Staging of Cancer
– Its Usefulness and Limitations
Clinical Staging
of Breast Cancer – The Implications of Inaccuracy
Reynaldo O. Joson, MD, MScSurg
March 8, 2003
Nowadays, in practically all patients with breast cancer as
well as cancer in other parts of the body, the stage of the cancer is a common
query and information sought for and discussed by patients, their relatives,
and health professionals.
What is staging of cancer?
How is the staging of cancer being done?
Are the results of staging the same all throughout the
course of detection and management of the cancer?
What is the usefulness of staging?
What are the limitations of staging?
Why can’t the staging be 100% accurate in determining the extent of growth and spread of the cancer?
Why can’t the staging be 100% accurate in determining the prognosis of the cancer?
Considering the limitations of staging, should it be
discarded or are there efforts to continually improve its accuracy?
What are the implications of inaccurate staging using
breast cancer as an example?
What is the difference between symptom-directed and
routine metastatic work-up in patients with cancer? What is the preferred
approach in doing diagnostic procedures for staging purposes?
What is the status of practice of staging of cancer in
the Philippines?
What are recommendations on the practice of staging of
cancer in the Philippines?
Nowadays, in practically all patients with breast cancer as well as cancer in other parts of the body, the stage of the cancer is a common query and information sought for and discussed by patients, their relatives, and health professionals.
What is staging of cancer?
Staging of cancer is a way of determining the extent of growth and spread of the cancer.
How is the staging of cancer being done?
Before, there are myriads of systems of staging of cancer. Nowadays, the staging system has somewhat been standardized to the use of three elemental parameters, the tumor (T), the node (N), and the distant metastasis or spread (M), constituting the so-called TNM staging system.
Using the TNM staging system, there are usually four stages, I, II, III, and IV, with stage IV usually representing the most advanced extent and spread of the cancer and stage I, the least advanced. Stage IV usually has evidence of distant metastasis or spread (M). Stage I usually has no spread to the adjacent lymph node (N) and distant parts of the body (M). The size of the primary cancer (T) is usually small, usually less than 2 cm.
Staging the cancer is usually and can be done at different times in the course of detection and management of the cancer. Thus, initial staging is done upon detection of the cancer or upon consultation with a cancer specialist. The initial staging done by the cancer specialist using tools of interview (gathering of symptom data), physical examination (gathering of sign data), with or without laboratory diagnostic procedures, constitutes the so-called clinical staging. Subsequent staging after the clinical staging may be categorized as surgical staging, in which the staging is done in the course of an operative procedure; pathological staging, in which the staging is done after a microscopic examination of specimens removed from body parts; staging at the time of recurrence of the cancer after a period of remission; and staging at time of autopsy after a patient dies.
Are the results of staging the same all throughout the
course of detection and management of the cancer?
Usually they are not. They usually change, one, as a result of progression of the cancer and two, as a result of use of more direct diagnostic procedures used in the subsequent staging.
If the cancer progresses, then the stage will be higher in the next staging
determination.
If the patient is in remission, the stage during the last treatment is the one that counts and is upheld. A stage is not reversed to an earlier stage by treatment.
Results from clinical staging, surgical staging, pathological staging, and autopsy staging are usually different from each other, though they may be the same at times. If an autopsy staging is done, then this is usually taken as the final staging of the cancer of a particular patient. Before the demise of a cancer patient, the clinical staging later refined by a surgical staging (if done) and pathological staging (if done) is the one that counts and is upheld.
What is the usefulness of staging?
Staging of cancer is useful as a guide to treatment as well as for prognostication.
In terms of guide to treatment, for example, stage I and stage II are usually treated with the goal to cure whereas stage III and stage IV are usually treated with the goal just to palliate. There may be specific treatment recommendations for each stage of the cancer.
In terms of prognostication (survival), stage IV carries the worst prognosis whereas stage I the best.
What are the limitations of staging?
Staging is not and cannot be 100% accurate all the time in
terms of determination of extent of growth and spread of the cancer, that is,
the determination of the TNM, as well as in terms of prognostication.
Why can’t the staging be 100% accurate in determining the extent of growth and spread of the cancer?
Even with the most
skilled and experienced cancer specialists and the most sophisticated
diagnostic methods available at present, here and abroad, the determination of
the extent of growth and spread of the cancer cannot be 100% accurate all the
time. This is explained by the
following factors:
1. Inherent limitations of the cancer specialists and
the diagnostic procedures. For example,
a tumor less than 1-cm in its greatest diameter is usually not detectable by
palpation by even the most experienced cancer specialists and by even the most
sophisticated laboratory diagnostic procedures.
2. Variability of presentation and behavior of
cancers. For example, one usually
expects symptoms of distant metastasis (M) in patients with huge cancer-tumor
or T under the TNM staging system.
However, there are times that these patients are asymptomatic. If such be the situation, then chances are,
the M under a symptom-directed clinical staging system will be erroneously
classified as negative M or negative for metastasis.
