Are there patients with T1 to T2, lymph node-negative breast cancer who are "high-risk" for locoregional disease recurrence?

The optimal regional irradiation volume for breast cancer patients: A comprehensive systematic review and network meta-analysis of published studies

Background

Currently, the optimal adjuvant regional nodal irradiation (RNI) volume for breast cancer (BC) remained controversial. We aimed to define the optimal RNI treatment volume for BC by using a comprehensive network meta-analysis (NMA) of published studies.

Materials and methods

PubMed, Embase, Medline, and Cochrane Central Register of Controlled Trials were searched from database inception to 30 May 2022. Studies assessing different adjuvant RNI volumes for BC were eligible for inclusion. The primary outcome was overall survival (OS), and secondary outcome was disease-free survival (DFS) and distant-metastasis-free survival (DMFS).

Results

A total of 29,640 BC patients from twenty studies were included. The pooled hazard ratio demonstrated that internal mammary node irradiation (IMNI) in BC patients significantly improved OS giving HR (hazard ratio) of 0.87 (95%CI: 0.83-0.91, p<0.001), DFS with HR of 0.78 (95%CI: 0.68-0.90, p<0.01), and DMFS with HR of 0.87 (95%CI: 0.79-0.97, p<0.01) when compared to controls. Sub-group analysis indicated that RNI with IMNI significantly improved OS (HR 0.87, 95%CI: 0.81-0.93, p<0.01), DFS (HR 0.65, 95%CI: 0.56-0.77, p<0.01), and DMFS (HR 0.90, 95%CI: 0.82-0.98, p=0.02) when compared to RNI without IMNI. NMA showed that CW/WB (chest wall/whole breast) + RNI with IMNI significantly improved DFS (HR 0.93, 95%CI: 0.86-1.00) and DMFS (HR 0.90, 95%CI: 0.81-0.99), but not for OS (HR 0.93, 95%CI: 0.84-1.03) when compared to CW/WB alone. Based on the analysis of the treatment ranking, CW/WB+RNI with IMNI appeared as the best treatment approach for BC patients.

Conclusions

Our pooled results demonstrated that RNI with IMNI yielded a significant survival advantage for BC patients. NMA showed that CW/WB+RNI with IMNI was the optimal radiation volume for BC patients.

IMNI PRECISION trial protocol: a phase II, open-label, non-inferior randomized controlled trial of tailoring omission of internal mammary node irradiation for early-stage breast cancer

BACKGROUND

Since the publication of MA-20 and EORTC-22922 trials, chest wall (CW)/ whole breast (WB) irradiation + comprehensive regional nodal irradiation (RNI) with internal mammary node irradiation (IMNI) has been the standard adjuvant treatment for early-stage breast cancer (BC). However, one size does not fit all BC, and the risk of recurrence significantly varies among this patient population. In addition, whether all BC patients presented with one to three positive lymph nodes (pN1) could benefit from IMNI remains controversial. Thus, the optimal adjuvant RNI volume for early-stage BC with T1-2N1 remains undetermined.

METHODS

The IMNI PRECISION trial is a single institute, open-labeled, non-inferior, randomized controlled trial. A total of 214 clinically "high risk" BC patients which is characterized as having at least two of the five clinically adverse factors (age ≤ 40, three positive LN, T2 stage, grade 3 and Ki-67 index ≥ 14%), but genomic score "low risk" (the genomic score ≤ 44) N1 breast cancers are randomly assigned to omitting IMNI group (experimental group) or with IMNI (control group) with a 1:1 ratio. The primary endpoint of this trial is event-free survival, and secondary endpoints include overall survival and locoregional recurrence-free survival.

DISCUSSION

The IMNI PRECISION design allows promising clinical-genomic model to stratify the individualized risk of developing recurrence and guides the optimal RNI treatment for early-stage (pT1-2N1) BC patients. We anticipate that our results would provide high-level evidence to tailor IMNI according to individualized recurrence risk of BC.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04517266 . Date of registration: August 18, 2020. Status: Recruiting.

