Sentinel Lymph Node Biopsy and Isolated Tumor Cells in Invasive Lobular Versus Ductal Breast Cancer

Update on sentinel node pathology in breast cancer

Pathologic examination of the sentinel lymph nodes (SLNs) in patients with breast cancer has been impacted by the publication of practicing changing trials over the last decade. With evidence from the ACOSOG Z0011 trial to suggest that there is no significant benefit to axillary lymph node dissection (ALND) in early-stage breast cancer patients with up to 2 positive SLNs, the rate of ALND, and in turn, intraoperative evaluation of SLNs has significantly decreased. It is of limited clinical significance to pursue multiple levels and cytokeratin immunohistochemistry to detect occult small metastases, such as isolated tumor cells and micrometastases, in this setting. Patients treated with neoadjuvant therapy, who represent a population with more extensive disease and aggressive tumor biology, were not included in Z0011 and similar trials, and thus, the evidence cannot be extrapolated to them. Recent trials have supported the safety and accuracy of sentinel lymph node biopsy (SLNB) in these patients when clinically node negative at the time of surgery. ALND remains the standard of care for any amount of residual disease in the SLNs and intraoperative evaluation of SLNs is still of value for real time surgical decision making. Given the potential prognostic significance of residual small metastases in treated lymph nodes, as well as the decreased false negative rate with the use of cytokeratin immunohistochemistry (IHC), it may be reasonable to maintain a low threshold for the use of cytokeratin IHC in post-neoadjuvant cases. Further recommendations for patients treated with neoadjuvant therapy await outcomes data from ongoing clinical trials. This review will provide an evidence-based discussion of best practices in SLN evaluation.

Axillary lymph node and non-sentinel lymph node metastasis among the ACOSOG Z0011 eligible breast cancer patients with invasive ductal, invasive lobular, or other histological special types: a multi-institutional retrospective analysis

PURPOSE

Given the histological special types (HST) of breast carcinoma accounted for minority of the Z0011 study population, this study aimed to assess the rates of axillary lymph node (ALN) involvement and non-sentinel lymph node (SLN) metastasis in patients with invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), or other HST.

METHODS

Patients with cT1-2N0M0 breast cancer treated between 2009 and 2018 were retrospectively included from a multi-institutional database. Rates of nodal involvement were analyzed among different histological subgroups. The impact of ALN dissection (ALND) on adjuvant treatment decisions and prognosis were also analyzed among patients with 1-2 + SLNs.

RESULTS

A total of 8294 patients were included: 6854 (82.6%), 257 (3.1%), and 1183 (14.3%) patients with IDC, ILC, and other HST, respectively. IDC patients had a significantly higher rate of ALN metastasis compared with ILC or other HST (31.9% vs. 22.6% vs. 16.4%, P < 0.001). However, in patients with 1-2 + SLNs, rates of non-SLN metastasis were similar among three groups (IDC: n = 182, 28.6% vs. ILC: n = 5, 31.2% vs. other HST: n = 29, 34.9%, P = 0.481). For patients with 1-2 + SLNs, rates of adjuvant chemotherapy and the estimated 3-year recurrence-free survival were similar between the SLN biopsy and ALND arms, regardless of the histological types.

CONCLUSION

Among patients with 1-2 + SLNs, ILC or other HST had similar rates of non-SLN metastasis compared with IDC. Omission of ALND may not influence adjuvant chemotherapy usage or disease outcome regardless of histological types.

Lobular Histology Does Not Predict the Need for Axillary Dissection Among ACOSOG Z0011-Eligible Breast Cancers

BACKGROUND

The American College of Surgeons Oncology Group (ACOSOG) Z0011 trial demonstrated that axillary lymph node dissection (ALND) may be omitted for women with two or fewer positive sentinel nodes (SLNs) undergoing breast-conservation therapy (BCT). Lobular histology comprises a minority of patients, and applicability to these discohesive cancers has been questioned.

METHODS

From August 2010 to March 2017, patients undergoing BCT for cT1-2N0 cancer with positive SLNs were prospectively managed with ALND for three or more positive SLNs or gross extracapsular extension (ECE). In this study, clinicopathologic characteristics and nodal burden were compared between pure/mixed invasive lobular cancer (ILC) and invasive ductal cancer (IDC) patients.

RESULTS

Among 813 consecutive patients, 104 (12.8%) had ILC and 709 (87.2%) had IDC. ILC was more often multifocal and low grade, and less frequently had lymphovascular invasion (all p < 0.001). ILC more often had SLN macrometastases (81.7% ILC vs. 69.4% IDC; p = 0.01) and more than 2 mm of ECE (30.8% ILC vs. 19.5% IDC; p = 0.03), but the proportions of cases with three or more positive SLNs were similar in the two groups (14.4% ILC vs. 9.9% IDC; p = 0.2). The ALND procedure was performed for 20 ILC patients (19.2%) compared with 97 IDC patients (13.7%) (p = 0.2). Additional positive nodes were found in 80% of the ILC patients versus 56.7% of the IDC patients (p = 0.09). The ALND and nodal burden rates were similar in the estrogen receptor-positive (ER+) subset analysis. In the multivariable analysis, lobular histology (p = 0.03) and larger tumors (p = 0.03) were associated with additional positive nodes. During a median follow-up period of 42 months, there were no isolated axillary recurrences.

CONCLUSIONS

Despite a higher proportion of SLN macrometastases and association with more positive nodes at ALND, lobular histology does not predict the need for ALND. ALND is not indicated on the basis of histology among patients otherwise meeting Z0011 criteria.

Lobular Breast Cancer: Different Disease, Different Algorithms?

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer, with a unique pathogenesis and distinct clinical biology. ILCs display a characteristic loss of E-cadherin, are largely estrogen receptor positive, HER2 negative, and low to intermediate grade. These features portend a favorable prognosis, but there is a tendency for late recurrences and atypical metastases. ILCs tend to be insidious and infiltrative, which can pose a challenge for diagnosis, and emerging data suggest they may have a propensity for a differing response to standard therapies.

Complete axillary dissection without drainage for the surgical treatment of breast cancer: a randomized clinical trial

OBJECTIVE:

This randomized clinical trial evaluated the possibility of not draining the axilla following axillary dissection.

METHODS:

The study included 240 breast cancer patients who underwent axillary dissection as part of conservative treatment. The patients were divided into two groups depending on whether or not they were subjected to axillary drainage. ClinicalTrials.gov: NCT01267552.

RESULTS:

The median volume of fluid aspirated was significantly lower in the axillary drainage group (0.00 ml; 0.00 - 270.00) compared to the no drain group (522.50 ml; 130.00 - 1148.75). The median number of aspirations performed during conservative breast cancer treatment was significantly lower in the drainage group (0.5; 0.0 - 4.0) compared to the no drain group (5.0; 3.0 - 7.0). The total volume of serous fluid produced (the volume of fluid obtained from drainage added to the volume of aspirated fluid) was similar in the two groups. Regarding complications, two cases (2.4%) of wound dehiscence occurred in the drainage group compared to 13 cases (13.5%) in the group in which drainage was not performed, with this difference being statistically significant. Rates of infection, necrosis and hematoma were similar in both groups.

CONCLUSION:

Safety rates were similar in both study groups; hence, axillary dissection can feasibly be performed without drainage. However, more needle aspirations could be required, and there could be more cases of wound dehiscence in patients who do not undergo auxiliary drainage.