Oncologic Safety of Immediate Oncoplastic Surgery Compared with Standard Breast-Conserving Surgery for Patients with Invasive Lobular Carcinoma

BACKGROUND

Invasive lobular carcinoma (ILC) of the breast grows in a diffuse pattern, resulting in a high risk of positive margins at surgical resection. Oncoplastic approaches have been shown to reduce this risk, but concerns persist around the safety of immediate oncoplastic surgery for those with ILC. This study evaluated the short- and long-term oncologic outcomes of immediate oncoplastic surgery for patients with ILC.

METHODS

This study retrospectively analyzed an institutional database of stages I to III ILC patients who underwent breast-conserving surgery (BCS) with or without immediate oncoplastic surgery (oncoplastic closure or oncoplastic reduction mammoplasty [ORM]). The study compared positive margin rates, rates of successful BCS, and recurrence-free survival (RFS) by type of surgery.

RESULTS

For 494 patients the findings showed that the use of immediate ORM was associated with significantly lower odds of positive margins (odds ratio [OR], 0.34; 95 % confidence interval [CI], 0.17-0.66; p = 0.002). Both lumpectomy with oncoplastic closure and ORM were significantly associated with higher rates of successful BCS than standard lumpectomy (94.2 %, 87.8 %, and 73.9 %, respectively; p < 0.001). No difference in RFS was observed between those undergoing immediate oncoplastic surgery and those undergoing standard lumpectomy alone.

CONCLUSIONS

The patients with stages I to III ILC who underwent immediate oncoplastic surgery had significant benefits including lower odds of positive margins and higher rates of successful BCS, with both types of immediate oncoplastic surgery showing similar RFS compared with lumpectomy alone. This supports the oncologic safety of immediate oncoplastic surgery for diffusely growing tumors such as ILC, providing it an ideal option for patients desiring BCS.

Circulating tumor cells in early lobular versus ductal breast cancer and their associations with prognosis

This is a secondary data analysis of the TIPPING study, which included 1,121 patients with stage I-III breast cancer who had enumeration of CTCs (by either CellSearch or immunomagnetic enrichment and flow cytometry [IE/FC]) and disseminated tumor cells (DTCs) at the time of surgical resection between 1999 and 2012. The primary endpoint was mean number of CTCs by histology, taking into account method of detection and treatment type, and evaluation of histology specific prognostic cutpoints. Overall, patients with ILC had significantly higher CTC counts than those with IDC, a finding which persisted in the 382 patients with CTC enumeration by IE/FC method. Additionally, among those with primary surgery, patients with ILC had significantly higher mean CTC counts than those with IDC (mean 2.11 CTCs/mL versus 0.71 CTCs/mL respectively, p < 0.001), which persisted on multivariate analysis. Patients with ILC and CTC-high/DTC-high status trended towards reduced DRFS HR = 9.27, 95% CI 0.95-90.5, p = 0.055) and had significantly decreased BCSS (HR = 10.4, 95% CI 1.07-99.7, P = 0.043) compared with those who were CTC-low/DTC-low. In the IDC group, CTC-high/DTC-high status was not associated with either DRFS or BCSS. In neoadjvuantly treated patients, there was no significant difference in CTC counts in the ILC group versus the IDC group (mean 0.89 CTCs/mL versus 1.06 CTCs/mL respectively, p = 0.82). Our findings contribute to the limited literature on CTCs and DTCs in ILC, and suggest that clinical utility and optimal thresholds for CTC and DTC assays may differ by histologic subtype in early-stage breast cancer.

Clinicopathologic and genetic analysis of invasive breast carcinomas in women with germline CHEK2 variants

PURPOSE

Germline pathogenic variants in checkpoint kinase 2 (CHEK2) are associated with a moderately increased risk of breast cancer (BC). The spectrum of clinicopathologic features and genetics of these tumors has not been fully established.

METHODS

We characterized the histopathologic and clinicopathologic features of 44 CHEK2-associated BCs from 35 women, and assessed responses to neoadjuvant chemotherapy. A subset of cases (n = 23) was additionally analyzed using targeted next-generation DNA sequencing (NGS).

RESULTS

Most (94%, 33/35) patients were heterozygous carriers for germline CHEK2 variants, and 40% had the c.1100delC allele. Two patients were homozygous, and five had additional germline pathogenic variants in ATM (2), PALB2 (1), RAD50 (1), or MUTYH (1). CHEK2-associated BCs occurred in younger women (median age 45 years, range 25-75) and were often multifocal (20%) or bilateral (11%). Most (86%, 38/44) were invasive ductal carcinomas of no special type (IDC-NST). Almost all (95%, 41/43) BCs were ER + (79% ER + HER2-, 16% ER + HER2 + , 5% ER-HER2 +), and most (69%) were luminal B. Nottingham grade, proliferation index, and results of multiparametric molecular testing were heterogeneous. Biallelic CHEK2 alteration with loss of heterozygosity was identified in most BCs (57%, 13/23) by NGS. Additional recurrent alterations included GATA3 (26%), PIK3CA (226%), CCND1 (22%), FGFR1 (22%), ERBB2 (17%), ZNF703 (17%), TP53 (9%), and PPM1D (9%), among others. Responses to neoadjuvant chemotherapy were variable, but few patients (21%, 3/14) achieved pathologic complete response. Most patients (85%) were without evidence of disease at time of study (n = 34). Five patients (15%) developed distant metastasis, and one (3%) died (mean follow-up 50 months).

CONCLUSION

Almost all CHEK2-associated BCs were ER + IDC-NST, with most classified as luminal B with or without HER2 overexpression. NGS supported the luminal-like phenotype and confirmed CHEK2 as an oncogenic driver in the majority of cases. Responses to neoadjuvant chemotherapy were variable but mostly incomplete.

Mechanosensitive hormone signaling promotes mammary progenitor expansion and breast cancer risk

Tissue stem-progenitor cell frequency has been implicated in tumor risk and progression, but tissue-specific factors linking these associations remain ill-defined. We observed that stiff breast tissue from women with high mammographic density, who exhibit increased lifetime risk for breast cancer, associates with abundant stem-progenitor epithelial cells. Using genetically engineered mouse models of elevated integrin mechanosignaling and collagen density, syngeneic manipulations, and spheroid models, we determined that a stiff matrix and high mechanosignaling increase mammary epithelial stem-progenitor cell frequency and enhance tumor initiation in vivo. Augmented tissue mechanics expand stemness by potentiating extracellular signal-related kinase (ERK) activity to foster progesterone receptor-dependent RANK signaling. Consistently, we detected elevated phosphorylated ERK and progesterone receptors and increased levels of RANK signaling in stiff breast tissue from women with high mammographic density. The findings link fibrosis and mechanosignaling to stem-progenitor cell frequency and breast cancer risk and causally implicate epidermal growth factor receptor-ERK-dependent hormone signaling in this phenotype.

The impact of histologic subtype on primary site surgery in the management of metastatic lobular versus ductal breast cancer: a population based study from the National Cancer Database (NCDB)

PURPOSE

Primary site surgery for metastatic breast cancer improves local control but does not impact overall survival. Whether histologic subtype influences patient selection for surgery is unknown. Given differences in surgical management between early-stage lobular versus ductal disease, we evaluated the impact of histology on primary site surgery in patients with metastatic breast cancer.

METHODS

The National Cancer Database (NCDB, 2010-2016) was queried for patients with stage IV HR-positive, HER2-negative invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC). We compared clinicopathologic features, primary site surgery rates, and outcomes by histologic subtype. Multivariable Cox proportional hazard models with and without propensity score matching were used for overall survival (OS) analyses.

RESULTS

In 25,294 patients, primary site surgery was slightly but significantly less common in the 6,123 patients with ILC compared to the 19,171 patients with IDC (26.9% versus 28.8%, p = 0.004). Those with ILC were less likely to receive chemotherapy (41.3% versus 47.4%, p < 0.0001) or radiotherapy (29.1% versus 37.9%, p < 0.0001), and had shorter OS. While mastectomy rates were similar, those with ILC who underwent lumpectomy had significantly higher positive margin rates (ILC 15.7% versus IDC 11.2%, p = 0.025). In both groups, the odds of undergoing surgery decreased over time, and were higher in younger patients with T2/T3 tumors and higher nodal burden.

