Elsevier

Clinical Oncology

Volume 27, Issue 1, January 2015, Pages 16-21
Clinical Oncology

Original Article
Efficacy of High-dose Palliative Radiotherapy for Localised, Castration-resistant Prostate Cancer

https://doi.org/10.1016/j.clon.2014.09.013Get rights and content

Highlights

  • Localised castrate resistant prostate cancer can be associated with significant morbidity.

  • High dose palliative radiotherapy can be a useful palliative manoeuvre to obtain durable local control.

  • High dose palliative radiotherapy to the prostate is associated with minimal significant toxicity.

  • Extended survival is possible in this prostate cancer subgroup.

Abstract

Aims

There are limited outcome data after radiotherapy treatment for clinically localised, castration-resistant prostate cancer. We report our single institution experience on patient outcomes in this group using high-dose palliative radiotherapy (HDPRT).

Materials and methods

A retrospective review of patient hospital records was conducted in prostate cancer patients treated with palliative intent radiotherapy and restricted to those who had castration-resistant disease, no evidence of regional or distant disease and who received a local radiotherapy dose equivalent to 40 Gy or greater.

Results

Fifty-one patients met the study criteria, 88% of these had high-risk disease at initial diagnosis. The median time to delivery of HDPRT was 66 months and the median follow-up from HDPRT was 54 months. Grade 3 or worse toxicity was experienced in 8%. The estimated freedom from local failure, cause-specific survival and overall survival at 5 years were 81, 65 and 35%, respectively. Local procedures were a significant contributor to local morbidity, with the most common procedure a transurethral resection of the prostate (27% patients). Only two patients died from complications of local failure.

Conclusion

HDPRT was well tolerated and provided a high rate of local control in a clinically localised castration-resistant prostate cancer population. Although prostate cancer remained the most frequent cause of death, some patients had extended survival without evidence of disease progression.

Introduction

In men with prostate cancer, the development of castration resistance heralds the emergence of clonogens that have circumvented primary means of androgen deprivation [1]. This phase of the disease is considered end stage in patients with established metastatic disease, with a median survival of about 15 months treated with newer chemotherapy or androgen pathway modulators [1], [2]. A proportion of men, typically those treated with primary androgen deprivation therapy (ADT), develop evidence of castration-resistant prostate cancer (CRPC) without evidence of regional or distant metastatic disease. If no definitive local treatment has previously been delivered, these men represent a management conundrum. The only medical body that currently provides recommendations specifically for asymptomatic or minimally symptomatic non-metastatic CRPC is the American Urological Association. They currently suggest observation with continuation of ADT based on level C evidence [3].

External beam radiotherapy (EBRT) is the obvious modality to control local disease in this highly selected group if symptoms arise, but outcomes of this approach are not well documented. A recent systematic review highlighted the inadequacy of the existing literature in both non-metastatic and metastatic CRPC after pelvic radiotherapy and was unable to make any formal recommendations regarding the optimal dose and fractionation [4].

A high-dose palliative radiotherapy (HDPRT) regimen has been used at our institution for localised CRPC, either when local symptoms become evident or when a patient is considered at imminent risk of their development. The latter is based on clinical evidence of local progression, for example, new palpable tumour progression and/or surrounding tissue invasion. The HDPRT regimens aim to give a total dose of ≥40 Gy with the most common schedule being 50 Gy in 20 daily fractions over 4 weeks. The rationale for HDPRT is that a curative intent dose will probably introduce unnecessary cost, toxicity and time commitment in a group with likely micrometastases and, hence, ultimately, incurable disease, whereas low-dose palliative regimens risk inadequate durability of local control in a cohort that may exhibit extended survival.

The primary aim of this study was to report on clinical local failure in patients who have received HDPRT for localised CRPC. The secondary aims were to report on morbidity inclusive of invasive procedures, tolerability of HDPRT, patterns of disease failure, cause-specific and overall survival. Predictive factors for local failure and overall survival were also explored.

Section snippets

Materials and Methods

Approval for this study was granted from our institutional Human Ethics Committee.

Patient and Treatment Characteristics

In total, 162 patients received a HDPRT regimen in the specified time period. Of these, only 51 patients met the study criteria, with most exclusions being due to the absence of CRPC or the identification of metastases (nodal or distant) before HDPRT. Eighty per cent were deemed node and distant metastasis negative based on imaging within 3 months of radiotherapy, with the remainder based on the absence of suspicion on clinical examination.

Demographic data and disease characteristics for the

Discussion

Localised CRPC is not uncommon when a newly diagnosed patient with N0M0 prostate cancer is treated with ADT alone. In the ADT-only arm of a large randomised trial for newly diagnosed, high-risk prostate cancer, one third of recurrences were identified as local as the first site. The median time to failure from the initiation of primary ADT was 6.8 years [8]. Despite landmark trials showing combined therapy to be more efficacious than ADT alone for high-risk N0M0 disease, primary ADT alone will

Conclusion

HDPRT for N0M0 CRPC showed impressive local control rates with acceptable toxicity. Although extended survival without clinical evidence of disease progression was possible, prostate cancer-specific mortality remained the most frequent cause of death.

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