Stage Information
TNM Definitions
AJCC Stage Groupings
Jewett Staging System
Detection of asymptomatic metastatic disease in prostate cancer is greatly
affected by the staging tests performed. Radionuclide bone scans are currently
the most widely used tests for metastases to the bone, which is the most common site of
distant tumor spread. Magnetic resonance imaging (MRI) is more sensitive than
radionuclide bone scans but is impractical for evaluating the entire skeletal
system. Some evidence suggests that serum prostate-specific antigen (PSA)
levels can predict the results of radionuclide bone scan in newly
diagnosed patients. In one series, only 2 of 852 patients (0.23%) with a PSA of less than 20 µg/L had a positive bone scan in the absence of
bone pain.[1] In another series of 265 prostate cancer patients, 0 of 23 patients with a
PSA of less than 4 μg/L had a positive bone scan, and 2 of 114 patients with a PSA of less than 10 μg/L had
a positive bone scan.[2] Prognosis is worse in patients with pelvic lymph node
involvement.
Whether to subject all patients to a pelvic lymph node dissection
(PLND) is debatable, but in patients undergoing a radical retropubic
prostatectomy, the nodal status is ascertained as a matter of course. In patients who are undergoing a radical perineal prostatectomy in whom the PSA
value is less than 20 and the Gleason sum is low, however, evidence is mounting that a
PLND is probably unnecessary, especially in patients whose malignancy was not
palpable but detected on ultrasound.[3,4] A PLND remains the most accurate
method to assess metastases to pelvic nodes, and laparoscopic PLND has been
shown to accurately assess pelvic nodes as effectively as an open procedure.[5]
The exact role of PLND in diagnosis and subsequent treatment is being evaluated,
though it has already been determined that the length of hospital stay
following laparoscopic PLND is shorter than that following an open procedure.
The determining factor when deciding if any type of PLND is indicated is
whether definitive therapy may be altered. Likewise, preoperative seminal
vesicle biopsy may be useful in patients with palpable nodules who are being
considered for radical prostatectomy (unless they have a low Gleason score)
because seminal vesicle involvement could affect choice of primary therapy and
predicts for pelvic lymph node metastasis.[6]
In patients with clinically localized (stage I or stage II) prostate cancer, Gleason
pathologic grade and enzymatic serum prostatic acid phosphatase values (even
within normal range) predict the likelihood of capsular penetration, seminal
vesicle invasion, or regional lymph node involvement.[3] Analysis of a series
of 166 patients with clinical stage I and stage II prostate cancer undergoing radical
prostatectomy revealed an association between Gleason biopsy score and the risk
of lymph node metastasis found at surgery. The risks of node metastasis for
patients grouped according to their Gleason biopsy score was 2%, 13%, and 23%
for Gleason scores of 5, 6, and 8, respectively.[7]
Transrectal ultrasound (TRUS) may facilitate diagnosis by directing needle
biopsy; however, ultrasound is operator dependent and does not assess lymph
node size. Moreover, a prospective multi-institutional study of preoperative
TRUS in men with clinically localized prostate cancer felt to be eligible for
radical prostatectomy showed that TRUS was no better than digital rectal
examination in predicting extracapsular tumor extension or seminal vesicle
involvement.[8] Computed tomography (CT) can detect grossly enlarged nodes but
poorly defines intraprostatic features;[9] therefore, it is not reliable for
the staging of pelvic node disease when compared to surgical staging.[10] Although MRI has been used to detect extracapsular extension of prostate cancer, a
positive-predictive value of about 70% and considerable interobserver variation
are problems that make its routine use in staging uncertain.[11] Ultrasound and MRI, however, can reduce clinical understaging and thereby improve patient
selection for local therapy. Preliminary data with the endorectal MRI coil for
prostate imaging report the highest sensitivity and specificity for
identification of organ-confined and extracapsular disease.[3,12,13] MRI is a
poor tool for evaluating nodal disease.