CONCLUSION

Lobular histology is associated with less primary site surgery, higher positive margin rates, less radiotherapy and chemotherapy, and shorter OS compared to those with HR-positive HER2-negative IDC. These findings support the need for ILC-specific data and treatment approaches in the setting of metastatic disease.

Successful Breast Conservation After Neoadjuvant Chemotherapy in Lobular Breast Cancer: The Role of Menopausal Status in Response to Treatment

BACKGROUND

While neoadjuvant chemotherapy (NAC) has been shown to increase rates of breast conservation surgery (BCS) for breast cancer, response rates in invasive lobular carcinoma (ILC) appear lower than other histologic subtypes. Some data suggest higher response rates to NAC in premenopausal versus postmenopausal patients, but this has not been studied in ILC. We evaluated the rates of successful BCS after NAC in patients with ILC stratified by menopausal status.

PATIENTS AND METHODS

We analyzed data from a single-institution cohort of 666 patients with stage I-III hormone receptor positive HER-2 negative ILC. We used t-tests, chi-squared tests, and multivariable logistic regression to investigate rates of NAC use, attempted BCS, and associations between NAC and successful BCS by menopausal status.

RESULTS

In 217 premenopausal and 449 postmenopausal patients, NAC was used more often in the premenopausal group (15.2% vs. 9.8%, respectively, p = 0.041). Among those who attempted breast conservation (51.3% of pre- and 64.8% of postmenopausal cohorts), NAC was not associated with successful BCS in either group. Interestingly, for postmenopausal patients, receipt of NAC was significantly associated with increased rates of completion mastectomy in those who had positive margins at the first attempt at BCS.

CONCLUSION

NAC was not associated with successful BCS in either premenopausal or postmenopausal patients with ILC. Although premenopausal patients were more likely to receive NAC, these data suggest that menopausal status may not be a good predictor of response to chemotherapy. Better predictors of response and more efficacious treatment for patients with ILC are needed.

Quantifying hormone receptor status in lobular breast cancer in an institutional series: the relationship between estrogen and progesterone receptor status and outcomes

PURPOSE

Recent guidelines defined a new reporting category of ER-low-positive breast cancer based on immunohistochemistry (IHC). While low positivity of either hormone receptor is uncommon in invasive lobular carcinoma (ILC), we sought to investigate whether relatively low hormone receptor positivity was associated with tumor characteristics and patient outcomes in a single institutional cohort.

METHODS

We searched an institutional database for cases of stage I-III ILC with available IHC reports. Based on prior published categories in ILC, ER was classified as low, medium, or high as defined by ER staining of 10-69%, 70-89%, and ≥ 90% respectively. PR low and high tumors were defined by < 20%, or ≥ 20% staining respectively. We used chi-squared tests, t-tests, and Cox proportional hazards models to evaluate associations between ER/PR categories and tumor characteristics or disease-free survival (DFS).

RESULTS

The cohort consisted of 707 ILC cases, with 11% of cases categorized as ER low, 15.1% as medium, and 73.8% as high. The majority (67.6%) were PR high. Patients with ER low/medium expression were significantly younger, and more likely to also have PR low and/or HER2 positive tumors compared to those that were ER high. In a Cox proportional hazards model adjusting for age, stage, grade, pleomorphic histology, and treatment, ER category was not prognostic for DFS, but PR negative and PR low status each had significantly worse DFS compared to PR high status (HR 3.5, 95% CI 1.8-6.7, p < 0.001; and HR 2.0, 95% CI 1.1-3.5, p = 0.015, respectively).

CONCLUSION

These findings highlight the relevance of quantifying ER and PR within ILC.

Tamoxifen or aromatase inhibitors with ovarian function suppression in pre-menopausal stage I-III lobular breast cancer

While adjuvant treatment with the selective-estrogen receptor modulator (SERM) tamoxifen has been the standard of care for pre-menopausal patients with hormone receptor (HR) positive breast cancer, recent trials showed a benefit of aromatase inhibitors (AI) and ovarian function suppression (OFS) for some patients. The approach to endocrine therapy has not been well studied in pre-menopausal patients with invasive lobular carcinoma (ILC). We identified 202 pre-menopausal patients with HR positive stage I-III ILC in an institutional database. We investigated factors associated with endocrine therapy type and determined changes in systemic therapy from 1990-2021. We evaluated associations between endocrine therapy type and disease-free survival (DFS) with a multivariate Cox proportional hazards model. Of 202 patients, most (69.3%) were prescribed a SERM (99.3% tamoxifen). Those who received an AI had significantly higher stage disease. Over time, use of OFS and AI increased significantly in stage II or III cases (from 0% in 1990 to 56% after 2015 for stage II; from 0% to 80% after 2015 for stage III). Concurrently, adjuvant chemotherapy use significantly decreased in stage II cases (from 67% to 19%). In an exploratory multivariable model, longer duration of AI compared to tamoxifen was associated with significantly improved DFS (HR 0.31; 95% CI 0.11-0.86; p = 0.025). While most pre-menopausal patients received adjuvant tamoxifen, the use of OFS and AIs increased significantly over time. The association between AI use and improved DFS may be consistent with prior randomized trials and warrants further investigation into predictive factors to guide treatment selection.

Predictors of Early Versus Late Recurrence in Invasive Lobular Carcinoma of the Breast: Impact of Local and Systemic Therapy

BACKGROUND

Invasive lobular carcinoma (ILC) of the breast is known for high risk of late recurrence, yet some patients still recur within 5 years of diagnosis. Determining factors associated with early/late recurrence could help tailor treatment and surveillance strategies.

METHODS

Using an institutional database, we evaluated patients with ILC and ≥ 5 years of follow-up or recurrence within 5 years. We used multivariate logistic regression and the Kaplan-Meier method to evaluate which clinicopathologic features and treatment strategies were associated with recurrence < 5 years since diagnosis versus recurrence ≥ 5 years since diagnosis. Additionally, we explored the association between Clinical Treatment Score 5 (CTS5) with early versus late recurrence.

RESULTS

Among 513 cases of stage I-III ILC, there were 75 early and 54 late recurrences during a median follow-up period of 9.4 years. Early recurrence was associated with larger tumors (mean 4.2 cm vs. 2.9 cm, p < 0.0001), higher incidence of > 3 positive nodes (32.4% vs. 9.11%, p > 0.0001), and more aggressive tumor biology (low/negative progesterone receptor expression, higher grade, and higher Ki67). Late recurrence was associated with younger age (mean 55.6 vs. 59.2 years, p = 0.037) and elevated body mass index (BMI > 25 kg/m2 in 60.1.0% vs. 45.4%, p = 0.021). Omission of adjuvant endocrine therapy or radiotherapy after lumpectomy conferred increased risk of early rather than late recurrence.

CONCLUSION

Factors related to tumor aggressiveness and treatment were associated with early recurrence, whereas patient related factors were related to late recurrence. These data may help guide treatment strategies and surveillance approaches for patients with ILC.

Changes in Surgical Management of the Axilla Over 11 Years - Report on More Than 1500 Breast Cancer Patients Treated with Neoadjuvant Chemotherapy on the Prospective I-SPY2 Trial

BACKGROUND

Axillary surgery after neoadjuvant chemotherapy (NAC) is becoming less extensive. We evaluated the evolution of axillary surgery after NAC on the multi-institutional I-SPY2 prospective trial.

METHODS

We examined annual rates of sentinel lymph node (SLN) surgery with resection of clipped node, if present), axillary lymph node dissection (ALND), and SLN and ALND in patients enrolled in I-SPY2 from January 1, 2011 to December 31, 2021 by clinical N status at diagnosis and pathologic N status at surgery. Cochran-Armitage trend tests were calculated to evaluate patterns over time.

