Trial Information

Pilot for a Randomised Comparison of Anastrozole Commenced Before and Continued During Adjuvant Radiotherapy for Breast Cancer Versus Anastrozole and Subsequent Ant-Oestrogen Therapy Delayed Until After Radiotherapy

Adjuvant radiotherapy is well established as the primary modality to enhance local control
in breast cancer. The use of adjuvant hormone therapy such as tamoxifen has shown to improve
local control to a relatively minor amount on its own and does enhance local control of
adjuvant radiotherapy. There is however, conflicting in vitro and clinical data regarding
the effects of different sequences on tamoxifen and radiotherapy in terms of both local
control and enhancement of radiotherapy toxicities.

Aromatase inhibitors such as anastrazole are establishing themselves as a class of drug
superior to tamoxifen for the control of estrogen dependent breast cancers and overall are
better tolerated with the exception of greater bone loss.

As the key question is whether the sequencing of the aromatase inhibitor anastrozole alters
local control by acting as an enhancer of the radiation breast cancer cell kill, it is
therefore the aim of this study to compare 3 months of anastrozole prior to radiotherapy
versus 3 months of anastrozole after radiotherapy with a specific objective of reducing the
baseline ratio of in- field radiotherapy failure from 6% to 3%.This pilot study is
preliminary to a planned long term study to investigate local failure.

For the pilot a period of 6 months with all contributing centres open will provide a good
test of recruitment matching estimates. 100 patients will provide a good sample to compare
to the 270 tamoxifen treated women in the breast boost study for quality of life. It will
also provide a 95% CI on the proportion of complying women in the order of ± 5% if 85 to 90
% of women comply.