The Clinical Stage: Its Definition and Importance in Prostate Cancer

By Harry Pinchot (PCRI Helpline Staff Member)
and Stephen B. Strum, MD
Reprinted from PCRI Insights April 2000 v3.1

Clinical staging (CS) is extremely important in the evaluation and management of the prostate cancer (PC) patient. The CS is an expression of both tumor volume and the extent of disease (EOD). It is, therefore, part of the picture that determines how the patient can best be treated. Input from the CS helps determine whether or not the patient is an excellent candidate for radical prostatectomy (RP), external beam radiation therapy (EBRT), seed implantation (SI), or cryosurgery. Whether to use ADT (androgen deprivation therapy), and/or how long to use it, is also determined, in part, by the CS prior to treatment.

The CS that we use is part of the TNM staging system. In the TNM acronym, T stands for tumor and relates to the primary tumor in the prostate: N relates to PC spread to lymph nodes; and M indicates metastatic disease, most commonly in the bone but also potentially in the liver, lung, or other non-lymph node sites.

CS is called “clinical stage” since it does not involve the findings of pathologic examination, which is usually the result of microscopic evaluation.*

* This is not exactly true as seen with the CS T1a, T1b, and T1c based on the percent involvement by prostate cancer of the chips examined microscopically after a TURP.

Instead, CS involves non-invasive studies such as DRE (digital rectal exam) and TRUSP (transrectal ultrasound of the prostate). It may also involve endorectal MRI with or without spectroscopy, ProstaScint scanning, bone scanning, CT, or even the use of the PET scan.

Again, most of the time, the CS equates with the T stage as a reflection of the findings of the DRE.

This is because with PSA testing, most men initially present with far less disease than they did 10 to 15 years ago. The frequency of advanced PC at diagnosis has dramatically fallen. Therefore, most of our treatment evaluation at diagnosis fails to show evidence of distant disease.

Sometimes, physicians at centers that are focused on TRUSP, endorectal MRI or ProstaScint will include, and properly so, their modality as part of the clinical stage. Since the vast majority of urologists doing ultrasound use this procedure solely for guiding the biopsy needle and not for clinical staging, this often confuses both the patient and the physician. Since there are so few patients having endorectal MRI scanning at this time and so few doctors incorporating ProstaScint scanning into the clinical staging schema, it is probably wise to restrict the CS to the findings of DRE. When the other studies are used, one could indicate the “enhanced” CS. For example:

CS T2a (T2c-endorectal MRI) would indicate a DRE CS of T2a that is upgraded to T2c using the endorectal MRI.

Bone scanning and CT scanning are seldom abnormal at the time of diagnosis unless the PSA is > 20.

Patients with PSA levels of less than or equal to 10 are told not to bother with CT or bone scans since their yield is negligible i.e. 1 in 200. This is especially true for men having a validated Gleason score of less than 7 and especially if the Gleason score does not contain any Gleason grade 4 or 5. Therefore, GS of [2,2], [2,3], [3,2], [3,3] and [3,4] in the setting of a baseline PSA of 10 or less does not require either bone scanning or CT scanning as part of the staging process.

Following this advice alone would save over $200 million a year in wasteful expenditures and spare patients from unnecessary radiation as well as free up healthcare personnel.

The CS is logically divided into 4 major categories: T1, T2, T3 and T4 stages.

T1 is non-palpable PC. It is subdivided into T1a, T1b and T1c. The most common CS is T1c: prostate cancer diagnosed because of an abnormal PSA in the setting of no palpable abnormality(ies) on DRE. T1a and T1b are also not associated with any palpable disease. T1a is PC found incidentally at the time of a TURP (transurethral resection of the prostate) and involves <= 5% of the tissue pieces or chips. T1b PC involves more than 5% of the chips.

Figure 1 represents a prostate gland with no palpable PC and illustrates a CS of T1c.

When reporting any CS, it is important that physicians take the time to do the exam carefully. Ample lubricant should be used and the finger inserted slowly into the rectum, giving the external rectal sphincter a chance to adjust to the pressure of the finger. The physician should estimate the size of the gland and also mentally note any areas of concern. There should be no lesions that are suspicious for PC if a patient is given a T1c CS. The physician should record his findings in the medical chart objectively, without first looking at prior examinations or other studies that might bias him.

T2 CS involves a palpable tumor apparently confined within the prostate.

T2a reveals a palpable tumor involving 50% or less of 1 lobe of the prostate.

T2b involves palpable PC involving more than 50% of 1 lobe. T2c involves palpable disease involving both lobes. These stages are shown in Figures 2-4 below.

Patients with a CS of T2 disease have a greater tumor volume since the palpability of disease denotes greater amounts of PC. However, since only the posterior aspect of the prostate is palpable with a digital examination, it is possible that a patient could have a larger PC tumor and still have T1c disease rather than T2a-c disease. In Dr. Strum's clinical experience, however, this is not often the case.

