Aims: To evaluate the prognostic significance of magnetic resonance imaging (MRI) tumour stage in clinically localised prostate cancer.
Materials and methods: Between 1988 and 1999, 199 men with clinically localised prostate cancer (T -T4, N0/Nx, M0) were treated with neo-adjuvant androgen deprivation and radical radiotherapy, and were staged using MRI. Concordance between clinical tumour (cT) stage, as determined by digital rectal examination, and MRI tumour (mT) stage was assessed. Univariate and multivariate analyses using the Cox proportional hazards model were used to study the prognostic role of cT stage and mT stage in addition to established prognostic factors.
Results: Of these 199 patients, 103 (52%) were upstaged on MRI, seven (3%) were downstaged, and in 89 (45%) cT and mT stages were concordant. With median follow-up of 3.8 years, 5-year freedom from prostate-specific antigen (PSA) failure was 48% (95% confidence interval (CI) 39-56%). On univariate analysis, freedom from PSA failure was associated with mT stage (P = 0.009) as well as Gleason score (P < 0.001) and initial PSA (P < 0.001), but not cT stage (P = 0.449). On multivariate analysis, Gleason score (P = 0.001), initial PSA (P < 0.001), but not mT stage (P = 0.112) remained independent determinants of freedom from PSA failure. For the subgroup of 149 patients with cT1-2 disease, mT stage was a significant predictor of increased risk of PSA failure on univariate analysis (P = 0.005), but not multivariate analysis (P = 0.19).
Conclusion: Freedom from PSA failure was more closely associated with mT stage than cT stage. Future studies are warranted to determine whether mT stage is an independent determinant of treatment outcome.