Volumetric modulated arc therapy in prostate cancer patients with metallic hip prostheses in a UK centre

Abstract

Aim

This study aimed to investigate whether IMRT using VMAT is a viable and safe solution in dose escalated RT in these patients.

Background

An increasing number of prostate cancer patients are elderly and have hip prostheses. These implants pose challenges in radiotherapy treatment planning. Although intensity modulated radiotherapy (IMRT) is commonly used, there is a lack of clinical studies documenting its efficacy and toxicities in this subgroup of patients.

Materials and methods

The data from 23 patients with hip prostheses and non-metastatic prostate cancer treated with VMAT (volumetric modulated arc therapy) between 2009 and 2011, were retrospectively analyzed. Baseline characteristics, treatment details and outcome data were collected on all patients. The median follow up was 40.9 months. MRI-CT image fusion was performed and the treatment plans were created using RapidArc™ (RA) techniques utilizing 1 or 2 arcs and 10[[ce:hsp sp="0.25"/]]MV photon beams.

Results

96% of patients were treated with a dose of 72[[ce:hsp sp="0.25"/]]Gy/32 fractions over 44 days. 21/23 plans met the PTV targets. The mean homogeneity index was 1.07. 20/23 plans met all OAR constraints (rectum, bladder). Two plans deviated from rectal constraints, four from bladder constraints; all were classed as minor deviations. One patient experienced late grade 3 genitourinary toxicity. Three other patients experienced late grade 2 or lower gastrointestinal toxicity. One patient had biochemical failure and one had a non-prostate cancer related death.

Conclusions

VMAT provides an elegant solution to deliver dose escalated RT in patients with unilateral and bilateral hip replacements with minimal acute and late toxicities.