Long-term outcome in patients with nodal-positive breast cancer treated with sentinel lymph node biopsy alone after neoadjuvant chemotherapy

PURPOSE

Sentinel lymph node biopsy (SLNB) has yet to be accepted as the standard staging procedure in node positive (cN1) breast cancer patients who had clinical complete response in the axilla (cN0) following neoadjuvant chemotherapy (NAC), due to the presumed high false negative rate associated with SLNB in such scenario. This study aimed to determine whether there is a significant difference in the axillary recurrence rate (ARR) and long-term survival in this group of patients, receiving SLNB alone versus axillary lymph node dissection (ALND).

METHODS

A retrospective cohort of cN1 patients who were rendered cN0 by NAC from January 2014 to December 2018 were identified from the Asan Medical Center database. Patients' characteristics and outcomes were collected and analyzed.

RESULTS

902 cN1 patients treated with NAC and turned cN0 were identified. 477 (52.9%) patients achieved complete pathological response in the axilla (ypN0). At a median follow up of 65 months, ARR was 3.2% in the SLNB only group and 1.8% in the ALND group (p = 0.398). DFS and OS were significantly worse in patients with ALND as compared to patients with SLNB only (p = 0.011 and 0.047, respectively). We noted more patients in the ALND group had T3-4 tumor. In the subgroup analysis, we showed that in the T1-2 subgroup (n = 377), there was no statistically significant difference in DFS and OS (p = 0.242 and 0.671, respectively) between SLNB only and ALND group.

CONCLUSION

Our findings suggest that cN1 patients who were converted to ypN0 following NAC may be safely treated with SLNB only.

Encapsulated papillary carcinoma of the breast: An institutional case series and literature review

BACKGROUND

Encapsulated papillary carcinoma of the breast is rare, making difficult diagnosis and resulting in patients undergoing excision biopsy before definitive surgery. Evidence-based guidelines are sparse. We would like to further elucidate the clinicopathological, treatment and survival outcomes.

MATERIALS AND METHODS

54 patients identified, with a median follow up duration of 48 months. Patients' demographics, radiological and clinicopathological characteristics, treatment, adjuvant therapies as well as survival data were analysed.

RESULTS

18 (33.3%) cases were pure EPC, 12 (22.2%) were EPC associated with ductal carcinoma in situ (DCIS) and 24 (44.4%) cases had concurrent invasive ductal carcinoma. EPCs were more likely to present as a solid-cystic mass on sonography (63.8%), regular-shaped (oval or round) (97.9%), lack spiculations (95.7%) and lack suspicious microcalcifications (95.6%). Median tumour size was largest in the EPC with IDC group (18.5 mm). 2 patients developed loco-regional recurrence. Overall survival is good for EPCs of all subtypes.

CONCLUSION

EPC is a rare tumour with excellent prognosis.

Abstract PD15-02: PD15-02 Long Term Outcome in Patients with Nodal-Positive Breast Cancer Treated with Sentinel Lymph Node Biopsy Alone After Neoadjuvant Chemotherapy

Importance: The use of neoadjuvant chemotherapy (NAC) in the clinical care of breast cancer patients has increased considerably over recent years especially in node positive cases. For patients who have axillary nodal metastases prior to NAC, the prevailing standard of care is to undergo an axillary lymph node dissection (ALND), regardless of response to therapy. Sentinel lymph node biopsy (SLNB) has yet to be accepted as the standard staging procedure in patients who had clinical complete response in the axilla following NAC. This is due to the presumed high false negative rate associated with SLNB in such scenario. But there are limited data on the long term outcome of these patients who are only treated with SLNB alone.

Aim: A retrospective cohort study comparing the long term outcome of breast cancer patients with clinically node positive disease (N1) but turned clinically node negative (N0) following NAC, receiving SLNB alone versus ALND.

Methods: Patients who had pathologic proven N1 breast cancer (before NAC) treated with NAC and turned clinically N0 from January 2009 to December 2014 were identified from Asan Medical Center breast cancer database in South Korea. Primary endpoint was axillary recurrence rate (ARR) and secondary endpoints were disease-free survival (DFS) and overall survival (OS). These outcomes were reported for patients who had SLNB alone versus ALND.