Survival outcomes after breast-conserving surgery plus radiotherapy compared with mastectomy in breast ductal carcinoma in situ with microinvasion

Ductal carcinoma in situ with microinvasion (DCIS-MI) is a subtype of breast cancer with a good prognosis, for which both breast conserving surgery plus radiotherapy (BCS + RT) and mastectomy are feasible surgical methods, but no clear conclusion has been made on the choice of these treatments. We used the Surveillance, Epidemiology and End Results database to extract 5432 DCIS-MI patients. Participants were divided into the BCS + RT group and the mastectomy group. We compared the overall survival (OS) and breast cancer-specific survival (BCSS) of the two groups using the Kaplan-Meier method and Cox regressions before and after propensity score matching (PSM). Before PSM, both univariate and multivariate analyses showed that BCS + RT group had significantly higher OS and BCSS compared with patients in the mastectomy group (P < 0.001). After PSM, the multivariate analysis showed that compared with mastectomy, the BCS + RT showed significantly higher OS and BCSS (HR = 0.676, 95% CI = 0.540-0.847, P < 0.001; HR = 0.565,95% CI = 0.354-0.903, P = 0.017). In addition, the subgroup analysis showed that BCS + RT is at least equivalent to mastectomy with respect to OS and BCSS in any subgroup. For patients with DCIS-MI, the prognosis of BCS + RT was superior to mastectomy.

The effect of postmastectomy radiation therapy on high-risk patients with T1-2N0 breast cancer

BACKGROUND

The prognostic impact of postmastectomy radiation therapy (PMRT) on high-risk patients with T1-2N0 breast cancer is controversial. We aimed to investigate the effect of PMRT on high-risk patients with T1-2N0 breast cancer.

METHODS

A total of 3439 patients diagnosed with T1-2N0 breast cancer who received mastectomy between 2000 and 2016 in our institute were retrospectively analyzed. Leveraging the Fine and Gray competing risks regression in unirradiated patients, risk factors of locoregional recurrence (LRR) were identified. All patients were stratified into high-risk (3 or 4 risk factors) and low-risk (no more than 2 risk factors) groups. The prognostic effect of PMRT was estimated in two subgroups. This subgroup analysis was also performed in patients with T2N0 breast cancer.

RESULTS

The median follow-up was 89 months. The 5-year cumulative incidence of LRR was 2.2% in unirradiated patients. Tumor size, estrogen receptor (ER) status, histologic grade and lymphovascular invasion (LVI) were identified as independent risk factors of LRR. In the high-risk group, PMRT was correlated with a 8.3% risk reduction of 5-year LRR, 7.8% risk reduction of 5-year distant recurrence (DR), and 6.4% risk reduction of 5-year breast cancer mortality (BCM), whereas it was not correlated with LRR, DR, or BCM in low-risk group. In patients with T2N0 breast cancer, PMRT was associated with decreased LRR, DR and BCM in high-risk group, other than low-risk group.

CONCLUSIONS

PMRT presented heterogenous effect on patients with T1-2N0 breast cancer. Patients at high risk of LRR were more likely to benefit from PMRT.

What Is High-risk Breast Cancer With Pathologically Negative Lymph Nodes for Regional Recurrence?

PURPOSE

This study aimed to identify high-risk factors for regional recurrence in patients with breast cancer with pathologically negative lymph nodes.

METHODS AND MATERIALS

We retrospectively analyzed 3800 patients with stage pT1-pT3 breast cancer and pathologically negative lymph nodes between 2004 and 2012. All patients underwent upfront surgery with curative intent. Adjuvant systemic treatments were administered to most patients (96.7%) based on contemporary guidelines.

RESULTS

After a median follow-up of 83 months (range, 7-175 months), the estimated 10-year cumulative incidence rate of regional recurrence was 2.0%. Multivariate competing risk analysis revealed that high histologic grade, positive lymphovascular invasion, and stage pT2-3 were significant risk factors for any regional recurrence. Patients with ≥2 risk factors showed a significantly higher 10-year cumulative incidence rate of any regional recurrence than those with 1 or no risk factors (5.5% vs 1.2%; P < .001). When the number of retrieved lymph nodes was less than 10, the difference in the incidence rate of regional recurrence between patients with ≥2 risk factors and those with 1 or no risk factors was greater (6.6% vs 1.3%, respectively; P < .001). The 10-year disease-free survival was worse in patients with ≥2 risk factors than in those with 1 or no risk factors (84.7% vs 90.0%, respectively; P < .001). Patients with ≥2 risk factors also showed worse 10-year overall survival than did those with 1 or no risk factors (91.3% vs 97.0%, respectively; P < .001).

CONCLUSIONS

Overall, the cumulative incidence rate of any regional recurrence was low at 10 years. However, patients with ≥2 risk factors showed an increased risk of any regional recurrence and worse disease-free survival, particularly when the number of retrieved lymph nodes was less than 10.

Mastectomy alone for pT1-2 pN0-1 breast cancer patients: when postmastectomy radiotherapy is indicated

PURPOSE

To assess outcome of breast cancer (BC) stages pT1-2 N0-1 after mastectomy alone and to identify prognostic factors calling for the need of postmastectomy radiotherapy.