Patients having T2 disease are still candidates for any local therapy. If RT is being considered, it is reasonable to treat the cancer with ADT to reduce the tumor volume and thereby increase the likelihood of a more complete cell kill with RT.

In addition, reduction of the prostate gland volume itself can help decrease radiation scatter to the adjacent bladder and rectum and eliminate the problem of pubic arch interference with RT. Our goal is to reduce the gland volume to below 40 cubic centimeters (or grams), and we often continue ADT until the gland size is as small as 10-15 cubic centimeters (or grams).

Figure 2 is an example of a gland with a clinical stage of T2a. The red area denotes a palpable lesion consistent with malignancy.

Figure 3 is an example of a gland with clinical stage T2b where >50% of one lobe is involved.

Figure 4 is an example of a gland with clinical stage T2c where both lobes are involved (bilateral disease).

Patients with bulkier disease as seen with CS T2b-c are certainly candidates for ADT to reduce tumor burden. These patients might be more optimally treated with ADT until all palpable abnormality has been resolved and perhaps for 2-3 months after non-palpability is achieved.

Patients with higher CS levels of disease have a lower chance of a long-term cure with RP based on the studies by Pound et al.1 The “Prostate Assistant” software on our Web site (www.prostate-cancer.org) clearly demonstrates the contribution of the CS as part of the risk assessment obtained using the Partin Tables. All patients and physicians should utilize this and other combined modality staging tools to assess the patient.

When the DRE detects palpable disease sufficient to indicate that the tumor has penetrated through the prostate capsule, the CS is called T3 disease. This is also subdivided into categories.

T3a indicates that the tumor is extending through the capsule on one side (unilateral involvement) as shown in Figure 5.

T3b indicates that the tumor is extending through the capsule on both sides (bilateral involvement) as shown in Figure 6.

A T3c clinical stage indicates that tumor is palpable and appears to involve the seminal vesicle(s). Figure 7 shows what might be palpable on DRE and thereby indicate a T3c CS.

T3 disease is not likely to be cured with RP. Such patients are best treated with prolonged ADT and with RT consolidation to the prostate and regional tissues.

Patients with a CS of T3 disease are not good candidates for seed implantation as sole therapy (monotherapy). Tumor reduction (cytoreduction) with ADT should be the first treatment and be followed by consolidation with some form of local therapy such as EBRT. It is possible to consider brachytherapy (seed implants) combined with EBRT with the idea that the brachytherapy is a boost to areas of greatest tumor bulk. Bolla et al reports good results treating patients with T3 (and T4) disease with prolonged ADT (lasting three years) combined with external beam RT. This study compared patients who received EBRT alone with those who received EBRT with ADT continued for a total of three years2. (See Table 1.)

It would seem more reasonable to have first treated the patients with ADT to achieve tumor volume reduction before initiating EBRT since the effectiveness of radiation therapy is so dependent on tumor volume.

A T4 Clinical Stage is not commonly seen at the original diagnosis. It indicates local invasion of a structure adjacent to the prostate other than the seminal vesicle(s).

T4a indicates a DRE exam with tumor invading the bladder neck, external sphincter or rectum. Figure 8 indicates a CS of T4a.

T4b indicates clinical findings of invasion into the levator ani muscles or a tumor that is fixed to the pelvis. Figure 9 is an example of T4b disease.

Conclusions

The clinical stage or CS is used in the Partin Tables for overall risk assessment, and in the Bluestein algorithm for determining risk of lymph node involvement.

• It is the least expensive tool we have for our evaluation of men with prostate cancer.
  
• If done accurately, the CS provides meaningful information that correlates significantly with the findings of TRUSP and/or endorectal MRI.
  
• The CS yields immediate feedback as to the status of tumor volume reduction resulting from ADT.
  
• The CS reflects the state of response to any form of local therapy and must be part of the surveillance of the man with PC. This assessment tool becomes even more important in men with high Gleason score PC (8-10) where tumor cells often secrete little PSA, thus making the PSA a much less reliable tool to determine remission or recurrence.

Remember, a good medical Columbo uses all the clues available to him. Physicians must learn to use this tool for its many applications and perform a DRE without traumatizing the patient.

References

1. Pound CR, Partin AW, Epstein JI, et al: Prostate-specific antigen after anatomic radical retropubic prostatectomy. Patterns of recurrence and cancer control. Urol Clin North Am 24:395-406, 1997.

2. Bolla M, Gonzalez D, Warde P, et al: Improved survival in patients with locally advanced prostate cancer treated with radiotherapy and goserelin. N Engl J Med 337:295-300, 1997.

 

Prostate Cancer Research Institute (PCRI)

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