Results: 561 patients with clinically stage N1 (cN1) cancer treated with NAC and turned clinically stage N0 (cN0) were identified. 253 (45.1%) patients received SLNB only while 308 (54.9%) patients had ALND. The clinicopathological features of these patients were illustrated in Table 1. Majority of these patients received adjuvant radiotherapy, 81.2% in the SLNB group and 76.5% in the ALND group. In the pathologically stage N0 (ypN0) group, at a median follow up of 69 months, ARR was 3.0% in the SLNB only group and 1.7% in the ALND group (p=0.704). DFS and OS were not significantly different between patients with SLNB alone versus ALND (p= 0.561 and 0.810 respectively). Median number of SLN harvested in the SLNB only group is 5 (range 1 -17). In the pathologically stage N1 (ypN1) group with only 1-2 lymph node positive for metastasis, at a median follow up of 66 months, ARR was 5.8% in the SLNB group and 4.7% in the ALND group (p=0.768). There was no significant difference in DFS and OS between the SLNB and ALND group (p=0.537 and 0.645). In the SLNB only group, the median number of positive lymph node was 1 (range 1-2), the median number of sentinel lymph node was 6 (range 2-18).

Conclusion: In cN1 breast cancer patients who were converted to cN0 following NAC, axillary recurrences were rare. No statistically significant differences were noted in DFS and OS between patients with SLNB or ALND. Our findings suggest that these patients may be safely treated with SLNB only, even when there are up to 2 positive SLNs.

Table 1 Clinicopathological features of breast cancer patients with nodal disease and NAC

Citation Format: Sue Zann Lim, Tae-Kyung Yoo, Sae Byul Lee, Jisun Kim, Il-Yong Chung, Beom Seok Ko, Jong Won Lee, Byung Ho Son, Sei Hyun Ahn, Hee Jeong Kim. PD15-02 Long Term Outcome in Patients with Nodal-Positive Breast Cancer Treated with Sentinel Lymph Node Biopsy Alone After Neoadjuvant Chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD15-02.

Male breast cancer: a Singapore perspective

INTRODUCTION

Male breast cancer (MBC) is rare, representing <1% of all breast cancers. Treatment recommendations have been extrapolated from trial data of female breast cancer patients. This study aims to report our institutional experience of MBC across a 20 year period, analyse the survival outcome and prognosis of this group against female breast cancer patients treated at the same centre.

METHODS

Clinical, histopathological, treatment and survival data of male and female breast cancer patients treated between Jan 1999 and July 2019 at Singapore General Hospital and National Cancer Centre Singapore were identified and analysed.

RESULTS

Fifty-seven male patients were identified. The median age at diagnosis was 63 years. Majority had invasive ductal carcinoma (86%) and presented at an early disease stage: 70.2% presented as Tis/T1/T2 and 49.1% had no axillary nodal involvement. 84.2% had a simple mastectomy with either a sentinel lymph node biopsy or axillary clearance. The median follow up was 5.69 years for males and 5.83 years for females. The median survival was 11.86 years for males and 16.3 years for females. At 5 years, overall survival (OS) was 69.9% (52.3-82.1%) and disease free survival (DFS) was 62.9% (44.9-76.5%) for males compared with OS 83.8% (83.21-84.39%) and DFS 74.5% (73.91-75.09%) for females.

CONCLUSION

MBC remains understudied. Our institutional data indicates that good long term survival in South-East Asian patients can be achieved with treatment protocols that are similar to female breast cancer. More prospective studies are required.

The Impact of Statin Use and Breast Cancer Recurrence - A Retrospective Study in Singapore

Introduction

Statins, HMG-CoA reductase inhibitors, are commonly used cholesterol-lowering medications which are also increasingly recognized to have anti-cancer properties for various cancers, including breast cancer. Most clinical evidence supports a protective effect of statin on reducing breast cancer recurrence, particularly in hormone-receptor positive breast cancers.This study seeks to study the impact of statin use on breast cancer recurrence in an Asian population.

