Morphometry of Isolated Tumor Cells in Breast Cancer Sentinel Lymph Nodes: Metastases or Displacement?

Papillary Lesions of the Breast: An Update

CONTEXT

-Papillary lesions of the breast, characterized by the presence of arborescent fibrovascular cores that support epithelial proliferation, constitute a heterogeneous group of neoplasms with overlapping clinical manifestation and histomorphologic features, but may have divergent biological behavior. These lesions are exclusively intraductal neoplasms, although an invasive carcinoma may rarely have a predominantly papillary architecture. Although recognition of a papillary architecture is typically not challenging, the histologic distinction of these entities is not always straightforward. Historically, different terminologies and variable criteria have been proposed for a given entity by various authorities. The difficulty in classifying these lesions has been further confounded by the scarcity of data and the heterogeneity across different studies with regard to the molecular genetic characteristics of this group of lesions.

OBJECTIVE

-To provide an overview focusing on the current concepts in the diagnosis and classification of papillary lesions of the breast incorporating recent molecular genetic advances.

DATA SOURCES

-Data were obtained from pertinent peer-reviewed English-language literature.

CONCLUSIONS

-The recent evolution of molecular techniques has enhanced our knowledge of the pathogenesis of papillary carcinomas of the breast. This, along with emerging outcome studies, has led to prognosis-based reclassification of some of these entities. Additional studies focusing on the molecular signatures are needed to identify potential decision tools to further stratify these lesions with respect to prognostic significance.

Is Sentinel Lymph Node Dissection Warranted for Patients with a Diagnosis of Ductal Carcinoma In Situ?

BACKGROUND

Positive sentinel lymph node (SLN) findings in ductal carcinoma in situ (DCIS) range from 1 to 22 % but have unknown biologic significance. This study sought to identify predictors of positive SLNs and to assess their clinical significance for patients with an initial diagnosis of DCIS.

METHODS

The study identified 1234 patients with an initial diagnosis of DCIS who underwent SLN dissection (SLND) at our institution from 1997 through 2011. Positive SLN findings were categorized as isolated tumor cells (ITCs) (≤0.2 mm), micrometastases (>0.2-2 mm), or macrometastases (>2 mm). Predictors of positive SLNs were analyzed, and survival outcomes were examined.

RESULTS

Positive SLN findings were identified in 132 patients (10.7 %): 66 patients with ITCs (5.4 %), 36 patients with micrometastases (2.9 %), and 30 patients with macrometastases (2.4 %). Upstaging to microinvasive (n = 68, 5.5 %) or invasive (n = 259, 21.0 %) cancer occurred for 327 patients (26.5 %). Factors predicting positive SLNs included diagnosis by excisional biopsy (odds ratio [OR] 1.90; P = 0.007), papillary histology (OR 1.77; P = 0.006), DCIS larger than 2 cm (OR 1.55; P = 0.030), more than three interventions before SLND (4 interventions: OR 2.04; P = 0.022; ≥5 interventions: OR 3.87; P < 0.001), and occult invasion (microinvasive: OR 3.44; P = 0.001; invasive: OR 6.21; P < 0.001). The median follow-up period was 61.7 months. Patients who had pure DCIS with and without positive SLNs had equivalent survival rates (100.0 vs 99.7 %; P = 0.679). Patients with occult invasion and positive SLNs had the worst survival rate (91.7 %; P < 0.001).

CONCLUSIONS

Occult invasion and more than three total interventions were the strongest predictors of positive SLN findings in patients with an initial diagnosis of DCIS. This supports the theory of benign mechanical transport of breast epithelial cells. Except for patients at high risk for invasive disease, routine use of SLND in DCIS is not warranted.

False-positive and false-negative sentinel node findings in 473 breast cancers

We reviewed lymph node samples from 473 consecutive breast cancer cases with either negative sentinel nodes or isolated tumor cells to evaluate the rate of false-positive sentinel node findings. Nuclear morphometry was applied to compare nuclear atypia between the primary tumor and metastases classified as isolated tumor cells by size. In addition, the role of the diagnostic preoperative biopsy method, either core needle biopsy or fine needle aspiration cytology, on the prevalence of isolated tumor cells was investigated. In addition, we studied the expression of metastasis-associated protein 1 in the primary tumor and corresponding metastases in 95 cases, including 52 isolated tumor cell cases, to distinguish a true metastasis from a benign epithelial displacement. Our review revealed 4 false positives and 7 false negatives from 473 sentinel node cases. In addition, 5 true-positive cases were upstaged from isolated tumor cells to micrometastases. No association was found between the preoperative biopsy method and the sentinel node status (P=.859). There was no difference in nuclear atypia, when the cells in isolated tumor cells and primary tumor were compared. Therefore, small metastases do not represent benign epithelial displacement. Isolated tumor cell findings did not correlate with preoperative biopsy methods. The metastasis-associated protein 1 staining score sum was lower in the metastases than in the primary tumor in 72% of cases, including all sizes of metastases. These data suggest that metastasis-associated protein 1 staining is not ideal for investigating the possible malignant nature of smaller metastases because of the relatively low concordance between the primary tumor and metastases, even macrometastases.

