D’Amico Papers
Using Endorectal MRI
June, 2000

We have used the endorectal MRI in settings of significant risk for extra-capsular extension in order to further predict patient outcome. This is based on the landmark studies published by D’Amico, et al.^1,2 Their data evaluated the contribution of the Gleason score and PSA to predict OCD. No attempt was made to incorporate the clinical stage or TRUSP stage as per Partin et al or Narayan et al. Factoring in the percentage of prostate biopsy involvement at the time of diagnosis further enhanced the prediction for OCD. It appears that tumor volume is directly proportional to the number and percentage of positive core biopsies. The greater the tumor volume, the more likely the prostate cancer is not organ confined. D’Amico, et al took this one step further to show that the presence of extra-capsular extension as determined by the endorectal coil MRI significantly affects the rate of 3-year freedom from PSA relapse. A hypothetical example is shown below.

Using the same patient exemplified on page 4 (GS 6, PSA 7.0), the data from D’Amico, et al predict the chances of OCD of 70% if an endorectal MRI were not done. This value is very close to that predicted by Partin, et al (67%). The data from Narayan, et al predict a chance of OCD of 81% for TRUSP B1 and 66% for TRUSP B2. When adding the contribution of the percentages of positive biopsy cores, we get the following information:

The range of predicted OCD results appears consistent with data reported by Narayan, et al in that the likelihood of having OCD is less for TRUSP B2 than TRUSP B1. For our hypothetical patient, he has 3 of 6 positive cores for a B2 lesion (bilateral disease). Given his risk for possible extra-capsular extension (ECE), and endorectal coil MRI was obtained. The results of this scan show a high probability for ECE.

When we apply the endorectal MRI data from D’Amico, et al, we find that the above patient only has a 32% chance of having 3-year freedom from relapse if he were to undergo local treatment. If his endorectal coil MRI had not showed ECE, his chances of having 3-year freedom from relapse would have increased dramatically to 85%.

Tumor volume on final pathology has also been reported to relate to the rate of PSA relapse post-RP. This data by Stamey, et al, also presented at a meeting in Los Angeles in 1996, are summarized in the table below:

References:

1. D’Amico AV, Whittington R, Malkowicz SB, et al: Role of percent positive biopsies and endorectal coil MRI in predicting prognosis in intermediate-risk prostate cancer patients. Cancer J Sci Am 2:343-50, 1996.
    
2. D’Amico AV, Whittington R, Malkowicz SB, et al: A multivariate analysis of clinical and pathological factors that predict for prostate specific antigen failure after radical prostatectomy for prostate cancer. J Urol 154:131-8, 1995.

 

Prostate Cancer Research Institute (PCRI)
 

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