Methods

This is a retrospective study of patients diagnosed with breast cancer at the National Cancer Centre and Singapore General Hospital from 2005-2015. Statin use was defined as use after surgery. Associations between statin use, breast cancer recurrence and overall survival were estimated using Cox proportional hazards regression with adjustment for age, TNM stage, grade, ER/HER2 status, and co-morbidities. Associations between statin-use and disease-specific survival were estimated using competing risks regression.

Results

A total of 7858 females with breast cancer were studied, 1353(17.2%) were statin users, 6505(82.8%) were non-statin users, with a median follow-up of 8.67 years. Distribution of cancer stage, histology, molecular subtypes and grades were similar in both groups. Estrogen receptor(ER) positive (HR 0.57,95%CI 0.43-0.76,p<0.001) and HER2 negative (HR 0.74,95%CI 0.57-0.96,p=0.026) invasive cancers had a lower risk of recurrence in statin users. Statin users trended towards a long term recurrence-risk reduction (all subtypes,HR 0.48,p=0.002; ER-, HR 0.34,p=0.036; HER2+,HR 0.10,p=0.002). The risk-reduction benefit is not appreciated in statin users with DCIS, possibly due to small recurrence event numbers. Disease-specific survival benefit was seen in statin users with ER+ cancers (adjusted SHR 0.71,95%CI 0.53-0.96,p=0.027), especially ER+ invasive cancers (adjusted SHR 0.72, 95%CI 0.53-0.97,p=0.028), but with no statistically significant benefit in overall survival for statin users (all subtypes).

Conclusion

This is the first known retrospective study on the effect of statin use and breast cancer recurrence in an Asian population. Similar to previous international studies, statin use is associated with a risk reduction in breast cancer recurrence. This is especially beneficial in patients who have ER+ and HER2- invasive breast cancer. Statin use is also associated with a reduced risk of breast cancer recurrence in all subtypes of breast cancer in the long term (>6 years post diagnosis).

Atypical Ductal Hyperplasia of the Breast on Core Needle Biopsy: Risk of Malignant Upgrade On Surgical Excision

Purpose

This study identified factors predicting malignant upgrade for atypical ductal hyperplasia (ADH) diagnosed on core-needle biopsy (CNB) and developed a nomogram to facilitate evidence-based decision making.

Methods

This retrospective analysis included women diagnosed with ADH at the National Cancer Centre Singapore (NCCS) in 2010–2015. Cox proportional hazards regression was used to identify clinical, radiological, and histological factors associated with malignant upgrade. A nomogram was constructed using variables with the strongest associations in multivariate analysis. Multivariable logistic regression coefficients were used to estimate the predicted probability of upgrade for each factor combination.

Results

Between 2010 and 2015, 238,122 women underwent mammographic screening under the National Breast Cancer Screening Program. Among 29,564 women recalled, 5,971 CNBs were performed. Of these, 2,876 underwent CNBs at NCCS, with 88 patients (90 lesions) diagnosed with ADH and 26 lesions upgraded to breast malignancy on excision biopsy. In univariate analysis, factors associated with malignant upgrade were the presence of a mass on ultrasound (p = 0.018) or mammography (p = 0.026), microcalcifications (p = 0.047), diffuse microcalcification distribution (p = 0.034), mammographic parenchymal density (p = 0.008). and ≥ 3 separate ADH foci found on biopsy (p = 0.024). Mammographic parenchymal density (hazard ratio [HR], 0.04; 95% confidence interval [CI], 0.005–0.35; p = 0.014), presence of a mass on ultrasound (HR, 10.50; 95% CI, 9.21–25.2; p = 0.010), and number of ADH foci (HR, 1.877; 95% CI, 1.831–1.920; p = 0.002) remained significant in multivariate analysis and were included in the nomogram.

Conclusion

Our model provided good discrimination of breast cancer risk prediction (C-statistic of 0.81; 95% CI, 0.74–0.88) and selected for a subset of women at low risk (2.1%) of malignant upgrade, who may avoid surgical excision following a CNB diagnosis of ADH.

