Intra-operative Radiotherapy

Intraoperative radiotherapy versus external beam radiotherapy in breast conserving surgery   Jan 2014

Conventional radiotherapy after breast conserving surgery consists of 50Gy administered as 25 divided doses (5 days per week for 5 weeks). This treatment is usually commenced about 6 weeks after surgery to allow time for the wounds to heal. This regime requires the patient to stay in the vicinity of the treatment centre for 5 weeks.  For people living out of town this can create problems with accommodation and time away from work and family.

There has been considerable interest in methods that can reduce the treatment time.

Accelerated partial breast irradiation or short course radiotherapy aims to deliver the total dose of radiation in a shorter time either by reducing the total dose or increasing each fraction. These methods can reduce treatment to about three weeks but are only suitable for selected small "well behaved cancers"

A second approach is to plan to deliver the radiotherapy intra-operatively.

2 studies have looked at this option.

ELIOT is a study performed at the European Institute of Oncology in Milan. It used a linear accelerator to provide the electron beam. A single 21Gy dose was given intra-operatively. A special lead shielded theatre was required. The chest was protected with a metal disc placed in the depths of the surgical wound. 1305 patients were included in the study and follow-up is presently 5.8 years. The local recurrence rate in the intraoperative treatment group is 4%  higher at 5 years and estimated to double by  10 years. There was no difference in death rates between the 2 groups. This difference in local recurrence is however quite significant. The method is also limited by the requirements for a specially modified theatre and expensive radiotherapy device.

The TARGIT study was organised by researchers from University College London and recruited patients from 33 centres across Europe. Over 1200 women now have follow up of 5 years. The study compared a single intraoperative dose of radiation delivered with the Intra-beam device to conventional external beam irradiation. The Intra-beam device does not require a specialised operating theatre but patients would need to travel to a site offering this option. (currently there is only one Intra-beam in New Zealand located on the North Shore Auckland. The initial TARGIT study looked at 2 different groups of patients. The first had their radiotherapy at the time of initial cancer surgery. The selection criteria for this method were quite strict and included the need for small tumours with clear margins and consequently some patiernts were found to have unsuitable pathology and then required conventional external beam radiation (on top of the intraoperative dose) This group had high rates of fibrosis affecting the treated breast. The second group had their radiotherapy as a second procedure once the surgical histology was known This of course means a second procedure in theatre. (some concern exists about technical issues such as accurately identifying the tumour bed in this situation) The local recurrence rate in those treated with  Intrabeam are slightly higher than with conventional external beam treatment. Interestingly the incidence of cardiac events in the Intra-beam group was significantly lower raising the question of cardiac safety with standard external beam therapy.

These new methods do raise exciting possibilities for streamlining and simplifying radiation treatment. There are however still many technical issues that need to be resolved and clarified before these options can consistently and confidently be applied and recommended.

 

1. Vereonesi U, et al. Intraoperative radiotherapy versus external radiotherapy for early breat cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol 2013; 14(13) : 1269-77.

2. Daida JS, et al. Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results for local control and overall survival from the TARGIT-A randomised trial. Lancet.2013 Nov 8.

 
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