The impact of postmastectomy radiotherapy on local control in patients with invasive lobular breast cancer.

Purpose: The aim of this population-based study was to examine the impact of postmastectomy radiotherapy on the risk of local recurrence in patients with invasive lobular breast cancer (ILC).
Methods: The population-based Eindhoven Cancer Registry was used to select all patients with ILC, who underwent mastectomy in five general hospitals in the southern part of the Netherlands between 1995 and 2002. Of the 499 patients 383 patients fulfilled the eligibility criteria. Of these patients, 170 (44.4%) had received postmastectomy radiotherapy. The median follow-up was 7.2 years. Fourteen patients (3.7%) were lost to follow-up.
Results: During follow-up 22 patients developed a local recurrence, of whom 4 had received postmastectomy radiotherapy. The 5-year actuarial risk of local recurrence was 2.1% for the patients with and 8.7% for the patients without postmastectomy radiotherapy. After adjustment for age at diagnosis, tumour stage and adjuvant systemic treatment, the patients who underwent postmastectomy radiotherapy were found to have a more than 3 times lower risk of local recurrence compared to the patients without (Hazard Ratio 0.30; 95% Confidence Interval: 0.10-0.89).
Conclusion: Local control is excellent for patients with ILC who undergo postmastectomy radiotherapy and significantly better than for patients not receiving radiotherapy.