Trial Information

A Randomised Comparison of Breast Conservation With or Without Lumpectomy Radiotherapy Boost

A boost dose of radiation is commonly but not universally employed in breast conservation
techniques.

The potential disadvantages when a boost is employed include:

- Increased complexity of treatment

- Increased duration of treatment

- Increased travel, social/employment dislocation

- Increased complications

- Worse cosmesis and/or increased breast discomfort

- Increased difficulty in detecting recurrence.

- Prolongation of gap or increased delay for chemotherapy if indicated

The potential advantages of a boost are the following:

- Reduced local failure rates

- Reduced local failure translating to improved survival

- Maximising cosmesis by reducing dose to larger breast volume

None of the potential advantages have been clearly demonstrated in a controlled fashion
although there are sound theoretical reasons that a boost will improve local control.
Holland's landmark paper using radiologic-pathologic correlation of mastectomy specimens,
whilst finding residual foci beyond the boundaries of cosmetically acceptable resection
margins, also found most of the residual tumour relatively close to the index mass. There is
a known dose-response for control of breast cancer. Kurtz reported a doubling of the
longterm recurrence rate when the dose to the tumour bed was less than 75 Gy or delivered
at less than 8 Gy per week from 15% to 30% using telecesium following lumpectomy. Treating
the entire breast to doses above 50 to 54 Gy in 5 weeks is associated with significantly
worse cosmesis, hence the common use of a boost. There are as yet no controlled comparisons
published however Beadle reported a 50% increase in the rates of poor cosmesis when a boost
was employed. Borger has demonstrated that the risk of fibrosis increases fourfold with
every 100 cm3 increase in boost volume. Accurate localisation of the tumour bed for boost
delivery is difficult in the absence of radioopaque clips (uncommonly employed by our
referral base). The use of electrons to deliver the boost has been reported to decrease the
cosmetic outcome compared to I192 because of telangiectasia, although this is controversial
with other reports indicating superior results with electrons, which is the modality
available at St George and Wollongong. The latter avoids hospitalisation. There is at least
one other randomised multicentre study being conducted testing the value of a boost by the
EORTC in Europe but no results are yet available.

Comparisons: Patients will be stratified by chemotherapy (none, AC, non-AC) and within the
non-AC arm will be randomised in respect to timing (pre, sandwich, concurrent) of
radiotherapy. Randomisation to treatment will be - boost (45Gy 25# + 16Gy 8#) or no boost
(50Gy 25#).