RESULTS

Of 1578 patients, 973 patients (61.7%) had SLN-only, 136 (8.6%) had SLN and ALND, and 469 (29.7%) had ALND-only. In the cN0 group, ALND-only decreased from 20% in 2011 to 6.25% in 2021 (p = 0.0078) and SLN-only increased from 70.0% to 87.5% (p = 0.0020). This was even more striking in patients with clinically node-positive (cN+) disease at diagnosis, where ALND-only decreased from 70.7% to 29.4% (p < 0.0001) and SLN-only significantly increased from 14.6% to 56.5% (p < 0.0001). This change was significant across subtypes (HR-/HER2-, HR+/HER2-, and HER2+). Among pathologically node-positive (pN+) patients after NAC (n = 525) ALND-only decreased from 69.0% to 39.2% (p < 0.0001) and SLN-only increased from 6.9% to 39.2% (p < 0.0001).

CONCLUSIONS

Use of ALND after NAC has significantly decreased over the past decade. This is most pronounced in cN+ disease at diagnosis with an increase in the use of SLN surgery after NAC. Additionally, in pN+ disease after NAC, there has been a decrease in use of completion ALND, a practice pattern change that precedes results from clinical trials.

Erratum: 53 The development of a multi-institutional prospective registry for patients with metastatic invasive lobular carcinoma: identifying new markers of disease progression - CORRIGENDUM

[This corrects the article DOI: 10.1017/cts.2023.142.].

Breast Conservation Surgery and Mastectomy Have Similar Locoregional Recurrence After Neoadjuvant Chemotherapy: Results From 1462 Patients on the Prospective, Randomized I-SPY2 Trial

Neoadjuvant chemotherapy (NAC) increases rates of successful breast-conserving surgery (BCS) in patients with breast cancer. However, some studies suggest that BCS after NAC may confer an increased risk of locoregional recurrence (LRR). We assessed LRR rates and locoregional recurrence-free survival (LRFS) in patients enrolled on I-SPY2 (NCT01042379), a prospective NAC trial for patients with clinical stage II to III, molecularly high-risk breast cancer. Cox proportional hazards models were used to evaluate associations between surgical procedure (BCS vs mastectomy) and LRFS adjusted for age, tumor receptor subtype, clinical T category, clinical nodal status, and residual cancer burden (RCB). In 1462 patients, surgical procedure was not associated with LRR or LRFS on either univariate or multivariate analysis. The unadjusted incidence of LRR was 5.4% after BCS and 7.0% after mastectomy, at a median follow-up time of 3.5 years. The strongest predictor of LRR was RCB class, with each increasing RCB class having a significantly higher hazard ratio for LRR compared with RCB 0 on multivariate analysis. Triple-negative receptor subtype was also associated with an increased risk of LRR (hazard ratio: 2.91, 95% CI: 1.8-4.6, P < 0.0001), regardless of the type of operation. In this large multi-institutional prospective trial of patients completing NAC, we found no increased risk of LRR or differences in LRFS after BCS compared with mastectomy. Tumor receptor subtype and extent of residual disease after NAC were significantly associated with recurrence. These data demonstrate that BCS can be an excellent surgical option after NAC for appropriately selected patients.

Area Deprivation Index in Patients with Invasive Lobular Carcinoma of the Breast: Associations with Tumor Characteristics and Outcomes

BACKGROUND

Although investigators have shown associations between socioeconomic status (SES) and outcomes in breast cancer, there is a paucity of such data for invasive lobular carcinoma (ILC), the second most common type of breast cancer. Herein we evaluated the relationship between SES with tumor features and outcomes in stage I to III patients with ILC.

METHODS

We analyzed a prospectively maintained institutional ILC database and utilized the area deprivation index (ADI) to determine neighborhood adversity, an indicator of SES. We used Cox proportional hazards models in Stata 17.0 to evaluate relationships between ADI quintile (Q), race, body mass index (BMI), clinicopathologic features, treatment type, and event-free survival (EFS).

RESULTS

Of 804 patients with ILC, 21.4% lived in neighborhoods classified as ADI Q1 (least resource-deprived) and 19.7% in Q5 (most resource-deprived). Higher deprivation was significantly associated with larger tumor size (3.6 cm in Q5 vs. 3.1 cm in Q1), increased presence of lymphovascular invasion (8.9% in Q5 vs. 6.7% in Q1), and decreased use of adjuvant endocrine therapy (67.1% in Q5 vs. 73.6% in Q1). On multivariable analysis, tumor size, receptor subtypes, and omission of adjuvant endocrine therapy were associated with reduced EFS.

CONCLUSIONS

These data show that patients with ILC and higher ADI experience more aggressive tumors and differences in treatment. More data evaluating the complex relationships between these factors is needed to optimize outcomes for patients with ILC, regardless of SES.

IMPACT

ADI is associated with differences in patients with ILC.

The impact of histologic subtype on primary site surgery in the management of metastatic lobular versus ductal breast cancer: a population based study from the National Cancer Database

Purpose

Primary site surgery for metastatic breast cancer improves local control but does not impact overall survival. Whether histologic subtype influences patient selection for surgery is unknown. Given differences in surgical management between early-stage lobular versus ductal disease, we evaluated the impact of histology on primary site surgery in patients with metastatic breast cancer.

Methods

The National Cancer Database (NCDB, 2010-2016) was queried for patients with stage IV HR-positive, HER2-negative invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC). We compared clinicopathologic features, primary site surgery rates, and outcomes by histologic subtype. Multivariable Cox proportional hazard models with and without propensity score matching were used for overall survival (OS) analyses.

Results

In 25,294 patients, primary site surgery was slightly but significantly less common in the 6,123 patients with ILC compared to the 19,171 patients with IDC (26.9% versus 28.8%, p = 0.004). Those with ILC were less likely to receive chemotherapy (41.3% versus 47.4%, p < 0.0001) or radiotherapy (29.1% versus 37.9%, p < 0.0001), and had shorter OS. While mastectomy rates were similar, those with ILC had more positive margins (10.6% versus 8.3%, p = 0.005). In both groups, the odds of undergoing surgery decreased over time, and were higher in younger patients with T2/T3 tumors and higher nodal burden.

Conclusion

Lobular histology is associated with less primary site surgery, higher positive margin rates, less radiotherapy and chemotherapy, and shorter OS compared to those with HR-positive HER2-negative IDC. These findings support the need for ILC-specific data and treatment approaches in the setting of metastatic disease.

HER-2 low status in early-stage invasive lobular carcinoma of the breast: associated factors and outcomes in an institutional series

PURPOSE

HER2 overexpression has a central role in breast cancer carcinogenesis and is associated with poor prognosis if untreated. Lately, identification of HER2-low breast cancer has been proposed to select patients for novel HER2-directed chemotherapy and includes cancers with immunohistochemistry 1 + or 2 + with negative FISH, encompassing approximately 55-60% of all breast carcinomas. In early-stage breast cancer, the prognostic significance of HER2 low-disease is less well understood, with a particular paucity of data evaluating the prevalence and implications of HER2-low status in invasive lobular carcinoma (ILC).

METHODS

We evaluated 666 stage I-III ILC tumors from a prospectively maintained institutional database, comparing clinicopathologic features and disease-free survival (DFS) using a multivariable Cox proportional hazards model.

RESULTS

HER2-low status was common in this cohort of patients with ILC, but most clinicopathologic features did not differ between HER2-low and HER2-negative cases. However, when adjusting for tumor size, number of positive nodes, ER/PR status, and local therapy received, patients with HER2-low status had worse disease-free survival (DFS) than those with HER2-negative tumors (hazard ratio 2.0, 95% confidence interval 1.0-4.1, p = 0.05).

CONCLUSION

This difference in DFS supports the notion that HER2-low and HER2-negative early stage ILC may differ clinically, despite similar clinicopathologic features. Further investigation into the potential benefit of HER2 targeted therapy in HER2-low early-stage breast cancer, and specifically lobular cancer, is warranted to ensure optimal outcomes in this distinct tumor subtype.

