Impact of Postmastectomy Radiotherapy on Locoregional Control and Disease-Free Survival in Patients with Breast Cancer Treated with Neoadjuvant Chemotherapy

Does Post-Mastectomy Radiotherapy Confer Survival Benefits on Patients With 1-3 Clinically Positive Lymph Nodes Rendered Pathologically Negative After Neoadjuvant Systemic Chemotherapy: Consensus from A Pooled Analysis?

The advent of taxane-based chemotherapy has revolutionized breast cancer care. This advance has helped improve the response to downstaging tumors that might otherwise be inoperable. It has also helped in rendering clinically (cN+) positive lymph nodes (LNs) pathologically negative (ypN0). The standard of care for cN+ patients included post-mastectomy radiotherapy (PMRT), regardless of the response to neoadjuvant chemotherapy. However, PMRT in patients with 1-3 positive LNs still lacks definitive guidelines. Numerous retrospective results have been inconclusive about the benefit of PMRT on survival in patients with 1-3 positive LNs. This pooled analysis attempts to reach a consensus. The PubMed database was searched through October 2023. The search yielded 27 papers, of which 11 satisfied the inclusion criteria. The locoregional recurrence-free survival (LRRFS), disease-free survival (DFS), and overall survival (OS) for each study were tabulated when given, and two groups were created, the PMRT and NO PMRT, respectively. The results were then pooled for analysis. The total number of patients was 8340, 4136 in the PMRT group, and 4204 in the NO PMRT group, respectively. The LRRFS, DFS, and OS were 96.9%, 82.1%, and 87.3% for the PMRT group and 93.2%, 79.6%, and 84.8% for the NO PMRT group, respectively. There was no statistical significance in LRRFS, DFS, or OS between the two groups (p = 0.61, p = 0.61, and p = 0.38, respectively). PMRT does not seem to confer survival benefits in patients with pN1 rendered ypN0 for stages T1-3. This pooled analysis's findings should be confirmed prospectively with a longer period of follow-up.

Axillary response and outcome in breast cancer patients after neoadjuvant treatment: The role of radiotherapy in reducing recurrence in ypN0 patients with initially cN+ stage

Objective

We aim to explore the clinicopathological features associated with axillary node response and recurrence in breast cancer patients undergoing neoadjuvant treatment (NAT).

Methods

We retrospectively reviewed the medical records of 486 stage I to III breast cancer patients who received NAT and surgery between 2016 and 2021.

Results

A total of 486 cases were reviewed and 154 (31.7%) patients achieved breast pathological complete response (pCR) (ypT0/Tis). Of the 366 cases with initially cN+, 177 (48.4%) cases reach ypN0. Breast pCR is in high accordance to axillary pCR (81.5%). Hormone receptor (HR)-/HER2+ breast cancer patients have the highest axillary pCR rate (78.3%). Patients achieve axillary pCR have a significantly better disease-free survival (DFS) (P=0.0004). Further analysis reveals that the DFS of ypN0 and ypN1 cases are similar (P=0.9049). Moreover, DFS in patients with ypN0 (P<0.0001) and ypN1 (P<0.0001) is significantly better than that in patients with ypN2-3. For post-mastectomy ypN0 cases, radiation could only improve DFS in patients with initially cN+ stage (P=0.0499). Multivariate Cox regression analysis shows that radiation is an independent factor to improve DFS (Hazard ratio (HR): 0.288(0.098-0.841), P=0.0230). Radiation does not improve DFS in pre-cN0/ypN0 patients (P=0.1696).

Conclusion

Axillary pCR rate is higher than breast pCR rate. HR-/HER2+ patients have the highest axillary pCR rate. Axillary pCR is associated with better DFS. Radiation could further improve DFS in ypN0 patients with initially positive nodal disease.

Postmastectomy Radiotherapy After Neoadjuvant Chemotherapy in cT1-2N+ Breast Cancer Patients: A Single Center Experience and Review of Current Literature

Purpose

Postmastectomy radiotherapy (PMRT) after neoadjuvant chemotherapy (NAC) in breast cancer patients with initial clinical stage cT1-2N+, especially for those who achieved ypT1-2N0, is still controversial. This study was to evaluate the survival prognosis of cT1-2N+ patients after NAC with or without PMRT, and to discuss the selection of patients who may omit PMRT.

Patients and Methods

From January 2005 to December 2017, 3055 female breast cancer patients underwent mastectomy in our medical center, among whom 215 patients of cT1-2N+ stage, receiving NAC with or without PMRT were finally analyzed. The median follow-up duration was 72.6 months. The primary endpoint was disease-free survival (DFS), and secondary endpoint was overall survival (OS). Comparison was conducted between PMRT and non-PMRT subgroups.

Results

Of the 215 eligible patients, 35.8% (77/215) cT1-2N+ patients achieved ypT0-2N0 after NAC while 64.2% (138/215) of the patients remained nodal positive (ypT0-2N+). The 5-year DFS of ypT0-2N0 non-PMRT was 79.5% (95% confidence interval [CI] 63.4-95.6%). No statistically significant difference was observed between the ypT0-2N0 PMRT and non-PMRT subgroups for the 5-year DFS (78.5% vs 79.5%, p = 0.673) and OS (88.8% vs 90.8%, p = 0.721). The 5-years DFS didn't obviously differ between the ypT0-2N0 non-PMRT subgroup and cT1-2N0 subgroup (79.5% vs 93.3%, p = 0.070). By using Cox regression model in multivariate analyses of prognosis in ypT0-2N+ PMRT subgroup, HER2 overexpression and triple-negative breast cancer were significantly poor predictors of DFS and OS, while ypN stage was significant independent predictors of OS.

Conclusion

An effective response to NAC (ypT0-2N0) indicates a sufficiently favorable prognosis, and PMRT might be omitted for cT1-2N+ breast cancer patients with ypT0-2N0 after NAC.

Metastasis prevention: targeting causes and roots

The spread of tumor cells from the primary focus, metastasis, is the main cause of cancer mortality. Therefore, anticancer therapy should be focused on the prevention of metastatic disease. Key targets can be conditions in the primary tumor that are favorable for the appearance of metastatic cells and the first steps of the metastatic cascade. Here, we discuss different approaches for targeting metastasis causes (hypoxia, metabolism changes, and tumor microenvironment) and roots (angiogenesis, epithelial-mesenchymal transition, migration, and invasion). Also, we emphasize the challenges of the existing approaches for metastasis prevention and suggest opportunities to overcome them. In conclusion, we highlight the importance of clinical evaluation of the agents showing antimetastatic effects in vivo, especially in patients with early-stage cancers, the identification of metastatic seeds, and the development of therapeutics for their eradication.