Stage Information for Prostate Cancer
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. Computed tomography (CT) can detect grossly enlarged nodes but poorly defines intraprostatic features; therefore, it is not reliable for the staging of pelvic node disease when compared to surgical staging. 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. 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. 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. The AJCC further revised the TNM classification system in 2002 and, most recently, in 2010. 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.
Definitions of TNM
The AJCC has designated staging by TNM classification to define prostate cancer.
Table 1. Primary Tumor (T)a
a Reprinted with permission from AJCC: Prostate. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 457-68.
b Tumor found in one or both lobes by needle biopsy, but not palpable or reliably visible by imaging, is classified as T1c.
c Invasion into the prostatic apex or into (but not beyond) the prostatic capsule is classified not as T3 but as T2.
|TX||Primary tumor cannot be assessed.|
|T0||No evidence of primary tumor.|
|T1||Clinically inapparent tumor neither palpable nor visible by imaging.|
|T1a||Tumor incidental histologic finding in ?5% of tissue resected.|
|T1b||Tumor incidental histologic finding in >5% of tissue resected.|
|T1c||Tumor identified by needle biopsy (e.g., because of elevated PSA).|
|T2||Tumor confined within prostate.b|
|T2a||Tumor involves ?one-half of one lobe.|
|T2b||Tumor involves >one-half of one lobe but not both lobes.|
|T2c||Tumor involves both lobes.|
|T3||Tumor extends through the prostate capsule.c|
|T3a||Extracapsular extension (unilateral or bilateral).|
|T3b||Tumor invades seminal vesicle(s).|
|T4||Tumor is fixed or invades adjacent structures other than seminal vesicles such as external sphincter, rectum, bladder, levator muscles, and/or pelvic wall.|