Evaluation of the prostate bed for local recurrence after radical prostatectomy using endorectal magnetic resonance imaging.
OBJECTIVE
To summarize the results of a 4-year period in which endorectal magnetic resonance imaging (MRI) was considered for all men referred for salvage radiation therapy (RT) at a single academic center; to describe the incidence and location of locally recurrent disease in a contemporary cohort of men with biochemical failure after radical prostatectomy (RP), and to identify prognostic variables associated with MRI findings in order to define which patients may have the highest yield of the study.


METHODS
Between 2007 and 2011, 88 men without clinically palpable disease underwent eMRI for detectable prostate-specific antigen (PSA) after RP. The median interval between RP and eMRI was 32 months (interquartile range, 14-57 months), and the median PSA level was 0.30 ng/mL (interquartile range, 0.19-0.72 ng/mL). Magnetic resonance imaging scans consisting of T2-weighted, diffusion-weighted, and dynamic contrast-enhanced imaging were evaluated for features consistent with local recurrence. The prostate bed was scored from 0-4, whereby 0 was definitely normal, 1 probably normal, 2 indeterminate, 3 probably abnormal, and 4 definitely abnormal. Local recurrence was defined as having a score of 3-4.


RESULTS
Local recurrence was identified in 21 men (24%). Abnormalities were best appreciated on T2-weighted axial images (90%) as focal hypointense lesions. Recurrence locations were perianastomotic (67%) or retrovesical (33%). The only risk factor associated with local recurrence was PSA; recurrence was seen in 37% of men with PSA >0.3 ng/mL vs 13% if PSA ≤0.3 ng/mL (P<.01). The median volume of recurrence was 0.26 cm(3) and was directly associated with PSA (r=0.5, P=.02). The correlation between MRI-based tumor volume and PSA was even stronger in men with positive margins (r=0.8, P<.01).


CONCLUSIONS
Endorectal MRI can define areas of local recurrence after RP in a minority of men without clinical evidence of disease, with yield related to PSA. Further study is necessary to determine whether eMRI can improve patient selection and success of salvage RT.
Department of Radiation Oncology, University of Chicago, Chicago, Illinois 60637, USA. sliauw@radonc.uchicago.edu
Stanley L
SL
Liauw
Sean P
SP
Pitroda
Scott E
SE
Eggener
Walter M
WM
Stadler
Charles A
CA
Pelizzari
Michael W
MW
Vannier
Aytek
A
Oto
D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000175:diagnosis / Q000473:pathology*; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D018579:Patient Selection; D011467:Prostate / Q000473:pathology* / Q000601:surgery; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy / Q000379:methods; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D016879:Salvage Therapy
D017430:Prostate-Specific Antigen