Margin status and the risk of local recurrence after breast-conserving treatment of lobular breast cancer.

BACKGROUND: Invasive lobular breast carcinoma is known for its multicentricity and is associated with a higher incidence of incomplete excision after breast-conserving therapy. The aim of the study was to examine the influence of positive surgical margins on the local recurrence rate in patients diagnosed with invasive lobular cancer and treated with breast-conserving therapy.
METHODS: All 416 women diagnosed with invasive lobular breast cancer and undergoing breast-conserving treatment between 1995 and 2002 were selected from the population-based Eindhoven Cancer Registry. Their medical charts were reviewed and detailed information was collected.
RESULTS: The risk of margin involvement was 29% after the first operation and 17% when taking into account the final margin status of the patients undergoing re-excision. During follow-up, 18 patients developed a local recurrence. The 5 year actuarial risk of developing a local recurrence was 3.5% (95% confidence interval 2.5-4.5) and the 8 year risk was 6.4% (95% confidence interval 4.7-8.0). There was no influence of positive surgical margins on the risk of local recurrence, neither in the univariate analysis nor after adjustment for age, tumour size, nodal status and adjuvant systemic treatment.
CONCLUSION: Patients with invasive lobular cancer, treated with breast-conservation, have a low risk of local recurrence, despite their high risk of having a microscopically incomplete excision of the tumour.