Identifying Good Candidates for Active Surveillance of Ductal Carcinoma In Situ: Insights from a Large Neoadjuvant Endocrine Therapy Cohort

Ductal carcinoma in situ (DCIS) is a biologically heterogenous entity with uncertain risk for invasive ductal carcinoma (IDC) development. Standard treatment is surgical resection often followed by radiation. New approaches are needed to reduce overtreatment. This was an observational study that enrolled patients with DCIS who chose not to pursue surgical resection from 2002 to 2019 at a single academic medical center. All patients underwent breast MRI exams at 3- to 6-month intervals. Patients with hormone receptor-positive disease received endocrine therapy. Surgical resection was strongly recommended if clinical or radiographic evidence of disease progression developed. A recursive partitioning (R-PART) algorithm incorporating breast MRI features and endocrine responsiveness was used retrospectively to stratify risk of IDC. A total of 71 patients were enrolled, 2 with bilateral DCIS (73 lesions). A total of 34 (46.6%) were premenopausal, 68 (93.2%) were hormone-receptor positive, and 60 (82.1%) were intermediate- or high-grade lesions. Mean follow-up time was 8.5 years. Over half (52.1%) remained on active surveillance without evidence of IDC with mean duration of 7.4 years. Twenty patients developed IDC, of which 6 were HER2 positive. DCIS and subsequent IDC had highly concordant tumor biology. Risk of IDC was characterized by MRI features after 6 months of endocrine therapy exposure; low-, intermediate-, and high-risk groups were identified with respective IDC rates of 8.7%, 20.0%, and 68.2%. Thus, active surveillance consisting of neoadjuvant endocrine therapy and serial breast MRI may be an effective tool to risk-stratify patients with DCIS and optimally select medical or surgical management.

Significance

A retrospective analysis of 71 patients with DCIS who did not undergo upfront surgery demonstrated that breast MRI features after short-term exposure to endocrine therapy identify those at high (68.2%), intermediate (20.0%), and low risk (8.7%) of IDC. With 7.4 years mean follow-up, 52.1% of patients remain on active surveillance. A period of active surveillance offers the opportunity to risk-stratify DCIS lesions and guide decisions for operative management.

Association of Residual Ductal Carcinoma In Situ With Breast Cancer Recurrence in the Neoadjuvant I-SPY2 Trial

Importance

Pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer strongly correlates with overall survival and has become the standard end point in neoadjuvant trials. However, there is controversy regarding whether the definition of pCR should exclude or permit the presence of residual ductal carcinoma in situ (DCIS).

Objective

To examine the association of residual DCIS in surgical specimens after neoadjuvant chemotherapy for breast cancer with survival end points to inform standards for the assessment of pathologic complete response.

Design, Setting, and Participants

The study team analyzed the association of residual DCIS after NAC with 3-year event-free survival (EFS), distant recurrence-free survival (DRFS), and local-regional recurrence (LRR) in the I-SPY2 trial, an adaptive neoadjuvant platform trial for patients with breast cancer at high risk of recurrence. This is a retrospective analysis of clinical specimens and data from the ongoing I-SPY2 adaptive platform trial of novel therapeutics on a background of standard of care for early breast cancer. I-SPY2 participants are adult women diagnosed with stage II/III breast cancer at high risk of recurrence.

Interventions

Participants were randomized to receive taxane and anthracycline-based neoadjuvant therapy with or without 1 of 10 investigational agents, followed by definitive surgery.

Main Outcomes and Measures

The presence of DCIS and EFS, DRFS, and LRR.

Results

The study team identified 933 I-SPY2 participants (aged 24 to 77 years) with complete pathology and follow-up data. Median follow-up time was 3.9 years; 337 participants (36%) had no residual invasive disease (residual cancer burden 0, or pCR). Of the 337 participants with pCR, 70 (21%) had residual DCIS, which varied significantly by tumor-receptor subtype; residual DCIS was present in 8.5% of triple negative tumors, 15.6% of hormone-receptor positive tumors, and 36.6% of ERBB2-positive tumors. Among those participants with pCR, there was no significant difference in EFS, DRFS, or LRR based on presence or absence of residual DCIS.

Conclusions and Relevance

The analysis supports the definition of pCR as the absence of invasive disease after NAC regardless of the presence or absence of DCIS.

Trial Registration

ClinicalTrials.gov Identifier NCT01042379.

The 21-Gene Recurrence Score in Clinically High-Risk Lobular and Ductal Breast Cancer: A National Cancer Database Study

Objective

The aim of this study was to evaluate whether patients with invasive lobular carcinoma (ILC) are more likely to have discordant clinical and genomic risk than those with invasive ductal carcinoma (IDC) when using the 21-gene recurrence score (RS), and to assess overall survival outcomes of patients with 1–3 positive nodes and RS ≤25 with and without chemotherapy, stratified by histology.

Methods

We performed a cohort study using the National Cancer Database and included patients with hormone receptor-positive, HER2-negative, stage I–III invasive breast cancer who underwent 21-gene RS testing. Our primary outcome was rate of discordant clinical and genomic risk status by histologic subtype. Propensity score matching was used to compare 60-month overall survival in individuals with 1–3 positive nodes and RS ≤25 who did and did not receive chemotherapy.

Results

Overall, 186,867 patients were included in our analysis, including 37,685 (20.2%) patients with ILC. There was a significantly higher rate of discordant clinical and genomic risk in patients with ILC compared with IDC. Among patients with 1–3 positive nodes and RS ≤25, there was no significant difference in survival between those who did and did not receive chemotherapy in the IDC or ILC cohorts. Unadjusted exploratory analyses of patients under age 50 years with 1–3 positive nodes and RS ≤25 showed improved overall survival in IDC patients who received chemotherapy, but not among those with ILC.

Conclusion

Our findings highlight the importance of lobular-specific tools for stratifying clinical and genomic risk, as well as the need for histologic subtype-specific analyses in randomized trials.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-022-12065-3.

Pathologic complete response (pCR) rates for HR+/HER2- breast cancer by molecular subtype in the I-SPY2 Trial

504

Background: Hormone receptor positive (HR+), HER2- breast cancer (BC) is a heterogenous disease. We hypothesized that molecular subtypes capturing luminal, basal, and immune biology could predict response for patients (pts) with HR+/HER2- disease in the I-SPY2 trial. Methods: I-SPY2 trial is a phase II, randomized, adaptive study evaluating multiple investigational agents as neoadjuvant BC therapy; the primary endpoint is estimated pCR rate. Investigational agents are given with control weekly paclitaxel x 12, followed by AC x 4. Regimens graduate when the predicted pCR rate in any signature meets the pre-specified threshold of 85% probability of success in a hypothetical 300 pt randomized, phase 3 trial. We analyzed estimated pCR rates for the 1st 7 investigational agents in the HR+/HER- subset, analyzed by clinical/molecular features: BluePrint (BP) Luminal vs. Basal, Mammaprint High1 [MP1] vs. Mammaprint High2 [MP2], MP2 is < -0.57, Responsive Predictive Subtype-5 (RPS-5) (classification based on HR, HER2, immune, DNA-repair, and basal/luminal markers), histology, and stage/nodal status. Results: 38% (379/987) of pts had HR+/HER2- disease. Only pembrolizumab met the pre-specified graduation criteria for HR+/HER2- BC. pCR rates by treatment arm and molecular subtype are described in the Table. 28% were MP2; 72% were MP1. Overall, pCR rates were higher in pts with MP2 vs MP1 disease (30% vs 11%) including with pembrolizumab (55% vs. 21%). 29% were BP Basal, 71% were BP Luminal; BP Basal was more likely to be MP2 than BP Luminal (77% vs 8%). In all arms except MK2206, HR+/HER2- BP Basal pts were more likely to achieve pCR than BP Luminal pts. For MK2206, BP Luminal pts were more likely to achieve pCR. Immune+ by RPS-5 (39% of HR+/HER2-) predicted pCR to pembrolizumab irrespective of BP Basal or Luminal status (11 pCR/16 pts). Results by histology and stage/nodal status will also be reported. Conclusions: Our data suggest that MP2 and BP Basal signatures identify a subset of HR+/HER2- BC more likely to respond to neoadjuvant therapy; and that an immune signature can identify pts more likely to respond to pembrolizumab. These findings will aid in guiding prioritization of targeted agents with the goal to optimize pCR for all pts. Clinical trial information: NCT01042379. [Table: see text]

