Predicting breast and axillary response after neoadjuvant treatment for breast cancer: The role of histology vs receptor status

Residual Axillary Metastases in Node-Positive Breast Cancer Patients After Neoadjuvant Treatment: A Register-Based Study

BACKGROUND

Lymph node (LN) metastasis after neoadjuvant chemotherapy (NACT) generally warrants axillary lymph node dissection, which opposes guidelines of upfront surgery in many cases. We investigated the risk of having additional metastases in the axilla when the LNs removed by targeted axillary dissection (TAD) harbored metastases after NACT. We aimed to identify subgroups suitable for de-escalated axillary treatment.

METHODS

This register-based study used data from the Danish Breast Cancer Cooperative Group database. Data were analyzed with logistic regression models. The primary outcome was the metastatic burden in non-TAD LNs in patients with positive TAD LNs after NACT.

RESULTS

Among 383 patients, < 66.6% positive TAD LNs (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.17-0.62), only isolated tumor cells (ITCs) [OR 0.11, 95% CI < 0.01-0.82], and breast pathological complete response (pCR) [OR 0.07, 95% CI < 0.01-0.56] were associated with a low risk of having more than three positive non-TAD LNs. In 315 patients with fewer than three positive non-TAD LNs, the proportion of positive TAD LNs (OR 0.45, 95% CI 0.27-0.76 for 33.3-66.6% vs. > 66.6%), size of the TAD LN metastasis (OR 0.14, 95% CI 0.04-0.54 for ITC vs. macrometastasis), tumor size at diagnosis (OR 0.30, 95% CI 0.15-0.64 for 20-49 mm vs. ≥ 50 mm) and breast pCR (OR 0.38, 95% CI 0.15-0.96) were associated with residual LN metastases in the axilla.

CONCLUSIONS

Breast pCR or ITC only in TAD LNs can, with reasonable certainty, preclude more than three positive non-TAD LNs. Additionally, patients with only ITCs in the TAD LN had a low risk of having any non-TAD LN metastases after NACT. De-escalated axillary treatment may be considered in both subgroups.

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&lt;0.0001) and ypN1 (P&lt;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.

Differences in sensitivity to neoadjuvant chemotherapy among invasive lobular and ductal carcinoma of the breast and implications on surgery-A systematic review and meta-analysis

Meta-analysis of >87,000 patients demonstrates that patients with invasive lobular carcinoma of the breast are far less likely to achieve pCR of the breast or axilla compared to their ductal counterparts, receive less BCS and more frequently return positive margins.

BACKGROUND

Neoadjuvant chemotherapy (NACT) facilitates tumour downstaging, increases breast conserving surgery (BCS) and assesses tumour chemosensitivity. Despite clinicopathological differences in Invasive Ductal Carcinoma (IDC) and Invasive Lobular Carcinoma (ILC), decision making surrounding the use NACT does not take account of histological differences.

AIM

To determine the impact NACT on pathological complete response (pCR), breast conserving surgery (BCS), margin status and axillary pCR in ILC and IDC.

METHODS

A systematic review was performed in accordance with the PRISMA guidelines. Studies reporting outcomes among ILC and IDCs following NACT were identified. Dichotomous variables were pooled as odds ratios (ORs) with 95% confidence intervals_(CI) using the Mantel-Haenszel method. P-values <0.05 were statistically significant.

RESULTS

40 studies including 87,303 (7596 ILC [8.7%]and 79,708 IDC [91.3%]) patients were available for analysis. Mean age at diagnosis was 54.9 vs. 50.9 years for ILC and IDC, respectively. IDCs were significantly more likely to achieve pCR (22.1% v 7.4%, OR: 3.03 [95% CI 2.5-3.68] p < 0.00001), axillary pCR (23.6% vs. 13.4%, OR: 2.01 [95% CI 1.77-2.28] p < 0.00001) and receive BCS (45.7% vs. 33.3%, OR 2.14 [95% CI 1.87-2.45] p < 0.00001) versus ILCs. ILCs were significantly more likely to have positive margins at the time of surgery (36% vs 13.5%, OR 4.84 [95% CI 2.88-8.15] p < 0.00001).