Outcomes of Stage I and II Breast Cancer with Nodal Micrometastases Treated with Mastectomy without Axillary Therapy

PURPOSE

Studies that report equivalent oncologic outcomes of sentinel lymph node biopsy (SLNB) alone versus axillary lymph node dissection (ALND) for T1-2N1mi breast cancers are heavily weighted with patients who received breast-conserving surgery (BCS). The impact of omitting ALND in N1mi patients treated with mastectomy is not well studied. It is also unknown if these patients would benefit from post-mastectomy radiotherapy (PMRT). This study reports the outcomes of patients with T1-2N1mi breast cancer treated by mastectomy without axillary therapy.

METHODS

Patients who had T1-2N1mi breast cancer and underwent mastectomy from January 1998 to December 2018 were identified from our multi-institutional prospective database. Axillary recurrence rate (ARR), disease-free survival (DFS), and overall survival (OS) are reported.

RESULTS

260 patients with pT1-2N1mi breast cancer who had mastectomy were identified. They had either SLNB (35.4%) or ALND (64.6%). Majority of these patients received adjuvant systemic therapy (93.8%). 77 (29.6%) patients received radiotherapy, 31 after SLNB and 46 after ALND. At median follow-up of 61 months, ARR was 1.1% (n = 1) in the SLNB only group, vs. 0.6% (n = 1) in the ALND group (p = 0.752). DFS and OS were not significantly different between patients with SLNB alone versus ALND (p = 0.40 and p = 0.27, respectively). Among 92 patients who had SLNB only, no DFS or OS difference was observed with the use of PMRT.

CONCLUSION

In T1-2N1mi patients with mastectomy and SLNB, axillary recurrences were rare. No statistically significant differences were noted between patients with SLNB, ALND, or PMRT. Our findings suggest that these patients may be safely treated without axillary therapy.

Shaping of the abdominal flap in breast reconstruction: The coning technique in muscle sparing TRAM

In the setting of autologous breast reconstruction, achieving an aesthetic outcome through shaping of the flap is of the upmost importance. We describe the abdominal flap folding technique of ‘coning’ and the indications. We define ‘coning’ as the technique of folding the abdominal flap in a circular fashion to create a conical breast mound, with the line of fusion forming a pillar of tissue for structural integrity. A retrospective study of 34 patients undergoing unilateral muscle-sparing TRAM flap was performed. Of these patients, the majority (79.4%) underwent immediate reconstruction, with the thoracodorsal vessels largely acting as the recipients (94.1%). Three (8.8%) patients were noted to have a contour defect secondary to incomplete folding of the flap. Two (5.9%) patients had partial skin envelope necrosis. One patient had 50% flap loss, requiring return to theatre for excision. In conclusion, coning was used exclusively in the muscle-sparing TRAM flap. This cuff of muscle protected the pedicle during folding through cushioning the perforators at their most vulnerable points. This technique allowed for muscle cuff harvest whilst minimising anterior sheath sacrifice. Coning achieved long-term maintenance of shape, volume and projection.

A Circulating miRNA Signature for Stratification of Breast Lesions among Women with Abnormal Screening Mammograms

Although mammography is the gold standard for breast cancer screening, the high rates of false-positive mammograms remain a concern. Thus, there is an unmet clinical need for a non-invasive and reliable test to differentiate between malignant and benign breast lesions in order to avoid subjecting patients with abnormal mammograms to unnecessary follow-up diagnostic procedures. Serum samples from 116 malignant breast lesions and 64 benign breast lesions were comprehensively profiled for 2,083 microRNAs (miRNAs) using next-generation sequencing. Of the 180 samples profiled, three outliers were removed based on the principal component analysis (PCA), and the remaining samples were divided into training (n = 125) and test (n = 52) sets at a 70:30 ratio for further analysis. In the training set, significantly differentially expressed miRNAs (adjusted p < 0.01) were identified after correcting for multiple testing using a false discovery rate. Subsequently, a predictive classification model using an eight-miRNA signature and a Bayesian logistic regression algorithm was developed. Based on the receiver operating characteristic (ROC) curve analysis in the test set, the model could achieve an area under the curve (AUC) of 0.9542. Together, this study demonstrates the potential use of circulating miRNAs as an adjunct test to stratify breast lesions in patients with abnormal screening mammograms.