Abstract P3-02-02: FES-dedicated breast PET uptake in early-stage ER+ breast cancers

BACKGROUND: Patients with ER+ breast cancer may have a recurrence risk of aggressive disease. While clinical evidence suggests that ER+ tumors are responsive to endocrine therapy, up to one-third of patients with early-stage ER+ disease may not respond to endocrine therapy. Tumor biologic factors such as ER functionality, cell proliferation, and molecular traits may influence endocrine treatment responsiveness and long-term recurrence risk. More comprehensive tools are needed to depict the primary breast tumor. [18F]fluoroestradiol (FES) is a radiotracer developed for positron emission tomography (PET) imaging of ER status. We used FES with a high-resolution dedicated breast PET (dbPET) to quantify ER expression in primary ER+ tumors and assessed the relationship between FES uptake and tumor characteristics. METHODS: With IRB approval, patients with biopsy-proven ER+/HER2- breast cancer were imaged using dbPET with 5 mCi of FES before treatment. FES uptake (SUVmax, SUVmean, and SUVpeak), background parenchymal uptake (BPU), tumor uptake volume (TUV), and tumor to background ratio (TBR) were calculated. Background values (SUVbkg) were obtained from the normal region of the ipsilateral breast. Lesions with background-corrected SUVmax 2 times higher than SUVbkg were considered FES avid. Tumor size (longest diameter) was measured by MRI. The histologic subtype, ER expression, tumor grade, and Ki67 were obtained from core biopsies before treatment. Ki67 was dichotomized to low and high using a 20% cutoff. Spearman’s rank correlation was used to assess the correlation between FES uptake and tumor size. Differences between FES uptake, histologic subtype, and Ki67 were compared using a Wilcoxon rank-sum test. RESULTS: 19 treatment-naïve patients were included in this analysis as part of an ongoing study. Patient and tumor characteristics are listed in Table 1. While all patients had ER positivity &gt;90% by immunohistochemistry (IHC), we observed varying FES avidity in ER+ breast cancers, with 14 FES avid and 5 non-FES avid lesions. There was a statistically significant difference between FES avid vs. non-avid lesions measured by all uptake metrics except BPU. FES uptake in invasive ductal carcinoma was similar to invasive lobular carcinoma. FES uptake correlated with tumor size, with the highest correlation ρ = 0.58, 95% CI (0.17, 0.84), p=0.012, detected in TUV. FES uptake was associated with Ki67, with all uptake metrics except BPU showing a statistically significant difference between high and low Ki67 expression (Table 2). CONCLUSION: We found that not all lesions that were highly ER+ by IHC were FES avid. FES-dbPET captures information from the entire tumor, providing a more comprehensive assessment of functional ER status than IHC of a limited tumor sample. Moreover, FES uptake correlates with tumor size and cell proliferation. This is an ongoing study; additional data may help to guide endocrine therapy decisions. Future studies with a larger cohort are planned to assess the relationship between FES uptake and tumor grade and molecular risk profiles.

Table 1.Patient and tumor characteristicsCharacteristicsNo. of patientsTotal N=19Age (median (IQR))56.0 (21.5)Pre-menopausal7Post-menopausal12Histologic subtypeInvasive ductal carcinoma (IDC)6Invasive lobular carcinoma (ILC)13Tumor size (N=18) (MRI LD (cm), median (IQR))3.2 (4.1)Tumor grade1421332Ki67Low12High6Unknown1FESNon-avid5Avid14

Table 2.Summary of baseline FES uptake valuesTumor Size (cm)FES AvidityHistologic SubtypeKi67Spearman CorrelationAvid vs. Non-avidILC vs. IDCHigh vs. Lowρ (95%CI)P-valueMedian Diff (95%CI)P-valueMedian Diff (95%CI)P-valueMedian Diff (95%CI)P-valueSUVmax0.51 (0.054, 0.79)0.0318.02 (3.55, 11.9)0.0010.187 (-8.04, 6.32)0.976.38 (2.36, 11.6)0.017SUVmean0.31 (-0.18, 0.68)0.2042.42 (1.47, 3.49)0.001-0.477 (-1.96, 1.37)0.571.61 (0.81, 2.77)0.028SUVpeak0.46 (-0.0053, 0.76)0.0533.16 (1.42, 5.2)0.003-0.583 (-3.76, 2.61)0.633.16 (1.32, 4.66)0.013BPU-0.09 (-0.53, 0.39)0.723-0.33 (-1.25, 0.46)0.3790.226 (-0.58, 1.19)0.40-0.49 (-1.49, 0.28)0.122TUV (cm3)0.58 (0.15, 0.82)0.0125.45 (1.09, 12.5)0.005-2.82 (-12.5, 4.06)0.405.9 (0.98, 12.66)0.021TBR0.5 (0.047, 0.79)0.0333.48 (2.2, 13.5)0.001-0.295 (-11.9, 7.42)0.9010.2 (1.47, 13.49)0.028

Citation Format: Ella F. Jones, Deep K. Hathi, Julissa Molina-Vega, David C. Newitt, Courtney Lawhn-Heath, Kimberly M. Ray, Bonnie N. Joe, Diane Heditsian, Susie Brain, Rita A. Mukhtar, A. Jo Chien, Hope S. Rugo, I-SPY 2 TRIAL Consortium, I-SPY 2 TRIAL Imaging Working Group, Laura J. Esserman, Nola M. Hylton. FES-dedicated breast PET uptake in early-stage ER+ breast cancers [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-02.

Abstract P2-02-02: Differences in levels of circulating tumor cells (CTC) and disseminated tumor cells (DTC) in early-stage lobular versus ductal breast cancer

Background: Invasive lobular carcinoma (ILC) is the second most common type of breast cancer after invasive ductal carcinoma (IDC). ILC has unique features, such as a diffuse growth pattern due to characteristic loss of E cadherin, and a different pattern of disease metastasis compared to IDC. Prior investigators have shown increased numbers of circulating tumor cells (CTCs) in patients with metastatic ILC versus IDC. We explored the distribution of CTCs and disseminated tumor cells (DTCs) in early stage ILC versus IDC. Methods: We performed a secondary data analysis of the TIPPING study, an institutional review board approved study that pre-operatively collected blood and bone marrow samples from 655 treatment-naïve early-stage breast cancer patients. We analyzed data from 284 patients who had CTCs and DTC enumerated by an EPCAM-based method involving immunomagnetic enrichment and flow cytometry (IE/FC) (61 patients with ILC and 223 patients with IDC). We compared CTC and DTC counts by histology using the Welch Two Sample t-test, linear regression models, as well as ANOVA tests. Multivariate Cox regression analyses were performed to assess association between levels of CTCs/DTCs and clinical outcomes (distant recurrence-free survival [DRFS] and breast cancer-specific survival [BCSS]). Results: ILC tumors were lower grade than IDCs and had a higher proportion of HR+HER2- subtypes (92.00% vs. 75.30%; p&lt;0.001). ILC patients had significantly higher CTC counts than IDC patients (mean 2.11 vs. 0.71 CTCs/mL; p&lt;0.001), a difference that retained significance after adjusting for clinical variables (p=0.003). Additionally, we identified a subset of ILC patients (n = 9; 14.75%) that have elevated CTCs, which was absent in the IDC subset. ILC patients with elevated CTC levels showed no statistically significant association between CTC as a continuous variable with nodal status and breast cancer stage (p=0.26, p=0.25, respectively). In our study, the overall median follow-up was 7.26 years for DRFS and 8.9 years for BCSS. In the subset of ILC patients with elevated CTCs, CTC level as a continuous variable did not show significant association with DRFS or BCSS in a multivariate model adjusting for clinical variables. In the IDC subset, CTC level as a continuous variable did not show significant association with DRFS or BCSS in a multivariate model adjusting for clinical variables.Furthermore, there was no difference in the number of DTCs in ILC versus IDC. DTC level as a continuous variable did not show significant association with DRFS or BCSS in a multivariate model adjusting for clinical variables in both ILC and IDC subsets. Conclusions: Early-stage ILC patients have significantly higher CTC levels than those observed in IDC patients, and we hypothesize that the reason may be due to lower cell-cell adhesion. ILC spans the spectrum of indolent (benign) to high risk (bad actor) disease. Thus, biomarkers like CTCs may allow us to identify ILC patients who are at higher risk of late recurrence and make appropriate therapeutic decisions at earlier point in time. Studies like Endocrine Optimization Pilot in I-SPY 2 are ongoing to further investigate the use of biomarkers like CTCs to inform outcomes. Due to the short follow-up period, we will conduct an additional follow-up which should give us 10 years of follow-up, which is likely needed due to the risk for late recurrence in ILC patients.