CONCLUSION

This is the largest study comparing the impact of NACT among ILC and IDC with respect to pCR and BCS. ILC has different outcomes to IDC following NACT and incorporate it into treatment decisions and future clinical guidelines.

Relationship Between Breast and Axillary Pathologic Complete Response in Women Receiving Neoadjuvant Chemotherapy for Breast Cancer

OBJECTIVE

We aim to delineate the relationship between breast and axillary pathologic complete response (pCR) in patients receiving neoadjuvant chemotherapy for breast cancer.

METHODS

We performed a retrospective cohort study of patients with clinical T1-4N0-3M0 breast cancer receiving neoadjuvant chemotherapy followed by surgical therapy at Sunnybrook Health Sciences Centre in Toronto, Canada between 2014 and 2019. Clinicopathologic data were abstracted from the electronic medical record. Women were stratified into receptor subtypes as follows: hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-), HR+/HER2+, HR-/HER2+ and HR-/HER2- (triple negative) and compared with Fisher's exact test. Our primary outcome was to assess the positive predictive value of breast pCR for determining axillary pCR, and vice versa.

RESULTS

There were 374 breast cancers, with 109 (29.1%) achieving breast pCR (ypT0/Tis). Amongst node-positive tumours achieving breast pCR, rates of associated axillary pCR (ypN0/0i+) were as follows: HR+/HER2- (2/6, 33.3%), HR+/HER2+ (12/13, 92.3%), HR-/HER2+ (15/17, 88.2%) and triple negative (15/17, 88.2%) (P = 0.02). Conversely, amongst node-positive tumours achieving axillary pCR, rates of associated breast pCR were: HR+/HER2- (2/10, 20.0%), HR+/HER2+ (12/23, 52.2%), HR-/HER2+ (15/24, 62.5%) and triple negative (15/26, 57.7%) (P = 0.1).

CONCLUSIONS

Breast pCR is a strong predictor of axillary pCR in women with HER2-positive and triple-negative breast cancers. Conversely, axillary pCR is a modest predictor of breast pCR for these subtypes. There is a poor relationship between breast and axillary pCR in women with hormone receptor-positive disease. These data may inform future de-escalation of surgery in women with HER2-positive and triple-negative disease.

Response in breast vs axilla after neoadjuvant treatment and implications for nonoperative management of invasive breast cancer

Improved imaging and neoadjuvant chemotherapy (NAT) have led to higher pathologic complete response rates (pCR) in patients with invasive breast cancer. This has questioned the necessity of surgery and axillary lymph node (ALN) dissection in these patients. Prospective clinical trials are implementing extensive core biopsies of the tumor bed of patients with clinical complete response as a means to identify and spare them breast surgery. In addition, it is anticipated that patients with pCR are most likely going to have no or minimal disease in ALN as well. To verify the feasibility of these trials, we performed a pathologic analysis of all our patients who have undergone NAT from 2009 to present. Using pathology data base, we identified 362 patients treated with neoadjuvant chemotherapy followed by surgery. Clinical and pathologic information including gross and microscopic descriptions as well as biomarker status was collected. pCR was 50% for patients with negative ALN pretreatment but only 28% for patients with positive ALN at diagnosis. Despite achieving pCR in the breast, up to 10% of patients with positive ALN and 1% with negative ALN had persistent disease. Eight percent of patients that were presumed to have no ALN disease either clinically and or by imaging were found to have metastatic carcinoma in ALN. The metastases were predominantly (80%) <5 mm, and not palpable on physical examination and or due to biopsy sampling error. pCR in breast and ALN directly correlated with tumor size, ALN disease, and Her2 positive and triple negative receptor phenotype. In breast cancer patients who are node positive at time of diagnosis with pCR in the breast after neoadjuvant chemotherapy, residual lymph node disease was very uncommon. Further study is warranted to select patients who may avoid breast and axillary surgery post neoadjuvant chemotherapy.