Sarcoma of the breast: an update on a rare entity

Breast sarcoma is a rare condition. It consists of a heterogeneous group of non-epithelial tumours arising from the mesenchymal tissue of the breast. It has a distinctly different natural history, treatment response and prognosis as compared with carcinoma of the breast. A different diagnostic approach and treatment strategy have to be defined for this group of tumours. Due to its rarity, the current understanding on breast sarcoma is limited and is mostly based on small retrospective case series or case reports. Hence, the management generally follows the algorithms derived from randomised control trials of soft tissue sarcomas in the extremities and chest wall. Through this review, we discuss the results of major retrospective studies on breast sarcomas including data on epidemiology, aetiology, diagnostic approach, treatment strategies and outcomes of this challenging and potentially aggressive condition.

Abstract P6-08-52: Predicting the likelihood of additional non sentinel lymph node metastasis in early breast cancer: Novel sentinel nodal station status versus Singapore General Hospital nomogram

Background: Sentinel lymph node biopsy (SLNB) has been widely used in early breast cancer patients for the detection of axillary nodal metastasis. We were the first to describe 2 novel sentinel nodal stations (SNS) in relation to the intercostobrachial nerve (ICB) and the medial pectoral neurovascular bundle (MP) at which sentinel lymph nodes (SLN) were consistently identified, even only with the use of blue dye. In a pilot study involving 176 cases, we have shown that the ICB and MP SNS represent sequential echelons of SLN draining the breast. It was observed that the status of the MP SNS can be used in predicting the likelihood of additional non sentinel lymph node metastasis in early breast cancer. Thus, we aim to compare this against the Singapore General Hospital (SGH) nomogram, the existing standard predictive model in the local population. The SGH nomogram was developed from predictors in the Memorial Sloan-Kettering Cancer Centre (MSKCC) nomogram. It uses only 3 pathological parameters: lymphovascular invasion, number of positive and negative SLN. This has been shown to be at least equal if not better than the MSKCC nomogram as a predictive model in the Singapore population.

Methods : All patients who underwent oncologic breast surgery and SLNB (using the SNS identification technique) at the Department of Surgical Oncology, National Cancer Centre Singapore from February 2012 to December 2013 inclusive were reviewed. Patients who fulfilled the following selection criteria were included in the study: [1] invasive ductal or lobular carcinoma, [2] SLN identified in both ICB and MP SNS,[3] axillary clearance done with total lymph nodes ≥ 10, based on a positive SLNB. The performance of the MP SNS status and SGH nomogram in predicting the likelihood of additional non sentinel lymph node metastasis was compared with the calculation of the area under the receiver-operating characteristic curve (AUC).

Results: A total of 49 patients were identified. Majority of the patients had early breast cancers: 94% had tumour size ≤5cm and 71% had N1 disease. The median number of total SLN, ICB and MP nodes identified were 3 (range 2-14), 2 (range 1-7) and 1 (range 1-12) respectively. The median number of positive and negative SLN were both 1 (range 1-5 and 0-9 respectively). The positive predictive value of MP SNS status for additional non sentinel lymph node metastasis was 76.5% (95% CI: 50.1-93.2). The strong association was proven by an odds ratio of 7.15 (95% CI 1.86-27.50, p-value: 0.002). The negative predictive value of MP SNS for eventual N stage was 93.8% (95% CI: 79.2-99.2). In most of the cases, the nodal stage remained at N1 in the presence of negative MP node. The model with MP SNS status yielded an AUC of 0.706 (95% CI: 0.579-0.832) which was higher than that of the SGH nomogram, 0.658 (95% CI: 0.503-0.813).

