PROSTATE-CANCER STAGING - CORRELATION BETWEEN ULTRASOUND DETERMINED TUMOR CONTACT LENGTH AND PATHOLOGICALLY CONFIRMED EXTRAPROSTATIC EXTENSION

Purpose: We determine whether a new parameter, the amount of tumor in contact with the fibromuscular rim (capsule) of the prostate, correlat es with extraprostatic extension, and ascertain whether estimating the new parameter using transrectal ultrasonography can predict extrapros tatic extension. Materials and Methods: We analyzed step sectioned pro statectomy specimens from 189 patients who had had positive peripheral zone biopsies. We measured the contact length, maximum length (mm.) o f the portion of the peripheral zone cancer that was in contact with t he fibromuscular rim, and determined the contact ratio from the quotie nt (%) of the contact length divided by the tumor circumference. We ev aluated the correlation between the pathological and ultrasound measur ements of these parameters, as well as the accuracy of these criteria for predicting microscopic extraprostatic extension. Results: Among th e 189 cancers there was a significant difference (p <0.0001) between o rgan confined tumors and tumors with extraprostatic extension in conta ct length and contact ratio. There was a positive correlation (r = 0.6 91) between the contact lengths measured ultrasonically and histologic ally among 95 patients who had hypoechoic lesions associated with posi tive biopsies. A receiver operating characteristics curve of the abili ty of ultrasound estimated contact length to predict extraprostatic ex tension revealed the best cutoff value to be 23 mm. with 77% accuracy. Logistic regression analysis revealed that pathological contact lengt h correlated better with extraprostatic extension than tumor volume, G leason score, prostate specific antigen (PSA) level and pathological c ontact ratio. The best preoperative predictor of extraprostatic extens ion was the ultrasound contact length, followed by the contact ratio, PSA value, percentage of the biopsy specimen that was cancer and prese nce of perineural invasion in the biopsy specimen. Multiple logistic r egression analysis revealed that the predictability of ultrasound cont act length was improved by considering PSA value also. Probability plo ts for predicting extraprostatic extension were developed by combinati on of ultrasound contact length with PSA value. Conclusions: The lengt h of tumor contact with the fibromuscular rim is more significantly re lated to extraprostatic extension than tumor volume, PSA level and tum or grade. For hypoechoic cancers a new ultrasound staging criterion, c ontact length, has been defined. For men who are clinically candidates for radical prostatectomy and have peripheral zone hypoechoic cancers the combination of ultrasound contact length and PSA value is the bes t predictor of extraprostatic extension.