Clinical Investigation
The Influence of Prostate Volume on Outcome After High-Dose-Rate Brachytherapy Alone for Localized Prostate Cancer

https://doi.org/10.1016/j.ijrobp.2013.05.022Get rights and content

Objective

To determine whether late genitourinary toxicity, biochemical control of prostate cancer, and dosimetric parameters in patients with large prostate glands is different from those variables in men with smaller glands after treatment with high-dose-rate brachytherapy alone (HDR-BT).

Methods

From November 2003 to July 2009, 164 patients with locally advanced prostate carcinoma were sequentially enrolled and treated with 34 or 36 Gy in 4 fractions and 31.5 Gy in 3 fractions of 192Ir HDR-BT alone. The median follow-up time was 71 months. Gland size was not considered in the selection criteria for this study. Estimates of freedom from biochemical relapse (FFbR) and late morbidity, stratified by median clinical target volume (CTV), were obtained, and differences were compared.

Results

The median CTV volume was 60 cc (range, 15-208 cc). Dose–volume parameters D90 and V100 (ie, minimum dose to 90% of the prostate volume and volume receiving 100% of the prescribed isodose) achieved in patients with glands ≥60 cc were not significantly different from those with glands <60 cc (P≥.2). Nonetheless, biochemical control in patients with larger CTV was significantly higher (91% vs 78% at 6 years; P=.004). In univariate and multivariate analysis, CTV was a significant predictor for risk of biochemical relapse. This was not at the expense of an increase in either moderate (P=.6) or severe (P=.3) late genitourinary toxicity. The use of hormonal therapy was 17% lower in the large gland group (P=.01).

Conclusions

Prostate gland size does not affect dosimetric parameters in HDR-BT assessed by D90 and V100. In patients with larger glands, a significantly higher biochemical control of disease was observed, with no difference in late toxicity. This improvement cannot be attributed to differences in dosimetry. Gland size should not be considered in the selection of patients for HDR-BT.

Introduction

The use of high-dose-rate brachytherapy (HDR-BT) with remote afterloading sources has an important role in the management of prostate cancer. The dosimetric and radiobiologic advantages of HDR-BT include: (1) no preimplant or perimplant dosimetry because catheters are placed in situ and postimplant dosimetry is undertaken; (2) greater flexibility in volume and dosimetry, which is defined by catheter position and dwell times; and (3) biological dose escalation with large doses per fraction (1).

Traditionally, HDR-BT has been used to give a boost dose of radiation in conjunction with external beam radiation therapy for intermediate-risk to high-risk disease. Now, there are increasing data to suggest that HDR-BT as monotherapy is an effective option, with acceptable low rates of toxicity 2, 3, 4, 5, as a viable treatment choice for a broad spectrum of patients with low-risk to high-risk prostate cancer.

It is widely thought that patients with larger prostate glands are not suitable for brachytherapy. Groupe Européen de Curiethérapie (GEC)/European Society for Radiotherapy and Oncology (ESTRO)--European Association of Urology (EAU) recommendations indicate that patients with a prostate volume of 60 cc and greater may need to be excluded from HDR-BT because of a perceived greater risk of toxicity and pubic arch interference. Cytoreduction with 3 months of androgen deprivation therapy (ADT) has been suggested as a potential strategy to overcome this issue (6). The American Brachytherapy Group suggests that large prostate volume is a relative contraindication and that consideration should be given to either reducing the proximal cover of the median lobe or limited transurethral resection of the prostate before treatment to reduce the risk of urinary symptoms (7).

An earlier report indicated that in a series of 54 patients with limited follow-up times, large prostate volume is not a contraindication to HDR-BT on the basis of dosimetry and toxicity (8). The purpose of this study was to analyze the outcomes in a large cohort of patients receiving HDR-BT monotherapy stratified by gland size.

Section snippets

Patients and procedures

From November 2003 to July 2009, 164 patients with locally advanced prostate carcinoma were sequentially enrolled into an HDR-BT monotherapy trial for prostate cancer. The median follow-up time was 71.3 months. All patients had localized T1 to T3b tumors confirmed by magnetic resonance imaging (MRI), with a prostate-specific antigen (PSA) level < 40 μg/L, normal whole body bone scan, and fitness for general anesthetic. Neoadjuvant hormonal therapy was not routinely used.

Treatment schedule

Thirty patients were

Results

Table 1 summarizes the demographic, disease risk, and treatment characteristics of the 164 patients included in the analysis, divided into 2 groups based on the median CTV (median value for the whole cohort, 60.3 cc; range, 14.7-208.3 cc). A significantly lower number of patients in the large gland group were prescribed ADT (P=.01), but the duration of androgen deprivation was not different. None of the other comparisons were significant.

Table 2 summarizes the dosimetric parameters for small

Discussion

Traditionally, there has been concern regarding the perceived likelihood of significant late genitourinary toxicity developing in patients with large prostate glands (7), although published reports have indicated that this need not be an issue for both low-dose-rate permanent seed implants 14, 15 and HDR-BT (8). The results from this study support the concept that HDR-BT in patients with larger glands does not result in an increased risk of toxicity. All plans in these patients were designed to

References (24)

Cited by (16)

  • GEC-ESTRO ACROP prostate brachytherapy guidelines

    2022, Radiotherapy and Oncology
    Citation Excerpt :

    In addition to ensuring that there are no detectable metastases, good urinary function and predicted life expectancy of >10 years several new concepts have emerged: Gland size: previous guidelines have recommended limits of 50–60 ml however for both LDR and HDR, if there is minimal pubic arch interference, there is now published data showing that much larger glands can be successfully implanted with good results for both dosimetry and biochemical control with no excess toxicity [5,6]. Locally advanced prostate cancer (stage T3): There are now published data showing good oncological outcomes when stage T3a and T3b cancers are treated with either LDR or HDR brachytherapy boost [7,8].

  • Does prostate volume has an impact on biochemical failure in patients with localized prostate cancer treated with HDR boost?

    2016, Radiotherapy and Oncology
    Citation Excerpt :

    In fact, in our cohort, PSA bounces were mainly observed in large prostate volumes and when they were excluded, we observed no detrimental effect of a larger prostate on PSA failure free survival. On the other hand, we did not observe a better PSA failure free survival in the larger gland group as previously reported in the study of Le et al. [10]. In that paper, the authors reported a better PSA outcome in larger glands and concluded that gland size did not affected dosimetry.

  • High dose rate brachytherapy for prostate cancer: Standard of care and future direction

    2016, Cancer/Radiotherapie
    Citation Excerpt :

    Relative contraindications include recent transurethral resection of the prostate and large prostatic volume. Traditionally there was a reluctance to offer high dose rate brachytherapy to such patients but contemporary data suggest that prostate volume should not be a limiting factor in case selection [16,17]. With respect to transurethral resection of the prostate the data is conflicting, with some suggestion of increased genitourinary toxicity, albeit still less than reported with external beam radiotherapy in this setting [18–21].

View all citing articles on Scopus

Conflict of interest: none

View full text