Two systems are in common use for the staging of prostate cancer. The Jewett
system (stages A through D) was described in 1975 and has since been
modified.[14] In 1997, the American Joint Committee on Cancer (AJCC) and the
International Union Against Cancer adopted a revised tumor, nodes, metastasis (TNM) system that employs
the same broad T stage categories as the Jewett system but includes
subcategories of T stage, such as a stage to describe patients diagnosed
through PSA screening. This revised TNM system is clinically useful and more
precisely stratifies newly diagnosed patients. In 2002, the AJCC further revised the TNM classification system.[15] Both staging systems are
shown below, and both are used in this summary to discuss treatment
options. A thorough review of the controversies of staging in prostate cancer
has been published.[16]
TNM Definitions
Primary tumor (T)
- TX: Primary tumor cannot be assessed
- T0: No evidence of primary tumor
- T1: Clinically inapparent tumor not palpable nor visible by imaging
- T1a: Tumor incidental histologic finding in 5% or less of tissue
resected
- T1b: Tumor incidental histologic finding in more than 5% of tissue
resected
- T1c: Tumor identified by needle biopsy (e.g., because of elevated PSA)
- T2: Tumor confined within prostate*
- T2a: Tumor involves 50% or less of one lobe
- T2b: Tumor involves more than 50% of one lobe but not both lobes
- T2c: Tumor involves both lobes
- T3: Tumor extends through the prostate capsule**
- T3a: Extracapsular extension (unilateral or bilateral)
- T3b: Tumor invades seminal vesicle(s)
- T4: Tumor is fixed or invades adjacent structures other than seminal
vesicles: bladder neck, external sphincter, rectum, levator muscles, and/or pelvic wall
* [Note: Tumor that is found in one or both lobes by needle biopsy but is not palpable or
reliably visible by imaging is classified as T1c.]
** [Note: Invasion into the prostatic apex or into (but not beyond) the
prostatic capsule is classified as T2 not T3.]
Regional lymph nodes (N)
- Regional lymph nodes are the nodes of the true pelvis, which essentially are
the pelvic nodes below the bifurcation of the common iliac arteries. They
include the following groups (laterality does not affect the N
classification): pelvic (not otherwise specified [NOS]), hypogastric, obturator, iliac (i.e., internal,
external, or NOS), and sacral (lateral, presacral, promontory
[e.g., Gerota], or NOS). Distant lymph nodes are outside the confines of the
true pelvis. They can
be imaged using ultrasound, CT, MRI,
or lymphangiography and include: aortic (para-aortic, periaortic, or lumbar),
common iliac, inguinal (deep), superficial inguinal (femoral), supraclavicular,
cervical, scalene, and retroperitoneal (NOS) nodes.
Although enlarged lymph nodes can occasionally be visualized, because of a stage migration associated with PSA screening, very few patients will be found to have nodal disease, so false-positive and false-negative results are common when imaging tests are employed. In lieu of imaging, risk tables are generally used to determine individual patient risk of nodal involvement. Involvement of distant lymph nodes is classified as M1a.
- NX: Regional lymph nodes were not assessed
- N0: No regional lymph node metastasis
- N1: Metastasis in regional lymph node(s)
Distant metastasis (M)*
- MX: Distant metastasis cannot be assessed
(not evaluated by any modality)
- M0: No distant metastasis
- M1: Distant metastasis
- M1a: Nonregional lymph node(s)
- M1b: Bone(s)
- M1c: Other site(s)
with or without bone disease
* [Note: When more than one site of metastasis is present, the most advanced
category (pM1c) is used.]
Histopathologic grade (G)
- GX: Grade cannot be assessed
- G1: Well differentiated (slight anaplasia)
(Gleason score of 2–4)
- G2: Moderately differentiated (moderate anaplasia)
(Gleason score of 5–6)
- G3-4: Poorly differentiated or undifferentiated (marked anaplasia)
(Gleason score of 7–10)
AJCC Stage Groupings
Stage I
Stage II
- T1a, N0, M0, G2–4
- T1b, N0, M0, any G
- T1c, N0, M0, any G
- T1, N0, M0, any G
- T2, N0, M0, any G
Stage III
Stage IV
- T4, N0, M0, any G
- Any T, N1, M0, any G
- Any T, any N, M1, any G
Jewett Staging System
Stage A
Stage A is clinically undetectable tumor confined to the prostate gland and is
an incidental finding at prostatic surgery.
- Substage A1: well differentiated with focal involvement and usually left
untreated
- Substage A2: moderately or poorly differentiated or involves multiple foci in the gland
Stage B
Stage B is tumor confined to the prostate gland.
- Substage B0: nonpalpable and PSA detected [17]
- Substage B1: single nodule in one lobe of the prostate
- Substage B2: more extensive involvement of one lobe or involvement of both
lobes
Stage C
Stage C is tumor clinically localized to the periprostatic area but extending
through the prostatic capsule; seminal vesicles may be involved.
- Substage C1: clinical extracapsular extension
- Substage C2: extracapsular tumor producing bladder outlet or ureteral
obstruction
Stage D
Stage D is metastatic disease.
- Substage D0: clinically localized disease (prostate only) but persistently
elevated enzymatic serum acid phosphatase titers
- Substage D1: regional lymph nodes only
- Substage D2: distant lymph nodes and metastases to bone or visceral organs
- Substage D3: D2 prostate cancer patients who relapsed after adequate endocrine therapy
References
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