Deficiencies in AJCC Staging System for Prostate Cancer

Abstract & Commentary

By William B. Ershler, MD, Editor, INOVA Fairfax Hospital Cancer Center, Fairfax, VA; Director, Institute for Advanced Studies in Aging, Washington, DC.

Synopsis: AJCC staging for prostate cancer does not discriminate between regional node and distant metastases. In a review of more than 4000 patients treated at M.D. Anderson for 2 decades, survival data would indicate that such distinction would be of value.

Source: Taylor SH, et al. Inadequacies of the current American Joint Committee on Cancer staging system for prostate cancer. Cancer. 2006;106:559-565.

The world health organization first introduced the concept of staging for cancer in 1929 in an attempt to create a standardized format for comparative purposes in assessing treatment outcomes from different locales.1 Since then, the importance of accurate staging has become widely recognized. For clinicians, assessment of tumor stage prior to initial treatment is of great value in selection of the approach to be undertaken. For clinical investigators, accurate staging allows more reliable comparisons when assessing one treatment vs another.

Typically, for solid tumors, established staging systems have evolved to incorporate the extent of disease locally and to determine whether regional or distant metastases are apparent. Although quite reliable for most tumors, Taylor and colleagues have called to question the current widely used system for prostate cancer. Most clinicians treating prostate cancer rely on the American Joint Committee on Cancer (AJCC) staging which curiously does not distinguish between regional node involvement and distant metastases—patients with either are considered Stage IV.

To examine this argument, a retrospective review of 2 decades' experience of prostate cancer patients evaluated and treated at Taylor et al's institution was undertaken. Staging by the AJCC criteria was compared to the more expansive system recommended by the Surveillance, Epidemiology, and End Results (SEER) program (National Cancer Institute). The SEER staging system employed typically by tumor registries and for epidemiological studies (but not generally by practicing urologists and medical oncologists) describes the extent of spread from the point of origin with specific notation for site of metastases (ie, which node groups and which organs).

During the years 1982 through 2001 there were 4141 patients staged and treated. Descriptive analyses of demographic and disease variables were undertaken and survival and Cox proportional hazards regression analyses were performed.

Using the AJCC system the median survival for patients with Stage IV disease (which includes those with regional nodes only as well as those with distant metastases) was 86 months. However, the median survival for those with regional (but not distant) metastases was 134 months compared to 42 months for those who had distant metastases. When compared to patients with localized disease, patients with positive regional lymph nodes were 2.5 times more likely to die whereas those with distant metastases, the mortality risk was 10.1 times greater.

Thus, this analysis demonstrated a substantial difference in prognosis between those with regional lymph node spread compared to those with distant metastasis and the authors propose that the current AJCC classification be considered for modification.

Commentary

Medical oncologists understand and appreciate the value of staging and use it to some degree in the formulation of treatment plans on practically every cancer patient under their care. The current report highlights a seeming error in the current system and likely the AJCC will review and consider revision. However, although the current system does not distinguish Stage IV (regional nodes) from Stage IV (distant metastases), it is interesting to note that in the current series those with regional disease were treated differently (more surgery and radiation) and those with distant disease, more systemic (hormonal) treatment. Thus, the current AJCC system does not serve one of its intended purposes: to guide therapy. The concept of staging is embedded in the oncologist's brain and despite the system, the mindset remains local/regional/distant, and this information, coupled with PSA level and rate of rise, Gleason score and histological features form the root of the treatment plan.

Reference

1. Fleming ID, et al. AJCC Cancer Staging Manual. 5th ed. Philadelphia, PA: Lippincott-Raven. 1998.