METHODS

Patients who were not eligible for breast conserving surgery (BCS) were operated on with mastectomy between 1998 and 2008. Locoregional (LRR), distant (DM) control and breast cancer specific survival (BCSS) were retrospectively evaluated. Cumulative incidence (CI) of events was estimated according to Kalbfleisch and Prentice while Gray's test tested difference. Kaplan-Meier method for survival and Cox proportional hazards model for univariable and multivariable analysis were used. A matched pair analysis between mastectomy alone and BCS plus whole breast irradiation (WBI), using the propensity score method, was performed.

RESULTS

1281 pT1-2 N0 and 1081 pT1-2 N1 were identified. Median follow-up was 8.2 years (9.2 years for survival). Overall, LRR rate was low for both N0 and N1 subgroups (10-year CI, 8.8% and 10.9%, respectively). Young age, lymphovascular invasion and Ki-67 ≥ 20% were proved to be statistically significant prognostic factors at multivariable analysis. The combination of ≥ 2 risk factors increased LRR rate to ≥ 15%. Risk factors combination weighed on LRR rate more than nodal status itself. DM rate doubled moving from negative to positive nodal status (10-year CI 10.5% versus 20.3%, respectively). BCSS remained high in both N0 and N1 subgroups (10-year CI 92.4% versus 84.5%, respectively). Remarkably, all the molecular subtypes except Luminal A significantly affected DM and BCSS both in the N0 and N1 subgroups. Nodes number significantly impacted on DM and BCSS but not on locoregional control. In the matched pair analysis, WBI decreased nodal recurrence rate and improved distant control, without affecting survival.

CONCLUSIONS

Selected patients, namely those with at least two additional risk factors, presented high enough LRR risk to support the use of postmastectomy radiotherapy in both N0 and N1 subgroups. Moreover, the observation that radiotherapy may provide benefits that go beyond local control deserves to be further investigated.

Established and Validated Novel Nomogram for Predicting Prognosis of Post-Mastectomy pN0-1 Breast Cancer without Adjuvant Radiotherapy

Aim

To establish and validate a nomogram for predicting prognosis of breast cancer patients with pN0-1 who were treated with mastectomy and without adjuvant radiotherapy.

Material and Methods

The LASSO regression was performed to identify predictors of breast cancer-specific survival (BCSS), local regional recurrence (LRR) and distant metastasis (DM). Model performance was evaluated by the concordance index (C-index) and calibration plot.

Results

The 5-year BCSS, LRR and DM rates for the entire cohort were 98%, 2% and 4%, respectively. LASSO regression analysis found that pathological T stage, number of positive LN, grade and Ki-67 were significant predictors for both BCSS and DM-free survival, while number of resected LN and PR status were predictors for DM-free survival. In addition, number of positive LN was the only significant predictor for developing LRR. The C-indexes for the 5-year BCSS and DM nomograms were 0.81 and 0.78 in the training data set, 0.65 and 0.70 in the testing set and 0.72 and 0.69 in the external validation set, respectively.

Conclusion

Our prognostic nomograms accurately predict 5-year BCSS and DM-free survival in post-mastectomy breast cancer without adjuvant radiotherapy, which provides a useful tool to identify high-risk patients who could benefit from additional adjuvant therapy.

Clinical characteristics of breast ductal carcinoma in situ with microinvasion: a narrative review

Ductal carcinoma in situ (DCIS) with microinvasion (DCIS-MI) is defined as the extension of cancer cells beyond the basement membrane into adjacent tissue with no focus larger than 1 mm or a maximum diameter of less than 1 mm for multiple invasive foci. DCIS-MI constitutes approximately 1% of all breast cancer cases and 5% to 10% of cases of DCIS. The current literature is controversial concerning the clinical prognostic features and management of DCIS-MI. This narrative review described recently reported literature regarding the characteristics, diagnosis, treatment, and prognosis of DCIS-MI.

