Effectiveness of Neoadjuvant Letrozole of Invasive Lobular Cancers

Background:Invasive lobular cancers are poorly responsive to neoadjuvant chemotherapy. They are commonly hormone sensitive. This study set out to investigate the efficacy of neoadjuvant letrozole in post-menopausal women with large operable or locally advanced breast cancers.Patients and Methods:48 consecutive patients with large operable or locally advanced invasive lobular ER positive (Allred score 8 = 38, 7 =8, 6=1, 5=1) were treated in a single Breast Unit by neoadjuvant letrozole for 3 months or longer. The mean age was 76.7 years with a range of 55 to 91 years. 6 tumours measured >2-4 cm (T2), 26 tumours measured >4 cm (T2, T3) and 16 were locally advanced (T4). Response was assessed by a single observer at 3 months.Results:Response to TreatmentThe mean reduction in clinical volume at 3 months was 60% (95% CI 50-79%) with a median of 67% (95% CI 60-79%). Responses were classified as 1 Complete Response (CR), 25 Partial Response (PR), 16 Minimal Response (MR), 4 Stable Disease (SD) and 2 Progression.The mean USS in volume was 69% (60-78%), with a median of median 80% (66-84%). Response was classified as CR= 12, PR = 25, MR = 7, SD = 3 and Progression = 1.Surgery and Outcome32 have come to surgery and 16 have continued on letrozole.24 patients were considered suitable for breast conserving surgery (WLE) of whom 16 successful had WLE (67% with Clear Margins), 4 had a WLE and then a successful re- excision of margins and 4 had a WLE followed by mastectomy. The final rate of successful breast conservation was thus 20/24 (83%).8 patients with locally advanced breast cancer became operable and were treated by mastectomy.SummaryThis is the largest series of invasive lobular carcinomas treated by neoadjuvant letrozole ever reported.Invasive lobular carcinomas are often large at diagnosis.They are mainly ER rich.In post-menopausal women they respond well to endocrine therapy with letrozole.Neoadjuvant therapy with letrozole allows many women with large invasive lobular carcinomas to be treated successfully with breast conservation.This contrasts with the poor results obtained with neoadjuvant chemotherapy.ConclusionNeoadjuvant letrozole therapy is an effective treatment for shrinking invasive lobular ER positive breast cancers in post-menopausal women. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1085.