Citation Format: Silver Alkhafaji, Denise Wolf, Mark Magbanua, Laura Van 't Veer, John Park, Laura J. Esserman, Rita A. Mukhtar. Differences in levels of circulating tumor cells (CTC) and disseminated tumor cells (DTC) in early-stage lobular versus ductal breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-02-02.

Abstract P3-02-01: Initial experience of FES-dedicated breast PET imaging of early-stage ER+ invasive lobular carcinoma

BACKGROUND: Invasive lobular carcinoma (ILC) is the second most common histological subtype of breast cancer, representing 15% of all invasive breast cancers. Most ILC tumors are estrogen receptor-positive (ER+) and may respond to endocrine therapy. However, tumor biologic factors such as ER functionality, cell proliferation, and molecular traits may influence endocrine treatment response and long-term recurrence risk, thus necessitating a comprehensive approach to characterize the primary breast tumor. [18F]fluoroestradiol (FES) is a radiotracer developed for positron emission tomography (PET) imaging of ER status. For this work, we studied the utility of imaging FES uptake in early-stage primary ER+ ILC lesions, using high-resolution dedicated breast PET (dbPET) to assess the relationship between FES uptake and tumor characteristics. METHODS: With institutional review board approval, patients with biopsy-proven ER+/HER2- ILC were prospectively imaged using dbPET with 5 mCi of FES before treatment. FES uptake (SUVmax, SUVmean, and SUVpeak), tumor uptake volume (TUV), and background parenchymal uptake (BPU) values were calculated. Background values (SUVbkg) were obtained from the normal region of the ipsilateral breast. Lesions with background-corrected SUVmax 2 times higher than SUVbkg were considered FES-avid. Tumor grade, Ki67 cell proliferation index, and ER expression were obtained from core biopsies before treatment. Ki67 was dichotomized to low and high using a 20% cutoff1. Tumor size (longest diameter) was measured by magnetic resonance imaging (MRI). Spearman rank correlation was used to assess the relationship between FES uptake and tumor size. Differences between FES uptake at high and low Ki67 were compared using a Wilcoxon rank-sum test. RESULTS: 13 treatment-naïve ILC patients aged 32-82 years were included in this analysis (Table 1). Despite all lesions exhibiting strongly positive ER expression &gt;90% by immunohistochemistry (IHC), we observed varying FES avidity with 9 FES avid and 4 FES non-avid ILC lesions. SUVmax, TUV, and TBR had substantial median differences between Ki67 high and low lesions (5.9, 4.3, and 9.6, respectively), but the difference did not achieve statistical significance. FES tumor uptake also correlated with tumor size, with the highest correlation observed for SUVpeak (ρ = 0.71 (95% CI: 0.22, 0.91), p=0.010) (Table 2). CONCLUSION: We found that not all highly ER expressing ILC by IHC were FES-avid. As FES-dbPET captures information from the entire tumor, it provides a more comprehensive assessment of functional ER status than IHC of a limited tumor sample. FES uptake in ILC also relates to tumor size and Ki67. This is an ongoing study; additional data may help to guide endocrine therapy decisions. Future studies with a larger cohort are planned to assess the relationship between FES uptake and tumor grade and molecular risk profiles. 1. Acs, B. et al. Ki-67 as a controversial predictive and prognostic marker in breast cancer patients treated with neoadjuvant chemotherapy. Diagn Pathol 12, 20, doi:10.1186/s13000-017-0608-5 (2017).

Patient and tumor characteristicsCharacteristicsNumber of patients (Total N=13)Age (median (range))56.0 (32-80)Pre-menopausal3Post-menopausal10MRI tumor size (median (interquartile range)4.1 (2.4-6.8)Tumor grade132931Ki6712Low/High3/9FES13Avid/Non-avid9/4

Summary of FES uptake values and correlation coefficients.FES avidity (N=13)Ki67 (N=12)MRI tumor size (N=12)Avid vs Non-avidHigh vs LowSpearman rank correlationMedian Difference (95% CI)P-valueMedian Difference (95% CI)P-valueSpearman ρ (95% CI)P-valueSUVmax8.68 (2.86, 12)0.0075.9 (-19.5, 11.6)0.140.67 (0.16, 0.9)0.017SUVmean2.56 (1.43, 4.86)0.0071.34 (-4.14, 3.1)0.200.6 (0.042, 0.87)0.039SUVpeak2.86 (1.14, 4.59)0.0112.15 (-14.4, 3.72)0.190.71 (0.22, 0.91)0.01BPU-0.31 (-1.89, 1.02)0.82-0.73 (-2.34, 0.28)0.0960.01 (-0.57, 0.58)0.98TUV (cm3)5.45 (1.04, 10)0.014.3 (-185, 10)0.190.70 (0.21, 0.91)0.011TBR3.61 (2.2, 13)0.0079.57 (-19.6, 12.4)0.0640.66 (0.13, 0.89)0.02

Citation Format: Ella F Jones, Deep K Hathi, Natalia Konovalova, Julissa Molina-Vega, David C Newitt, Courtney Lawhn-Heath, Kimberly M Ray, Bonnie N Joe, Diane Heditsian, Susie Brain, I-SPY 2 TRIAL Imaging Working Group, I-SPY 2 TRIAL Consortium, A. Jo Chien, Laura J Esserman, Nola M Hylton, Rita A Mukhtar. Initial experience of FES-dedicated breast PET imaging of early-stage ER+ invasive lobular carcinoma [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-02-01.

Abstract P3-03-07: Single-institution retrospective analysis of lymph node (LN) change on breast MRI in patients with high risk early-stage breast cancer receiving neoadjuvant chemotherapy with and without immunotherapy on the ISPY-2 TRIAL

Background: The I-SPY2 TRIAL has shown that the addition of pembrolizumab to standard neoadjuvant chemotherapy results in improved rates of estimated pathologic complete response (pCR) for hormone-receptor positive (HR+) as well as triple negative breast cancer (TNBC). I-SPY2 has tested a number of novel immunotherapy combinations including the combination of pembrolizumab and SD-101, a synthetic oligonucleotide with cytidine-phospho-guanosine (CpG) motifs that stimulates plasmacytoid dendritic cells (pDC) through engagement of toll-like receptor 9 (TLR9). Biomarkers of response to immunotherapy may be different than chemotherapy, and pathologic response may not fully reflect the benefit from checkpoint inhibitors. Early markers of response to immunotherapy are needed to minimize the risk of immune-related toxicity in patients who are unlikely to benefit. The objective of this study is to assess the change in regional lymph nodes (LNs) by breast MRI in I-SPY2 patients receiving neoadjuvant chemotherapy +/- immunotherapy, and to explore if changes in regional LNs correlate with pCR and residual cancer burden (RCB). Methods: This is a retrospective study of the prospective multicenter I-SPY2 adaptive neoadjuvant trial investigating all patients enrolled at UCSF in 3 study arms between Dec 2015 and April 2021: 1) Control (weekly paclitaxel 80 mg/m2 x 12 weeks followed by AC x 4); 2) weekly paclitaxel + pembrolizumab 200 mg IV every 3 weeks, followed by AC x 4; 3) weekly paclitaxel + every 3 week pembrolizumab + intra-tumoral SD-101 weekly x 4 then every 3 weeks x 2 followed by AC x 4. Serial pre-operative breast MRIs were performed in all patients at baseline, 3 weeks, 12 weeks, and 20 weeks. A single breast radiologist blinded to treatment arm reviewed all MRIs for all patients included in this study and assessed longest diameter and cortical thickness of the largest ipsilateral axillary LN, number and location of abnormal LNs, and development of new abnormal LNs over time. Rates of pCR and RCB were evaluated in patients who showed evidence of LN growth and/or development of new lymphadenopathy (LAD) compared to those who did not. A two-sample test for equality of proportions to measure the statistical significance at alpha=.5 between control and immunotherapy arms and LN change was used. Results: A total of 43 patients were included, of whom 16 were in the control group, 11 received pembrolizumab, and 16 received pembrolizumab + SD-101. Median age was 45 years, mean tumor size was 4.8 cm, and 60% of tumors were HR+HER2-negative with the remaining 40% being TNBC. Baseline patient and tumor characteristics were similar between the 3 study arms. LN enlargement and/or development of new LAD over time was significantly more common in patients receiving immunotherapy than patients in the control arm (48.1% versus 6.3%, p=0.006). This was seen in both HR+ and TN subtypes. While there was a numerically higher rate of pCR/RCB-1 pathology in patients with increased and/or new LAD compared to those without (64% vs 51%), this difference was not statistically significant. The association of LN change and immune-related toxicities will be reported. Conclusion: The addition of immunotherapy to standard neoadjuvant chemotherapy in the I-SPY2 trial was associated with an increase in size of ipsilateral axillary LN and/or development of new LAD on serial breast MRI imaging during the course of neoadjuvant treatment. These changes were not associated with worse pathologic response at surgery and should not be assumed to be due to disease progression. Whether these changes could reflect immunotherapy benefit needs to be investigated in a larger trial with longer follow-up.

