Stick or switch? Audit of the use of switch therapy from tamoxifen to an aromatase inhibitor in breast cancer

Introduction

Tamoxifen has an established role as the standard adjuvant therapy for early oestrogen-receptor-positive breast cancer. Aromatase inhibitors are now licensed for adjuvant treatment following 2 to 3 years of tamoxifen. This switch therapy offers both disease-free and modest overall survival advantages compared with 5 years of tamoxifen [1]. Greater Midlands Cancer Network guidelines based on NICE guidelines (2006) recommend switch therapy in patients who are not at low risk of recurrence [2]. There are no reports in the literature to indicate whether this is currently happening in clinical practice. We examined our own patient population to see if high-risk patients were being switched appropriately.

Methods

Retrospective audit of all females diagnosed with invasive breast carcinoma between July 2006 and December 2007 at the University Hospital of North Staffordshire.

Results

Of the 291 women diagnosed with invasive breast cancer, 13 fulfilled the inclusion criteria. Forty-six per cent of these were switched appropriately. In the remaining 54% of cases a switch had not been considered.

Conclusions

More than one-half of the women receiving adjuvant tamoxifen are not being considered for a switch, which puts them at an increased risk of disease recurrence. Factors identified by the audit that could be modified to improve practice are: highlighting the tamoxifen start date in the patient notes to enable the reviewing clinician to more easily identify when a switch is due, and clearer ownership of ongoing adjuvant therapy between surgeons and oncologists.