Extraprostatic extension of prostate cancer
Citation, DOI and article data
Extraprostatic (extracapsular) extension of prostate cancer refers to local tumor growth beyond the fibromuscular pseudocapsule of the prostate gland into the periprostatic soft tissues, in particular, the periprostatic fat and is an established adverse prognostic factor and of importance for prostate cancer staging and therapy.
The prostate gland lacks a true capsule and the so-called "prostate capsule" is a pseudocapsule formed from fibromuscular tissue surrounding three distinct layers of fascia; the anterior, lateral, and posterior fasciae. Anteriorly and apically this pseudocapsule is deficient. Laterally the fascia fuses with the levator fascia. The prostatic venous plexus (Santorini plexus) lies between and passes through, the pseudocapsule and fascia 10-13.
Though imperfect, MRI is superior to transrectal ultrasound, CT, and digital rectal examination in predicting the likelihood of extracapsular extension.
Morphologic predictors of extraprostatic extension at MRI are listed in rough order from most specific to most sensitive 1,3,4:
- seminal vesicle invasion (asymmetric loss of normal high T2 signal in the seminal vesicular lumen)
- neurovascular asymmetry (unequal appearance of neurovascular bundles when an ipsilateral tumor is present)
- frank capsular breach (tumor clearly extends into the periprostatic fat or invades adjacent organs such as rectum or bladder)
- obliteration of the rectoprostatic angle (loss of fatty space between prostate and rectum; posteriorly located tumors only)
- capsular bulge (smooth or irregular convex outward protrusion of prostate margin continuous with the tumor)
- broad capsular contact (≥10-20 mm in a curvilinear length of contact between tumor and capsule) 1,5-7
Treatment and prognosis
On preoperative imaging, the suggestion of extraprostatic extension is important for surgical planning and counseling as resection of the neurovascular bundle may be required.
Extraprostatic extension is associated with a higher risk of recurrence and metastasis and lower cancer-specific survival after radical prostatectomy 1.
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