Citation Format: Anika Christofferson, Elissa Price, Rita A Mukhtar, Amrita Basu, Laura Esserman, A Jo Chien. Single-institution retrospective analysis of lymph node (LN) change on breast MRI in patients with high risk early-stage breast cancer receiving neoadjuvant chemotherapy with and without immunotherapy on the ISPY-2 TRIAL [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-03-07.

Obesity and menopausal status impact the features and molecular phenotype of invasive lobular breast cancer

Purpose

We investigated the relationship between obesity, menopausal status, and invasive lobular carcinoma (ILC), the second most common histological subtype of breast cancer. Specifically, we evaluated the association between body mass index (BMI), metabolic syndrome, the 21-gene Oncotype Recurrence Score (Oncotype RS), and pathological features in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor-2-negative ILC.

Methods

The study cohort included 491 patients from a prospectively maintained institutional database consisting of patients with stage I-III, HR-positive ILC who underwent surgical treatment between 1996 and 2019.

Results

Contrary to our expectations, we found that lower BMI was significantly associated with having higher Oncotype RS (18.9% versus 4.8%, p = 0.028) in post-menopausal patients, but was not related to tumor characteristics in pre-menopausal patients. Multivariate network analyses suggested a strong relationship between post-menopausal status itself and tumor characteristics, with lesser influence of BMI.

Conclusion

These findings provide further insight into the recently appreciated heterogeneity within ILC and support the need for further investigation into the drivers of this disease and tailored treatment strategies.

Decreased enrollment in breast cancer trials by histologic subtype: does invasive lobular carcinoma resist RECIST?

Enrollment in metastatic breast cancer trials usually requires measurable lesions, but patients with invasive lobular carcinoma (ILC) tend to form diffuse disease. We found that the proportion of patients with metastatic ILC enrolled in clinical trials at our institution was significantly lower than that of patients with invasive ductal carcinoma (IDC). Possible links between requiring measurable disease and decreased enrollment of ILC patients require further study to ensure equitable trial access.

Ganitumab and metformin plus standard neoadjuvant therapy in stage 2/3 breast cancer

I-SPY2 is an adaptively randomized phase 2 clinical trial evaluating novel agents in combination with standard-of-care paclitaxel followed by doxorubicin and cyclophosphamide in the neoadjuvant treatment of breast cancer. Ganitumab is a monoclonal antibody designed to bind and inhibit function of the type I insulin-like growth factor receptor (IGF-1R). Ganitumab was tested in combination with metformin and paclitaxel (PGM) followed by AC compared to standard-of-care alone. While pathologic complete response (pCR) rates were numerically higher in the PGM treatment arm for hormone receptor-negative, HER2-negative breast cancer (32% versus 21%), this small increase did not meet I-SPY's prespecified threshold for graduation. PGM was associated with increased hyperglycemia and elevated hemoglobin A1c (HbA1c), despite the use of metformin in combination with ganitumab. We evaluated several putative predictive biomarkers of ganitumab response (e.g., IGF-1 ligand score, IGF-1R signature, IGFBP5 expression, baseline HbA1c). None were specific predictors of response to PGM, although several signatures were associated with pCR in both arms. Any further development of anti-IGF-1R therapy will require better control of anti-IGF-1R drug-induced hyperglycemia and the development of more predictive biomarkers.

A world-wide survey on kidney transplantation practices in breast cancer survivors: The need for new management guidelines

Kidney transplantation reduces mortality in patients with end stage renal disease (ESRD). Decisions about performing kidney transplantation in the setting of a prior cancer are challenging, as cancer recurrence in the setting of immunosuppression can result in poor outcomes. For cancer of the breast, rapid advances in molecular characterization have allowed improved prognostication, which is not reflected in current guidelines. We developed a 19-question survey to determine transplant surgeons' knowledge, practice, and attitudes regarding guidelines for kidney transplantation in women with breast cancer. Of the 129 respondents from 32 states and 14 countries, 74.8% felt that current guidelines are inadequate. Surgeons outside the United States (US) were more likely to consider transplantation in a breast cancer patient without a waiting period (p = .017). Within the US, 29.2% of surgeons in the Western region would consider transplantation without a waiting period, versus 3.6% of surgeons in the East (p = .004). Encouragingly, 90.4% of providers surveyed would consider eliminating wait-times for women with a low risk of cancer recurrence based on the accurate prediction of molecular assays. These findings support the need for new guidelines incorporating individualized recurrence risk to improve care of ESRD patients with breast cancer.

Positive margins after mastectomy in patients with invasive lobular carcinoma of the breast: Incidence and management strategies

BACKGROUND

Surgical treatment of invasive lobular carcinoma (ILC) is challenging due to its diffuse growth pattern, and the positive margin rate after mastectomy is poorly described.

METHODS

We retrospectively determined the positive margin rate in those with stage I-III ILC undergoing mastectomy. We evaluated the relationship between management strategy and recurrence free survival (RFS).

RESULTS

In 357 patients, the positive margin rate was 10.6% overall and 18.7% in those with T3 tumors. Having a positive margin was associated with significantly shorter RFS on multivariate analysis (p = 0.01). Undergoing additional local treatment (radiation or re-excision) for a positive margin was significantly associated with improved RFS (p = 0.004). Older women with positive margins were significantly less likely to undergo additional local therapy.

CONCLUSIONS

Even mastectomy fails to clear margins in a high proportion of patients with large ILC tumors, a finding which may warrant testing neoadjuvant strategies even prior to planned mastectomy.

Decreased enrollment of patients with advanced lobular breast cancer compared to ductal breast cancer in interventional clinical trials

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Background: Response Evaluation Criteria in Solid Tumors (RECIST) criteria are often used to measure tumor response in cancer trials, especially in the stage IV setting. However, RECIST requires measurable disease, which is less common in invasive lobular breast carcinoma (ILC) of the breast, a diffusely growing tumor type, compared to invasive ductal carcinoma (IDC). We examined the prevalence of RECIST in breast cancer clinical trials, and whether there are differential trial enrollment rates by histology and stage. Methods: We analyzed the clinicaltrials.gov database to evaluate the proportion of interventional, stage IV clinical trials that require measurable disease as inclusion criteria or outcome measures. We then performed an institutional cohort study comparing the proportion of patients in the University of California, San Francisco (UCSF) OnCore clinical trials management system (CTMS) to the UCSF Cancer Registry between 2000-2018, stratified by histology and stage. We hypothesized that the proportion of patients with ILC in the CTMS would be significantly lower than in the cancer registry. Results: There were 146 actively-recruiting, interventional clinical trials for stage IV breast cancer that were identified in our search on clinicaltrials.gov. Overall, 108 (74%) required measurable disease for study participation. The UCSF Cancer Registry included 8,679 patients, while the UCSF OnCore CTMS included 1,511 patients (Table). In those with early stage disease, where RECIST is not typically used, there was no difference in the proportion of ILC patients enrolled in clinical trials versus in the cancer registry. However, among those with stage IV disease, there was a significantly lower proportion of patients with ILC in the CTMS than in the cancer registry (9.2% versus 17.9%, p = 0.005). In contrast, patients with stage IV IDC were overrepresented in the clinical trials database compared to the cancer registry. Conclusions: Patients with metastatic ILC were significantly less likely to be enrolled in clinical trials than those with metastatic IDC. This decreased enrollment may be due to the widespread use of RECIST, and further investigation is needed to ensure equity in access to clinical trials.[Table: see text]

Early onset, multiple, bilateral fibroadenomas of the breast: a case report

BACKGROUND

While fibroadenomas are common in the general population, affecting 10-20% of women, they are rarely early-onset, multiple, and bilateral.

