An initial serum PSA level less than 5 ng/ml at diagnosis does not correlate
with tumor volume in low risk prostate cancer patients. Implications for
conservative treatment.
A.Nini, A. Briganti, N. Suardi, A. Gallina, F. Abdollah, D. Di Trapani, G. La Croce, P.
Dell’Oglio, N. Fossati, R. Colombo. G. Guazzoni, P. Rigatti, F. Montorsi.
Introduction & objectives
Active surveillance is a valid management strategy for newly diagnosed low risk
prostate cancer (PCa). In fact a well differentiated, low volume tumor can be
identified based on initial patient characteristic at diagnosis. However, the association
between baseline parameters such as PSA and tumor volume has been poorly
studied in patients with low risk disease. The aim of the study was to assess whether
PSA levels accurately predicts tumor volume in low risk PCa patients who are
candidates for non invasive treatment.
Materials & Methods. We analyzed complete data of 1933 pts treated with radical
prostatectomy (RP) at a single tertiary referral center between 2004 and 2010. Of
these, 714 (36.9%) had pre-operative low risk PCa (cT1, PSA ≤10 ng/ml and biopsy
Gleason score ≤6). Patients were divided into 2 groups: PSA≤5 ng/ml (n=266; 37.3%;
Group 1) and >5ng/ml (n=448; 62.7%; Group 2). All pts had complete data, including
tumor volume at RP. The correlation between PSA at diagnosis and tumor volume
was examined using univariable and multivariable linear regression models, after
accounting for ultrasound measured prostate volume. The same analyses were
repeated separately in each group. Pts and tumor characteristics are reported as
mean ± SD.
Results. PSA at diagnosis was 5.76 ± 1.99 ng/ml, while mean tumor volume was
3.07 ± 2.97 cc (range 0.1-24 cc). Mean tumor volume was 2.42 ± 2.31 cc (range 0.215.5 cc) and 3.46 ± 3.24 cc (range 0.1-24 cc) for patients with PSA≤ 5 ng/ml and
those with PSA >5 ng/ml, respectively (p=0.001). Overall, PSA represented
independent predictors of tumor volume at RP (p<0.001, β 0.237). A positive
association between PSA and tumor volume was confirmed in the sub-group of
patients with PSA between 5 and 10 ng/ml both at univariable and multivariable
analyses (all p<0.001). Conversely, in pts with PSA<5 ng/ml at diagnosis, no
association between baseline PSA and tumor volume was found either at univariable
(p=0.09) or at multivariable analysis (p=0.16). Prostate volume also failed to predict
tumor volume in this patient category (p=0.39).
Conclusion. While higher serum PSA level at the time of diagnosis of low risk PCa
appears to accurately predict larger tumor volumes, this statement does not hold true
for PSA levels below 5 ng/ml. The assumption that patients with low risk disease and
low PSA values at the time of diagnosis have small tumor volumes must thus be
made with caution if the initial PSA drops below this cut-off value. Other variables
beside PSA should be used for the prediction of insignificant prostate cancer in
patients with low PSA values.