Between November 2000 and May 2008, data were collected prospectively regarding 1004 consecutive patients who underwent surgical treatment using SLNB as a staging procedure for clinically staged T1–2N0 breast cancer. For the present study, patients were selected who underwent FS analysis of axillary SLNs.
The study group consisted of 879 patients since 125 patients did not undergo FS analysis and were therefore excluded from further analysis. Reasons for not performing FS analysis of SLNs were: small size of the SLNs, that is, when the pathologists deemed the SLNs to small or to fatty for reliable FS analysis (n
= 64), the introduction of this new staging technique when SLNB was followed by ALND on a routine basis (n
= 30), clinical trial participation obviating ALND (assignment to the radiotherapy arm of the AMAROS trial, n
= 26), or inability to retrieve a visualized axillary SLN (n
= 5; the surgical success rate of SLN retrieval was 99.4%).5
For the SLNB a 1-day protocol was used. The visualization and identification of SLNs consisted of preoperative lymphoscintigraphy and the intraoperative use of a γ-ray detection probe together with patent blue dye (Bleu patenté V, Laboratoire Guerbet, Aulnay-sous-Bois, France). Injections were given peritumorally and subcutaneously directly above the tumor. In nonpalpable breast tumors injections were guided by an ultrasound probe or a radiologically placed wire. Imaging was done directly after the nanocolloid injection and 2 h later. In the afternoon of the same day patients were operated on. Axillary SLNs were retrieved first and sent for FS analysis. Subsequently, internal mammary (IM) SLNs were collected when visualized on preoperative lymphoscintigraphy. These internal mammary SLNs were not sent for FS analysis. Detailed information about this procedure was published previously.6
In the pathology department the SLNs were isolated from fatty tissue, bisected longitudinally, separately formalin-fixed, paraffin embedded, and frozen in liquid nitrogen. The first complete cut from both halves was stained with hematoxylin and eosin (H&E) and examined for the presence of metastases by the pathologist. The result of the FS analysis was reported to the operating surgeon a median 22 min after removal of the axillary SLNs and usually before the surgery for the primary breast tumor was completed. If FS confirmed the presence of metastases in the SLN, an ALND was done. An ALND consisted of the removal of all axillary fat from levels I and II and as much as from level III as could be obtained through the axillary incision.
Postoperatively, the remaining tissue of the axillary SLNs and IM SLNs were fixated in formalin and embedded in paraffin. The presence of lymph node metastases was investigated by examining 5 cuts from both halves of the node, 250 μm apart, with H&E and immunohistochemical techniques staining for cytokeratin-8 (IHC). The examining pathologist assessed tumor diameter, the adjusted Bloom Richardson grade (BR-grade), Mitotic Activity Index (MAI), hormonal receptor status (estrogen receptor (ER), and progesterone receptor (PR)) for all patients and HER2/neu status from 2004 on.7
The presence of lymph node metastases was classified according to the 2002 version of the UICC-TNM-classification.8
When the intraoperative FS did not show metastases but the definitive histology did reveal lymph node metastases, patients were advised to undergo a second operation to perform a complementary ALND. Lymph nodes from the complementary ALND specimen were fixated in formalin, embedded in paraffin, and 2 cuts from the center of the node were examined after staining with H&E and IHC.
The indication for subsequent nonsurgical treatment was determined applying the Dutch national guidelines (2008, version 1.1).9
In summary: (1) Adjuvant systemic chemotherapy is advocated in patients younger than 70 years and in the presence of lymph node (macro) metastases, or when the tumor diameter exceeds 2 cm, or when the tumor is larger than 1 cm and the BR grade is II or III. (2) Adjuvant hormonal therapy is advocated under similar conditions, given ER-positive status of the tumor, but irrespective of age. (3) Radiotherapy other than as part of breast-conserving therapy and irrespective of tumor size is indicated when ≥ 4 axillary lymph nodes or level III axillary lymph nodes contain metastases. Locoregional radiotherapy is then advocated. When IM SLNs contain metastases (and axillary SLNs not) radiotherapy of the parasternal and midclavicular field is indicated. Follow-up started at the date of the first operative procedure. Dates of death and locoregional recurrence were recorded prospectively until the last patient visit between October 2007 and May 2008.
The frequency of a “positive” FS result, that is, SLN metastases present, and the frequency of discordance between the intraoperative FS result “no metastasis” and the finding of lymph node metastases in the formalin-fixated and cytokeratin-stained additional cuts of the SLN were assessed. The metastatic burden in the 2 groups, reflected in the respective TNM N classes was compared using chi-square analysis.
Then, for patients who underwent a postponed ALND after a discordant FS result, the proportion of patients with additional lymph node metastases was analyzed as well as the proportion of these latter patients with an increased TNM N class. The advice for subsequent nonsurgical treatment was determined after the first operation and again after the postponed ALND, and we evaluated how often the complementary ALND led to adjustment of nonsurgical treatment.
Lastly, we compared cumulative overall survival and the occurrence of locoregional relapses for the 3 groups delineated by the FS and the definitive pathology examination result.