Conclusions: The novel MP SNS proved to be a single parameter which predicts the likelihood of additional non sentinel lymph nodes metastasis better than the SGH nomogram. More importantly, from the clinical point of view, the MP SNS status can be made available intra-operatively and hence guide the decision for further axillary dissection.

Citation Format: Sue Zann Lim, Puay Hoon Tan, Gay Hui Ho, Preetha Madhukumar, Yirong Sim, Shaun Shi Yan Tan, Cindy Lim, Veronique Kiak Mien Tan, Kong Wee Ong. Predicting the likelihood of additional non sentinel lymph node metastasis in early breast cancer: Novel sentinel nodal station status versus Singapore General Hospital nomogram [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-08-52.

Abstract P2-01-25: Not all sentinel lymph nodes are equal – A predictive model for axillary burden in early breast cancer

Introduction

The Z11 trial demonstrates that an axillary lymph node dissection (ALND) can be avoided in patients with low axillary burden who undergo breast conserving surgery (BCS), combined with whole-breast radiotherapy and systemic therapy. Our group propose a standardisation of sentinel lymph node biopsy (SLNB), incorporating 2 novel sentinel nodal stations (SNS) which represent sequential echelons of SLN draining the breast – the intercostalbrachial nerve (ICB) and the medial pectoral neurovascular bundle (MP). By increasing the specificity and positive predictive value of SLNB, we aim to identify a subgroup of patients who undergo mastectomy who can be spared from ALND and its associated complications.

Materials and Methods

313 female patients who underwent sentinel lymph node biopsy for breast cancer from 2 February 2012 to 19 December 2013 were prospectively studied. 12 patients had bilateral breast cancers, and each laterality was counted as distinct cases, giving a total of 325 cases. 7 had breast surgery performed prior to the SLNB, and the rest had their oncological surgery performed at the same setting of the SLNB. The surgeries were performed by three surgeons in the National Cancer Centre Singapore, using a specific surgical technique to identify SLN at the 2 SNS. Relevant patient demographics, status of SNS and the rates of metastatic non-sentinel lymph nodes were collected and analysed.

Results

A total of 325 SLNBs using the ICB and MP SNS were identified from 169 simple mastectomies, 35 skin sparing mastectomies, and 129 breast conserving surgeries. The median age was 56 (range 27-89). The ICB SLN and MP SLN were identified in 313 (96.3%) and 258 (79.4%) cases respectively. In 249 (76.6%) cases were both ICB and MP nodes identified, of which 55 (16.9%) had metastatic involvement of the SLN.

An axillary clearance was performed if at least one ICB or MP node was positive, and only 27 (49.1%) had further axillary involvement. More than 2 positive SLNs had 100% positive predictive value for further axillary LN metastases. There was a low sensitivity (29.6%) and high false negative rate (70.4%) for positive axillary nodes in patients with ≤2 positive SLNs.

MP nodal status, however, was 85.7% specific (p&lt;0.001) and 48.1% sensitive (p=0.649) and a positive predictive value of 76.5% for axillary nodal involvement. Logistic regression also shows that MP node status is significant for predicting axillary nodal status (OR 5.57, p=0.006).

Conclusion

Our study shows that MP node status is specific, and has a positive predictive value for further axillary LN metastases. Therefore, we propose that in all patients who undergo SLNB with their BCS or mastectomy, an axillary clearance should be performed if the MP node is positive, regardless of the number of positive SLNs.

Citation Format: Yirong Sim, Sue Zann Lim, Shaun S Tan, Alvona Z Loh, Cindy Lim, Preetha Madhukumar, Gay H Ho, Veronique KM Tan, Kong Wee Ong. Not all sentinel lymph nodes are equal – A predictive model for axillary burden in early breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-01-25.

Case Report of an Internal Hernia through a Unilateral Congenital Defect of the Broad Ligament and Literature Review

We report a case of small bowel obstruction resulting from the herniation of small bowel through a unilateral defect in the broad ligament of a woman who had no prior abdominal surgery and was nulliparous. In the absence of previous uterine surgery, delivery trauma and pelvic pathology, congenital abnormality should be considered the cause of the defect in the broad ligament.