Why can’t the staging be 100% accurate in determining the prognosis of the cancer?
This can be explained by
the variability of behavior of cancers leading to the saying that no two
cancers are the same. At the moment,
although there are attempts to look for laboratory parameters to predict the behavior
of a particular cancer, the exact behavior is usually determined by its course
over a period of time. If it is fast
growing and recurs soon after treatment, say, a year or two, then the behavior
is considered to be fast and therefore, carries a poorer prognosis than one
which is slow growing (such as stationary in growth over 5 years) and has not
recurred, say, 5 years after treatment.
If one looks at
statistics on survival rates per stage of cancers, one will see that survival
rates decrease with increasing stage and, to emphasize the point that staging
has limitations in determining the prognosis, that even with stage I cancer,
there is no 100% survival rate.
Considering the limitations of staging, should it be
discarded or are there efforts to continually improve its accuracy?
Despite its limitations, staging of cancer is still useful as a guide to treatment as well as prognostication in the majority of instances where it is utilized. It should not be discarded and there must be efforts on the part of the cancer specialists to continually improve its accuracy.
In the Philippines, there is a group of cancer specialists led by those from the Department of Surgery of Ospital ng Maynila Medical Center (OMMC) who have looked into this problem of inaccuracy of clinical staging. Below is an abstract of a paper “Reducing the discrepancy between clinical and pathological tumor and node staging in patients with breast cancer”:
“Literature has shown a
significant discrepancy rate between clinical and pathological tumor and node
staging in patients with breast cancer. A multicenter cooperative and
collaborative action research study (MCCCARS) was established to look into this
issue in the Philippines. An initial retrospective study confirmed the presence and
estimated the extent of discrepancy.
The root causes of discrepancy were identified as absence of a
structured training for surgeon-examiner and absence of an agreed protocol
between pathologists and surgeons on how to examine and report tumor and nodal
status. Thus, a structured training for
surgeon-examiner with the use of a report card and a memorandum of
understanding between pathologists and surgeons were formulated and
implemented. Evaluation showed the
strategies to be effective and easy to implement. This study will be used as basis to institutionalize the
strategies in reducing the discrepancy of clinical and pathological tumor and
node evaluation in patients with breast cancer.
What are the implications of inaccurate staging using breast cancer as an example?
Discrepancy between clinical and pathological TNM staging in patients with breast cancer certainly has a negative impact in management, particularly in the choice of primary treatment as well as in the advice of patients on extent of cancer prior to treatment. Different clinical stages of breast cancer have corresponding different primary treatment approaches. A patient with an actual clinical stage II who is erroneously categorized as clinical stage III will be erroneously treated as one with clinical stage III rather as one with clinical stage II. Nowadays, with the extensive public health information in trimedia and Internet, patients with breast cancer and their relatives would usually ask what stage they are in prior to treatment. An erroneous clinical staging may be a cause of unnecessary alarm in those with overstaging; a source of unwarranted rejoice in those with understaging, and definitely, a potential factor for patient’s dissatisfaction and complaint.
What is the difference between symptom-directed and routine metastatic work-up in patients with cancer? What is the preferred approach in doing diagnostic procedures for staging purposes?
To check the presence of
distant metastasis (M) in a patient with cancer as part of a staging process,
at present there are two approaches that are being used by cancer specialists
(surgical oncologists, medical, pediatric, and radiation oncologists).
A symptom-directed
metastatic work-up (SDMW) is an approach in which the work-up is done only when
there are symptoms suggestive of a metastatic probability and the type of
diagnostic procedure selected is dictated by the nature of the symptoms, such
as imaging of the bone for bone metastasis in a cancer patient with bone pain.
On the other hand, a
routine metastatic work-up (RMW) is an approach in which the work-up is done
even if a cancer patient has no symptom suggestive of a metastasis. The basis for the work-up is the presence of
metastatic possibility. In RMW, there
is usually a battery of laboratory diagnostic procedures being done, which can
cost as much as PhP 20,000.
Considering the extremely
low yield of routine metastatic work-up, as low as 1-2%, and considering the
high cost, a symptom-directed metastatic work-up is preferred and being
recommended on the basis of cost-effectiveness.
What is the status of practice of staging of cancer in
the Philippines?
It is being practiced by all cancer specialists in one way or another.
It is not commonly communicated to cancer patients and their relatives.
The public is starting to be more aware of cancer staging.
What are recommendations on the practice of staging of cancer in the Philippines?
Despite its limitations, staging of cancer is still useful as a guide to treatment as well as prognostication in the majority of instances where it is utilized. It should not be discarded and there must be efforts on the part of the cancer specialists to continually improve its accuracy.
The public should be informed of what cancer staging is, how it is being done, its usefulness and its limitations.
Symptom-directed rather than routine metastatic work-up is recommended.
For more information:
http://omtumorboard.tripod.com
Email: rjoson2001@yahoo.com