Treatment of infra-centimetric HER2-positive(+) invasive breast tumors. The Institut Curie experience.
Authors: Cottu PH , Rodrigues MJ , Kirova Y , Vincent-Salomon A ,   on Behalf of the Institut Curie Breast Cancer Group
Published: December 2010

Abstract #3152

Background: According to the adjuvant trastuzumab (T) trials, node-positive infracentimetric tumors stand for around 7% of all HER2+ breast carcinomas. The benefit of adjuvant T for women with node positive or supracentrimetric HER2+ breast tumors is established. There are no firm data establishing efficacy of T for infracentrimetric node-negative HER2+ tumors. We report our experience on infracentimetric tumors describing the received treatment, its efficacy and tolerance and the criteria that lead to therapeutic decision. Methods: We retrospectively reviewed electronic records of patients (pts) with invasive infra-centimetric HER2+ breast tumors treated in our institution from 2000 to 2008. Clinical, pathological, biological and therapeutic data were assessed. Tumors with a majority (≥80%) of ductal carcinoma in situ (DCIS) were excluded from this analysis. Results: 43 case records have been evaluated. Median age at diagnosis was 56 years (31-84). All tumors were treated by local surgery. 11 pts (26%) had node-positive tumors when including pN0i+ and pNmi+ tumors. 9 pts (82%) had local irradiation. A majority (n=8, 73%) were treated by chemotherapy and T except 1 with a pN0i+ tumor and 2 pts treated before T approval (2000-2001).32 pts (74%) had pN0 tumors. Ductal carcinomas accounted for 91% of tumors (n=29), and 14 (44%) were hormonal receptors-negative. Radiotherapy was given in 28 (88%) of them. 8 (29%) had nodal irradiation covering internal mammar chains, infra and supraclavicular regions. 21 of these pts (75%), had a 16 Gy breast tumor bed boost. Half the pts had chemotherapy (n=16). A sequential anthracycline/taxan (ATx)regimen was chosen for 10 pts (63%). Other regimen were A-based for 5 pts (31%) and Tx-based for 1 pt (6%). 1 pt developped myocardial infarction after her third anthracycline cycle. 22 pts (69%) have been treated with T. 13 of them have been treated by a chemotherapy/T (59%) combination. No significant correlation was found between decision of systemic treatment and age, hormone receptor status, grade, mitotic index or lymphovascu lar emboles. T treatment was complicated for 2 pts (13%) by left ventricular ejection fraction diminution under 50% after 5 and 6 months.With a median follow-up of 18 months, none of the 43 pts have developed recurrent invasive disease. In one pure micropapillary case, in situ local recurrence with micro-infiltration was seen at 5 years.Conclusion: In our experience, almost all pts were treated by local surgery and radiotherapy and around half pts received T since its approval with no significative clinical nor pathological factor leading to this decision. Usefulness of adjuvant chemotherapy and T for this tumors should be analyzed with data from prospective ongoing or closed trials. Systemic adjuvant treatment should be proposed for stage II tumors and discussed for smaller tumors taking into account age, grade, mitotic index, hormonal receptors status and presence of vascular invasion.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3152.