Factors predicting for urinary morbidity following 125iodine transperineal prostate brachytherapy

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Abstract

Purpose

To assess factors related to the risk of acute urinary retention and other morbidity indices in patients undergoing transperineal seed implantation of the prostate.

Materials and methods

One hundred and seventy-three consecutive patients treated with 125Iodine transperineal interstitial permanent prostate brachytherapy (TIPPB) were evaluated. Various demographic, pathological, symptomatic, urodynamic and dosimetric values were assessed in relation to the incidence of acute urinary retention as well as the International Prostate Symptom Score (IPSS) dynamics. Patients were routinely placed on α-blockade postimplant. Dosimetry was based on CT scan one month postimplant.

Results

Acute urinary retention developed in thirty-four patients (19.7%), at a median time of four days. Peak urinary flow rate was the only independent factor which varied significantly between those suffering retention and those not (median of 16 and 19.5 ml/s respectively, P=0.005). Median preimplant IPSS was 4.0, with a median peak of 16 at 3 months. Actuarial median time to return to baseline IPSS was at 15 months. The peak IPSS above preimplant levels was correlated significantly in multivariate analysis with the number of seeds implanted superior to the physician-nominated anatomical base level of the prostate (P<0.009), as well as lower preimplant IPSS values.

Conclusions

In our series, preimplant urinary flow rate was the most important factor predictive of postimplant acute urinary retention. The patients' risk of having heightened IPSS change following implantation was correlated to a lower preimplant IPSS and an increased number of seeds implanted above the level of the prostatic base, possibly reflecting bladder base rather than urethral irritation in the development of acute urinary morbidity.

Introduction

Transperineal interstitial permanent prostate brachytherapy (TIPPB) has become a commonly performed procedure for definitive early prostate cancer treatment in North America [21]. This procedure has been taken up in Australia as an alternative to radical prostatectomy in some patients [18]. A number of series with mature follow-up show disease control rates which appear comparable to that achieved with radical prostatectomy in similar patient groups [5], [23].

With equivalent control rates, the choice of treatment depends on the relative morbidities of the various procedures. Lower urinary tract symptoms (LUTS) are a prominent category of morbidity in men undergoing TIPPB [32]. The symptoms include irritative symptoms in the period after implantation, obstructive symptoms sometimes requiring catheterisation, and in the longer term, incontinence [22].

From the onset of a TIPPB program for men with early localised prostate cancer we prospectively collected data on LUTS using a validated and widely employed survey instrument [2], as well as objectively measured urinary flow rates on men prior to implant. We reviewed the incidence, severity and time course of LUTS in men after TIPPB to determine if these morbidities might be predicted by pretreatment or treatment related factors.

Section snippets

Materials and methods

Men with cT1b-T2b, N0, M0 adenocarcinoma prostate (according to AJCC 1997 criteria [6]) with presenting PSA≤10 ng/ml and Gleason score (GS) histopathological pattern of ≤6 were considered for our seed TIPPB program. For this analysis, a cohort of men implanted between December 1998 and December 2003 who had no additional external-beam radiotherapy were chosen. Following routine clinical evaluation, patients filled out self assessment International Prostate Symptom Score (IPSS) questionnaires [2]

Results

One hundred and seventy-three men implanted with TIPPB were eligible for analysis, with a median age of 61 years (range 45–77 years). Median preimplant PSA was 5.8 ng/ml, with 92% having PSA≤10 ng/ml; a further twelve patients had levels between 10.1 and 13.5 ng/ml. One patient had a Gleason score of seven, all others being GS≤6. The clinical staging was T1c in 72 patients, T2a in 67, T2b in 19 and T2c in 15. Four patients had undergone previous transurethral resection of prostate (TURP) for

Acute urinary retention

Acute urinary retention is a morbidity which can affect patient quality of life following TIPPB. Many investigators have attempted to delineate factors which predispose to urinary retention postimplant. Overall reported incidence rates vary between 5 and 35% [3], [4], [9], [10], [14], [17], [20], [25], [26], [27], [29], [30], [32], with the present series showing an 19.7% rate of catheter reinsertion.

Larger prostate volume has been the most uniformly described preimplant risk factor for

Conclusions

AUR is a relatively common complication following prostate TIPPB, occurring mostly within the first two weeks following implantation. This result is consistent with many other published trials. Also similar is the temporal distribution of urinary symptoms assessed by the IPSS. Peak urinary flow rate appears to be a strong predictor for AUR, and is more reliable than IPSS in this regard. The peak in the IPSS response to TIPPB is inversely correlated to the preimplant IPSS, and positively

Acknowledgements

The authors wish to thank Mrs Karen Scott and Dr Janet Havercroft for their contribution in maintenance of the clinical and physics databases respectively.

References (32)

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