Robust and validated models to predict high risk of non-sentinel node metastases in breast cancer patients with micrometastases or isolated tumor cells in the sentinel node

Critical review of axillary recurrence in early breast cancer

Around 2% of early breast cancer cases treated with axillary lymph node dissection (ALND) underwent axillary recurrence (AR) and it has a deleterious effect in prognosis. Different scenarios have incorporated Sentinel Lymph Node (SLN) Biopsy (SLNB) instead of ALND as part of the standard treatment and more effective systemic treatment has also been incorporated in routine management after first curative surgery and after regional recurrence. However, there is concern about the effect of SLNB alone over AR risk and how to predict and treat AR. SLN biopsy (SLNB) has been largely accepted as a valid option for SLN-negative cases, and recent prospective studies have demonstrated that it is also safe for some SLN-positive cases and both scenarios carry low AR rates. Different studies have identified clinicopathological factors related to aggressiveness as well as high-risk molecular signatures can predict the development of locoregional recurrence. Other publications have evaluated factors affecting prognosis after AR and find that time between initial treatment and AR as well as tumor aggressive behavior influence patient survival. Retrospective and prospective studies indicate that treatment of AR should include local and systemic treatment for a limited time.

Locoregional treatment of early breast cancer with isolated tumor cells or micrometastases on sentinel lymph node biopsy

The advent of sentinel lymph-node technique has led to a shift in lymph-node staging, due to the emergence of new entities namely micrometastases (pN1mi) and isolated tumor cells [pN0(i+)]. The prognostic significance of this low positivity in axillary lymph nodes is currently debated, as is, therefore its management. This article provides updates evidence-based medicine data to take into account for treatment decision-making in this setting, discussing the locoregional treatment in pN0(i+) and pN1mi patients (completion axillary dissection, axillary irradiation with or without regional nodes irradiation, or observation), according to systemic treatment, with the goal to help physicians in their daily practice.

Survival impact and predictive factors of axillary recurrence after sentinel biopsy

BACKGROUND

The rate of axillary recurrence (AR) after sentinel lymph node biopsy is usually low but few studies investigated its impact on survival. Our aim was to determine the rate and predictive factors of AR in a large cohort of breast cancer patients and its impact on survival.

PATIENTS AND METHODS

From 1999 to 2013, 14,095 patients who underwent surgery for clinically N0 previously untreated breast cancer and had sentinel lymph node biopsy were analysed. A simplified score predictive of AR was established.

RESULTS

Median follow-up was 55.2 months. AR was observed in 0.51% of cases, with a median time to onset of 43.4 months. In multivariate analysis, the occurrence of AR was significantly correlated with grade 2 or 3 disease, absence of radiotherapy and tumour subtype (hormonal receptor [HR]- / human estrogen receptor [HER]+). AR rates were 1% for triple-negative tumours, 2.8% for HER2-positive tumours, 0.4% for luminal A tumours, 0.9% for HER2-negative luminal B tumours, and 0.5% for HER2-positive luminal B tumours. A simplified score predictive of the occurrence of AR was established. Patients could be divided into three different score groups (p < 0.0001). In multivariate analysis, overall survival was significantly lower in cases of AR (p < 0.0001), age >50, lymphovascular invasion, grade 3 disease, sentinel node (SN) macrometastases, tumour size >20 mm, absence of chemotherapy and triple-negative phenotype. Survival in patients with AR was significantly lower in case of early-onset (2 years) AR (p = 0.017).

CONCLUSIONS

Isolated AR is more common in Her2-positive/HR-negative triple-negative tumours with a more severe prognosis in triple-negative and Her2-positive/HR-negative tumours, and represents an independent adverse factor justifying an indication for systemic treatment for AR treatment. However, the benefit of any systemic treatment remains to be proven.

Risk of non-sentinel node metastases in patients with symptomatic cancers compared to screen-detected breast cancers

BACKGROUND

Symptomatic breast cancers may be more aggressive as compared to screen-detected breast cancers. This could favor axillary lymph node dissection (ALND) in patients with symptomatic breast cancer and positive sentinel nodes.

METHOD

We identified 955 patients registered in the Danish Breast Cancer Cooperative Group (DBCG) Database in 2008 - 2010 with micrometastases (773) or isolated tumor cells (ITC) (182) in the sentinel node. Patients were cross-checked in the Danish Quality Database of Mammography Screening and 481 patients were identified as screen-detected cancers. The remaining 474 patients were considered as having symptomatic cancers. Multivariate analyses of the risk of non-sentinel node metastases were performed including known risk factors for non-sentinel node metastases as well as method of detection.

RESULTS

18% of the patients had metastases in non-sentinel nodes. This was evenly distributed between patients with symptomatic and screen-detected cancers; 18.5% vs 17.5% (OR 1.07; 95% CI 0.77-1.49; p = 0.69). In patients with micrometastases 21% had non-sentinel node metastases in the group with symptomatic cancers compared to 19% of patients with screen-detected cancers. This difference was not significant (OR 1.16; 95% CI 0.81-1.65, p = 0.43). Neither the multivariate analysis showed an increased risk of non-sentinel node metastases in patients with symptomatic cancers compared to screen-detected cancers (OR 1.12, CI 0.77-1.62, p = 0.55). In patients with ITCs 8% of patients with symptomatic cancers had non-sentinel node metastases compared to 13% of patients with screen-detected cancers. This difference was not significant (OR 0.58; 95% CI 0.22-1.54, p = 0.27). In the multivariate analysis, the risk of non-sentinel node metastases was still not significantly increased in patients with symptomatic cancers compared to screen-detected cancers (OR 0.45; 95% CI 0.16-1.27, p = 0.13).

CONCLUSION

We did not find any clinically relevant difference in the risk of non-sentinel node metastases between patients with symptomatic and screen-detected cancers with micrometastases or ITC in the sentinel node.

[Regional treatment for axillary lymph node micrometastases of breast cancer]

In patients with breast cancer, axillary lymph node micrometastasis detection has been more frequent with a better definition since the introduction of the sentinel node procedure. In this review, we focus on pN1mi micrometastasis and review the literature in order to determine factors involved in making the decision of a regional treatment.

Cross-validation of three predictive tools for non-sentinel node metastases in breast cancer patients with micrometastases or isolated tumor cells in the sentinel node

BACKGROUND

We cross-validated three existing models for the prediction of non-sentinel node metastases in patients with micrometastases or isolated tumor cells (ITC) in the sentinel node, developed in Danish and Finnish cohorts of breast cancer patients, to find the best model to identify patients who might benefit from further axillary treatment.

MATERIAL AND METHOD

Based on 484 Finnish breast cancer patients with micrometastases or ITC in sentinel node a model has been developed for the prediction of non-sentinel node metastases. Likewise, two separate models have been developed in 1577 Danish patients with micrometastases and 304 Danish patients with ITC, respectively. The models were cross-validated in the opposite cohort.

RESULTS

The Danish model for micrometatases was accurate when tested in the Finnish cohort, with a slight change in AUC from 0.64 to 0.63. The AUC of the Finnish model decreased from 0.68 to 0.58 when tested in the Danish cohort, and the AUC of the Danish model for ITC decreased from 0.73 to 0.52, when tested in the Finnish cohort. The Danish micrometastatic model identified 14-22% of the patients as high-risk patients with over 30% risk of non-sentinel node metastases while less than 1% was identified by the Finish model. In contrast, the Finish model predicted a much larger proportion of patients being in the low-risk group with less than 10% risk of non-sentinel node metastases.

CONCLUSION

The Danish model for micrometastases worked well in predicting high risk of non-sentinel node metastases and was accurate under external validation.