease, Waldeyer's ring, Hodkin's lymphoma, etc. The European standard
for eponyms (the 'European Eponymic Standard') is to drop the apostrophe
's' ('s). Since the international ICD-O-3 committee decided to adopt the
European Eponymic Standard, the sites (and morphologies) listed in ICD-O-3
do not include the apostrophe 's' if they are eponymic terms. The same
European Eponymic Standard was adopted in the new SEER Summary Staging
Manual - 2000.
Detailed Instructions and Illustrations
Again, another major enhancement to the manual is the inclusion of detailed
instructions. Further, detailed pertinent anatomical illustrations have
also been included. Both the detailed instructions and the detailed pertinent
illustrations should make summary staging an easier and more pleasant
experience.
New "Time Rule"
There is a new "time rule" to be used when staging with the
SEER Summary Staging Manual 2000.
The new "time rule" is:
Summary stage should include all information available through completion
of surgery(ies) in the first course of treatment or within four months
of diagnosis in the absence of disease progression, whichever is longer.
Note that the new "time rule" is really a "time and information"
rule rather than just a "time" rule, per se.
This new "time rule" differs from the "two month rule"
used in SSG77. This change alone will not allow time trend analyses on
stage prior to 2001 diagnoses and those diagnosed on or after January
1, 2001.
For Use: Starting with 2001 Diagnoses
It should be noted that the new SEER Summary Staging Manual - 2000 is
for use with cancer cases diagnosed on January 1, 2001 and forward. The
SEER Summary Staging Manual - 2000 carries the "2000" in its
name because the manual was largely created in the year 2000. Do not use
the SEER Summary Staging Manual - 2000 to stage cases unless they were
diagnosed on, or after, January 1, 2001.
Unit Review
In Unit One, we learned the concept of staging. In brief, staging is a
shorthand method for describing extent of disease. It is a common language
developed by medical professionals to communicate information about cancer
to others.
The related terms such as "extent of disease" and "classification"
and their relationship to staging were also briefly discussed. Classification
is an orderly arrangement showing relationships among groups. Extent of
disease is a type of classification and pertains to an individual case.
Staging translates extent of disease classification about individual cancers
into groups that can be studied or evaluated for prognostic significance.
Several reasons for staging mentioned in this section are:
* Staging is a guide in making decisions about treatment: to help decide what treatment would most favorably alter the natural course of disease;
* Staging is a factor in evaluating prognosis of a particular case by comparing it to similar cases; and
* Staging is a mechanism for comparing the results of different therapeutic procedures or data generated by (observed by) different institutions.
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