Is radiotherapy needed after breast conservation for small invasive breast cancers?

The purpose of this study was to determine the rate of local recurrence in patients with small invasive breast cancers (<1 cm) who had been treated with breast-conserving surgery either with (group 1) or without (group 2) adjuvant radiotherapy.

This is a retrospective study of 110 patients with an invasive breast cancer less than 1 cm in size, treated in our centre by breast-conserving surgery. Parameters examined included age at and mode of presentation, histopathological features, adjuvant therapy, length of follow-up and outcome in terms of local recurrence rate and death.

In group 1 there were 59 women of median age 57 (38-80) years. The median tumour size was 9 (1-10) mm and median follow-up was 74 (15-110) months. There were no local recurrences. In group 2 the median age at presentation was 59 (48-81) years. The median tumour size was 7 (2-10) mm and median follow-up was 47 (14-93) months. There were three non-breast-cancer related deaths and three local recurrences (6%).

A local recurrence rate of 6% at almost 4 years median follow-up suggests that it may be possible to avoid adjuvant radiotherapy in a subgroup of largely screen-detected, node-negative patients with invasive tumours less than 1 cm, in whom adequate local excision is performed. Further follow-up is required to substantiate this.