Do isolated cells (pN0i+) in the sentinel lymph node change the post-operative management in breast cancer?.

Abstract

Abstract Abstract #206 Background: immunohistochemical (IHC) analysis of the sentinel lymph node (SLN) allows detection of occult metastases not routinely diagnosed by conventional techniques. There is, however, no consensus concerning the post-operative management of those patients with IHC-positive (pN0i+) nodes: should one re-operate, change the medical treatment or alter the irradiation fields?
 Patients and methods: 2692 patients with early invasive breast cancer underwent conservative treatment with SLN biopsy between 2000 and 2006. SLN were evaluated with frozen section followed by serial-section HES and IHC if HES showed no tumour cells. Lymph node staging followed the accepted pTNM classification: pN0, pN0i+ (≤ 0.2mm, IHC+), pNmi (0.2-2mm) and pN1a (> 2mm). In 1506 patients with T1pN0 tumours : 143 were pN0i+, that is 10%. We compared the post-operative management of pN0 patients, who had no completion axillary dissection (CAD), to those pN0i+ who did. All positive SLNs underwent CAD according to our institutional protocol.
 Results: 15 of 143 (10.5%) pN0i+ patients showed metastases in their CAD; a single node in 10 cases, 2-3 in 4 and > 3 in one patient. Univariate analysis showed chemo- and hormono-therapy to be more frequently administered in pN0i+ (24.5% vs. 77.6%) compared to pN0 (9.1% vs. 55.8%) patients; p < 0.0001. Irrespective of the result of CAD, pN0i+ patients had significant modifications in their fields of lymphatic irradiation at the internal mammary (43.6% vs. 23.5%), supra-clavicular (40.9% vs. 21.5%) and sub-clavicular (13.5% vs. 3.7%) areas; p < 0.0001. Other predictive factors showed a similar pattern including age < 50 years (31.5% vs. 18.6%), tumour size bigger (1.51cm vs. 1.16 cm) and lymphovascular invasion (27.5% vs. 11.6%); p < 0,0001. After multivariate analysis, the sole decisive factor for chemotherapy between the two groups was the presence of nodal metastasis in CAD. The duration of this study is, however, insufficient to comment on the long-term implications for pN0i+ patients.
 Discussion: immunohistochemistry alone plays a decisive role in favour of chemotherapy in N+ supplementary AD in only 10% of pN0i+ (15/143) patients. However, this concerns only 1% (15/1506) of those undergoing IHC so may have significant resource implications and other factors were found to be more influential. Moreover, pN0i+ patients underwent additional lymphatic irradiation, to all 3 fields, more frequently. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 206.