Neoadjuvant Model for Testing Emerging Targeted Therapies in Breast Cancer

The current staging and classification systems of breast cancer and their pitfalls: Is it possible to integrate the complexity of this neoplasm into a unified staging system?

Breast cancer is one of the leading causes of cancer death in women worldwide due to its variable aggressiveness and high propensity to develop distant metastases. The staging can be performed clinically or pathologically, generating the stage stratification by the TNM (T - tumor size; N- lymph node metastasis; M - distant organ metastasis) system. However, cancers with virtually identical TNM characteristics can present highly contrasting behaviors due to the divergence of molecular profiles. This review focuses on the histopathological nuances and molecular understanding of breast cancer through the profiling of gene and protein expression, culminating in improvements promoted by the integration of this information into the traditional staging system. As a culminating point, it will highlight predictive statistical tools for genomic risks and decision algorithms as a possible solution to integrate the various systems because they have the potential to reduce the indications for such tests, serving as a funnel in association with staging and previous classification.

Benefit of adjuvant chemotherapy in patients with special histology subtypes of triple-negative breast cancer: a systematic review

PURPOSE

Breast cancer (BC) is a leading cause of morbidity, disability, and mortality in women, worldwide; triple-negative BC (TNBC) is a subtype traditionally associated with poorer prognosis. TNBC special histology subtypes present distinct clinical and molecular features and sensitivity to antineoplastic treatments. However, no consensus has been defined on the best adjuvant therapy. The aim of the review is to study the evidence from literature to inform the choice of adjuvant treatments in this setting.

METHODS

We systematically searched literature assessing the benefit of adjuvant chemotherapy in patients with TNBC special histotypes (PROSPERO: CRD42020153818).

RESULTS

We screened 6404 records (15 included). All the studies estimated the benefit of different chemotherapy regimens, in retrospective cohorts (median size: 69 patients (range min-max: 17-5142); median follow-up: 51 months (range: 21-268); mostly in Europe and USA). In patients with early-stage adenoid cystic TNBC, a marginal role of chemotherapy was reported. Similar for apocrine TNBC. Medullary tumors exhibited an intrinsic good prognosis with a limited role of chemotherapy, suggested to be modulated by the presence of tumor-infiltrating lymphocytes. A significant impact of chemotherapy on the overall survival was estimated in patients with metaplastic TNBC. Limitations were related to the retrospective design of all the studies and heterogeneous treatments received by the patients.

CONCLUSIONS

There is potential opportunity to consider treatment de-escalation and less intense therapies in some patients with early, special histology-type TNBC. International efforts are indispensable to validate prospective clinical decision models.

Breast-Conserving Therapy in Patients with cT3 Breast Cancer with Good Response to Neoadjuvant Systemic Therapy Results in Excellent Local Control: A Comprehensive Cancer Center Experience

BACKGROUND

Many cT3 breast cancer patients are treated with mastectomy, regardless of response to neoadjuvant systemic therapy (NST). We evaluated local control of cT3 patients undergoing breast-conserving therapy (BCT) based on magnetic resonance imaging (MRI) evaluation post-NST. In addition, we analyzed predictive characteristics for positive margins after breast-conserving surgery (BCS).

METHODS

All cT3 breast cancer patients who underwent BCS after NST between 2002 and 2015 at the Netherlands Cancer Institute were included. Local recurrence-free interval (LRFI) was estimated using the Kaplan-Meier method, and predictors for positive margins were analyzed using univariable analysis and multivariable logistic regression.

RESULTS

Of 114 patients undergoing BCS post-NST, 75 had negative margins, 16 had focally positive margins, and 23 had positive margins. Of those with (focally) positive margins, 12 underwent radiotherapy, 6 underwent re-excision, and 21 underwent mastectomy. Finally, 93/114 patients were treated with BCT (82%), with an LRFI of 95.9% (95% confidence interval [CI] 91.5-100%) after a median follow-up of 7 years. Predictors for positive margins in univariable analysis were hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) subtype, lobular carcinoma, and non-mass enhancement (NME) on pre-NST MRI. MRI response was not correlated to positive margins. In multivariable regression, the odds of positive margins were decreased in patients with HER2-positive (HER2+; odds ratio [OR] 0.27, 95% CI 0.10-0.73; p = 0.01) and TN tumors (OR 0.17, 95% CI 0.03-0.82; p = 0.028). A trend toward positive margins was observed in patients with NME (OR 2.38, 95% CI 0.98-5.77; p = 0.055).

CONCLUSION

BCT could be performed in 82% of cT3 patients in whom BCT appeared feasible on post-NST MRI. Local control in these patients was excellent. In those patients with HR+/HER2- tumors, NME on MRI, or invasive lobular carcinoma, the risk of positive margins should be considered preoperatively.

Current Landscape of Breast Cancer Imaging and Potential Quantitative Imaging Markers of Response in ER-Positive Breast Cancers Treated with Neoadjuvant Therapy

In recent years, neoadjuvant treatment trials have shown that breast cancer subtypes identified on the basis of genomic and/or molecular signatures exhibit different response rates and recurrence outcomes, with the implication that subtype-specific treatment approaches are needed. Estrogen receptor-positive (ER+) breast cancers present a unique set of challenges for determining optimal neoadjuvant treatment approaches. There is increased recognition that not all ER+ breast cancers benefit from chemotherapy, and that there may be a subset of ER+ breast cancers that can be treated effectively using endocrine therapies alone. With this uncertainty, there is a need to improve the assessment and to optimize the treatment of ER+ breast cancers. While pathology-based markers offer a snapshot of tumor response to neoadjuvant therapy, non-invasive imaging of the ER disease in response to treatment would provide broader insights into tumor heterogeneity, ER biology, and the timing of surrogate endpoint measurements. In this review, we provide an overview of the current landscape of breast imaging in neoadjuvant studies and highlight the technological advances in each imaging modality. We then further examine some potential imaging markers for neoadjuvant treatment response in ER+ breast cancers.

Neoadjuvant Therapy for Breast Cancer: Established Concepts and Emerging Strategies

In the last decade, the systemic treatment approach for patients with early breast cancer has partly shifted from adjuvant treatment to neoadjuvant treatment. Systemic treatment administration started as a 'one size fits all' approach but is currently customized according to each breast cancer subtype. Systemic treatment in a neoadjuvant setting is at least as effective as in an adjuvant setting and has several additional advantages. First, it enables response monitoring and provides prognostic information; second, it downstages the tumor, allowing for less extensive surgery, improved cosmetic outcomes, and reduced postoperative complications such as lymphedema; and third, it enables early development of new treatment strategies by using pathological complete remission as a surrogate outcome of event-free and overall survival. In this review we give an overview of the current standard of neoadjuvant systemic treatment strategies for the three main subtypes of breast cancer: hormone receptor-positive, triple-negative, and human epidermal growth factor receptor 2-positive. Additionally, we summarize drugs that are under investigation for use in the neoadjuvant setting.