Can a subgroup at high risk for LRR be identified from T1-2 breast cancer with negative lymph nodes after mastectomy? A meta-analysis

Purpose: To identify a subgroup at high risk for loco-regional recurrence (LRR) from T1-2 breast cancer with negative lymph nodes (N0) after mastectomy by using a meta-analysis.Methods and materials: Published studies on the relationship between clinical features and LRR of breast cancer were identified from public databases, including PubMed, EMBASE, and the Cochrane Library. High-risk features for LRR in this patient population were defined based on the pooled results of meta-analysis.Results: For the meta-analysis, a total of 11244 breast cancers with pT1-2N0 after mastectomy from 20 publications were included for analysis. The pooled results indicated that age (hazard ratio (HR) 1.77, P=0.001), lymphovascular invasion (LVI) (HR 2.23, P<0.001), histologic grade (HR 1.66, P<0.001), HER2 status (HR 1.65, P=0.027), menopausal status (HR 1.36, P=0.015), and surgical margins (HR 2.56, P=0.014) were associated with a significantly increased risk of developing LRR in this patient population group, but not for tumor size (HR 1.32, P=0.23), systematic therapy (HR 1.67, P=0.20), and hormonal receptor status (HR 1.04, P=0.73).Conclusion: In the current study, patients with young age, positive LVI, high histologic grade, HER-2 positive, premenopausal, and positive surgical margins have an increased risk of developing LRR. Further prospective trials are needed to clearly define the role of adjuvant postmastectomy radiotherapy in T1-2N0 breast cancer at high risk of developing LRR.

Is post-mastectomy radiation therapy contributive in pN0-1mi breast cancer patients? Results of a French multi-centric cohort

AIM

To assess the value of post-mastectomy radiation therapy (PMRT) to breast cancer (BC) patients with no or minimal lymph node (LN) involvement.

MATERIALS AND METHODS

We retrospectively analysed a French multi-centric cohort of 4283 patients treated by mastectomy and axillary dissection, with or without PMRT, between 1980 and 2013. Practices were analysed for three treatment periods (1980-1999, 2000-2005 and 2006-2013). The impact of PMRT on loco-regional recurrence (LRR), disease-free survival (DFS), BC-specific survival and overall survival was assessed in pN0-1mi patients using multivariate analyses (logistic regression and Cox model). It was subsequently assessed based on the number of clinicopathological recurrence-risk factors, generating a prognostic index (French-PMRT index), to isolate a pN0-1mi patients subgroup that might derive a benefit from PMRT. We tested the accuracy of the Cambridge-PMRT (c-PMRT) index to discriminate between patients with significantly different outcomes and the value of PMRT in each c-PMRT prognostic group.

RESULTS

More than half of the pN0-1mi patients of our cohort underwent PMRT, which almost significantly improved LRR-free survival and DFS. Matching pN0-1mi patients based on the number of clinicopathologic recurrence-risk factors identified a higher risk subpopulation (≥3 recurrence-risk factors), but PMRT did not improve patient outcomes. Although the c-PMRT index had the potential to predict patient outcomes, its use did not help in making the decision of whether or not to use PMRT.

CONCLUSION

We failed to isolate a subgroup of early BC patients without LN involvement suitable for PMRT, despite studying a large cohort.

Axillary Micrometastases and Isolated Tumor Cells Are Not an Indication for Post-mastectomy Radiotherapy in Stage 1 and 2 Breast Cancer

BACKGROUND

Randomized trials demonstrate equivalent locoregional control with sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) for T1-2 micrometastatic breast cancer, but include few mastectomy patients. Consensus is lacking on indications for post-mastectomy radiotherapy (PMRT) in this population. Herein, we evaluate locoregional recurrence (LRR) in an unselected, modern cohort of T1-2 breast cancer patients with micrometastases or isolated tumor cells (ITCs; N0i+/N1mi) having a mastectomy.

METHODS

We identified patients with T1-2N0i+/N1mi breast cancer treated with mastectomy from January 2006 to December 2011. Recurrent, bilateral, and neoadjuvant cases were excluded. The primary outcome of interest was LRR.

RESULTS

Overall, 352 patients [211 (60%) with ITCs and 141 (40%) with micrometastases] were identified. 162 (46%) patients had SLNB alone and one node was positive in 295 (84%) cases; 31 (9%) patients had PMRT and 95% had systemic therapy. At a median 6 years of follow-up, the overall crude LRR rate was 2.8% (n = 9), with no axillary recurrences, and the crude LRR rate was 3.9% among those who had SNB alone. Those with LRR had a median age of 55 years, median tumor size of 1.7 cm, and ductal histology; the majority were high-grade (89%) and estrogen receptor positive (78%), with one positive node (89%). There was no association between LRR and receipt of PMRT (p = 0.4), SLNB versus ALND (p = 0.2), or number of positive nodes (p = 0.7) using the log-rank test.

CONCLUSIONS

LRR was infrequent among T1-2N0i+/N1mi patients treated with mastectomy without PMRT, with no axillary failures, suggesting that PMRT or nodal radiotherapy are not routinely indicated in this population.