Prognostic impact of isolated tumor cells in breast cancer axillary nodes: single tumor cell(s) versus tumor cell cluster(s) and microanatomic location

In breast cancer, it has been shown that pN0(i+) and pN1mi have a comparable negative impact on disease-free survival, compared with pN0. However, pN0(i+) is considered to be a heterogeneous group. We determined the effect of metastatic size and microanatomic location within the pN0(i+) group on breast cancer recurrence. We included all Dutch breast cancer patients diagnosed in 1998-2005 with favorable primary tumor characteristics and a final nodal status of pN0(i+). For this analysis, only patients without adjuvant systemic therapy were eligible (n = 513). Presence of single tumor cells versus cell clusters, metastatic size and microanatomic location were recorded. Primary endpoint was disease-free survival. Analyses were adjusted for age at diagnosis, tumor size, tumor grade, axillary treatment and hormone receptor status. The 5-year disease-free survival of patients with single tumor cell(s) (n = 93) was 78.6% and with tumor cell cluster(s) (n = 404) 77.1%. The hazard ratio for disease events was 1.05 (95% CI 0.63-1.76) for cell cluster(s) compared with single cell(s). In a Cox regression model, doubling of metastatic tumor size corresponded to a hazard ratio of 1.21 (95% CI 1.02-1.43). The adjusted hazard ratio was 0.90 (95% CI 0.54-1.50) for parenchymal (n = 112) versus sinusoidal location (n = 395). Single tumor cells bear similar prognostic information as small tumor cell clusters, even though results do suggest that within the pN0(i+) group, increasing size of nodal involvement is associated with reduced survival. Microanatomic location does not seem to have prognostic relevance.

Iatrogenic displacement of tumor cells to the sentinel node after surgical excision in primary breast cancer

Isolated tumor cells (ITC) are more common in the sentinel node (SN) after needle biopsy of a breast cancer, indicating iatrogenic displacement of tumor cells. We here investigate whether similar iatrogenic displacement occurs after surgical excision of a breast tumor. We compared the incidence of ITC in the SN of 414 breast cancer patients with recent surgical excision to a group of 16,960 patients without recent surgical procedure in a multivariate analysis by linking data from the Danish Breast Cancer Cooperative Group database and the Danish National Health Register. Moreover, the incidence of spread to non-SNs in patients with ITC in the SN after recent surgical excision was analyzed. We found an adjusted odds ratio on 3.73 (95% CI 2.57-5.43; P < 0.0001) for having ITC in the SN after surgical excision. The increase in ITC after surgical excision was especially seen in patients with ductal carcinomas (OR 4.66; 95% CI 3.03-7.19). None of the patients with ITC in SN after surgical excision had further spread to non-SNs compared to 12% in the group without recent surgical excision (P = 0.09). The nearly fourfold increase in ITC in the SN after surgical excision indicates that this procedure induces iatrogenic displacement of tumor cells. This displacement was more common in ductal carcinomas. We found no further dissemination to non-SNs in patients with ITC in the SN after recent surgical excision, and it is questioned whether these patients benefit from an axillary lymph node dissection.

Micrometastases or isolated tumor cells and the outcome of breast cancer

BACKGROUND

The association of isolated tumor cells and micrometastases in regional lymph nodes with the clinical outcome of breast cancer is unclear.

METHODS

We identified all patients in The Netherlands who underwent a sentinel-node biopsy for breast cancer before 2006 and had breast cancer with favorable primary-tumor characteristics and isolated tumor cells or micrometastases in the regional lymph nodes. Patients with node-negative disease were randomly selected from the years 2000 and 2001. The primary end point was disease-free survival.

RESULTS

We identified 856 patients with node-negative disease who had not received systemic adjuvant therapy (the node-negative, no-adjuvant-therapy cohort), 856 patients with isolated tumor cells or micrometastases who had not received systemic adjuvant therapy (the node-positive, no-adjuvant-therapy cohort), and 995 patients with isolated tumor cells or micrometastases who had received such treatment (the node-positive, adjuvant-therapy cohort). The median follow-up was 5.1 years. The adjusted hazard ratio for disease events among patients with isolated tumor cells who did not receive systemic therapy, as compared with women with node-negative disease, was 1.50 (95% confidence interval [CI], 1.15 to 1.94); among patients with micrometastases, the adjusted hazard ratio was 1.56 (95% CI, 1.15 to 2.13). Among patients with isolated tumor cells or micrometastases, the adjusted hazard ratio was 0.57 (95% CI, 0.45 to 0.73) in the node-positive, adjuvant-therapy cohort, as compared with the node-positive, no-adjuvant-therapy cohort.

CONCLUSIONS

Isolated tumor cells or micrometastases in regional lymph nodes were associated with a reduced 5-year rate of disease-free survival among women with favorable early-stage breast cancer who did not receive adjuvant therapy. In patients with isolated tumor cells or micrometastases who received adjuvant therapy, disease-free survival was improved.