CASE PRESENTATION

An 18-year-old woman presented with a 6 year history of multiple, bilateral breast masses without family history of breast disease. Magnetic resonance imaging (MRI, Fig. 1) of the breasts showed innumerable, bilateral breast masses ranging in size from 0.5 to 4 cm. Two needle biopsies showed fibroadenoma. Although the patient's family history did not meet National Comprehensive Cancer Network (NCCN) guidelines for genetic testing, it was performed due to the rarity of her presentation. Genetic testing identified a pathogenic mutation in the phosphatase and tensin homolog (PTEN) gene.

CONCLUSIONS

A germline mutation in PTEN is associated with an increased risk of breast cancer and often occurs as part of Cowden Syndrome. This case highlights the importance of genetic testing in patients with unusual presentations of early-onset, bilateral, and multiple (greater than four) fibroadenomas.

Relationship between body mass index and malignancy rates of MRI-guided breast biopsies: impact of clinicodemographic factors

PURPOSE

To determine the positive predictive value (PPV) of magnetic resonance imaging (MRI)-guided breast biopsy stratified by body mass index (BMI). Secondary endpoints include evaluation of indications for breast MRI and identification of factors associated with malignant biopsy.

METHODS

We retrospectively analyzed results of MRI-guided breast biopsies in a consecutive cohort of women at a single institution between 2014 and 2019. The PPV was compared between BMI subgroups and the overall group by the one-sample z-test. Factors associated with malignant biopsy were analyzed using multivariate regression analysis.

RESULTS

Among 427 MRI-guided breast biopsies, the PPV was significantly higher in patients with a BMI ≥ 35 compared to BMI < 35 (38.6% versus 24.5%, p = 0.043). This remained true in the 180 biopsies from high-risk screening studies, but there was no difference in PPV by BMI in the 205 biopsies performed to evaluate extent of known disease. Among this cohort who underwent MRI-guided breast biopsy, the underlying indication for MRI was less likely to be high-risk screening in those with a higher BMI or Black or Hispanic race (p = 0.015 and p < 0.001, respectively). For high-risk screening studies, only BMI ≥ 35 was associated with malignant biopsies (OR 37.5, p = 0.003). For evaluation of extent of disease studies, only increased lesion size was a significant predictor of malignant result (OR 1.01, p = 0.04).

CONCLUSIONS

Among women who underwent MRI-guided breast biopsy, elevated BMI was associated with increased PPV and malignant biopsies. Patients with a higher BMI or Black or Hispanic race who had MRI-guided biopsy were less likely to be undergoing high-risk screening and more likely to have breast MRI to evaluate extent of known disease.

Changes in Management Strategy and Impact of Neoadjuvant Therapy on Extent of Surgery in Invasive Lobular Carcinoma of the Breast: Analysis of the National Cancer Database (NCDB)

Background

Given reports of low response rates to neoadjuvant chemotherapy (NAC) in invasive lobular carcinoma (ILC), we evaluated whether use of alternative strategies such as neoadjuvant endocrine therapy (NET) is increasing. Additionally, we investigated whether NET is associated with more breast conservation surgery (BCS) and less extensive axillary surgery in those with ILC.

Patients and Methods

We queried the NCDB from 2010 to 2016 and identified all women with stage I–III hormone receptor positive, human epidermal growth factor receptor-2 negative (HR+/HER2−) ILC who underwent surgery. We used Cochrane–Armitage tests to evaluate trends in utilization of the following treatment strategies: NAC, short-course NET, long-course NET, and primary surgery. We compared rates of BCS and extent of axillary surgery stratified by clinical stage and tumor receptor subtype for each treatment strategy.

Results

Among 69,312 cases of HR+/HER2− ILC, NAC use decreased slightly (from 4.7 to 4.2%, p = 0.007), while there was a small but significant increase in long-course NET (from 1.6 to 2.7%, p < 0.001). Long-course NET was significantly associated with increased BCS in patients with cT2–cT4 disease and less extensive axillary surgery in clinically node positive patients with HR+/HER2− tumors.

Conclusions

Primary surgery remains the most common treatment strategy in patients with ILC. However, NAC use decreased slightly over the study period, while the use of long-course NET had a small increase and was associated with more BCS and less extensive axillary surgery.

Stiff stroma increases breast cancer risk by inducing the oncogene ZNF217

Women with dense breasts have an increased lifetime risk of malignancy that has been attributed to a higher epithelial density. Quantitative proteomics, collagen analysis, and mechanical measurements in normal tissue revealed that stroma in the high-density breast contains more oriented, fibrillar collagen that is stiffer and correlates with higher epithelial cell density. microRNA (miR) profiling of breast tissue identified miR-203 as a matrix stiffness-repressed transcript that is downregulated by collagen density and reduced in the breast epithelium of women with high mammographic density. Culture studies demonstrated that ZNF217 mediates a matrix stiffness- and collagen density-induced increase in Akt activity and mammary epithelial cell proliferation. Manipulation of the epithelium in a mouse model of mammographic density supported a causal relationship between stromal stiffness, reduced miR-203, higher levels of the murine homolog Zfp217, and increased Akt activity and mammary epithelial proliferation. ZNF217 was also increased in the normal breast epithelium of women with high mammographic density, correlated positively with epithelial proliferation and density, and inversely with miR-203. The findings identify ZNF217 as a potential target toward which preexisting therapies, such as the Akt inhibitor triciribine, could be used as a chemopreventive agent to reduce cancer risk in women with high mammographic density.

Contralateral prophylactic mastectomy: A narrative review of the evidence and acceptability

The uptake of contralateral prophylactic mastectomy (CPM) has increased steadily over the last twenty years in women of all age groups and breast cancer stages. Since contralateral breast cancer is relatively rare and the breast cancer guidelines only recommend CPM in a small subset of patients with breast cancer, the drivers of this trend are unknown. This review aims to evaluate the evidence for and acceptability of CPM, data on patient rationales for choosing CPM, and some of the factors that might impact patient preferences. Based on the evidence, future recommendations will be provided. First, data on contralateral breast cancer risk and CPM rates and trends are addressed. After that, the evidence is structured around four main patient rationales for CPM formulated as questions that patients might ask their surgeon: Will CPM reduce mortality risk? Will CPM reduce the risk of contralateral breast cancer? Can I avoid future screening with CPM? Will I have better breast symmetry after CPM? Also, three different guidelines regarding CPM will be reviewed. Studies indicate a large gap between patient preferences for radical risk reduction with CPM and the current approaches recommended by important guidelines. We suggest a strategy including shared decision-making to enhance surgeons’ communication with patients about contralateral breast cancer and treatment options, to empower patients in order to optimize the use of CPM incorporating accurate risk assessment and individual patient preferences.

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Contralateral prophylactic mastectomy rates have increased over the last 20 years.

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Patients may want CPM to reduce risk of contralateral breast cancer and mortality.

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Patients do not always have the tools available to make a well-informed decision.

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Patient and surgeon’s shared decision-making could optimize the use of CPM.

Oncological Outcomes of Total Skin-Sparing Mastectomy for Invasive Lobular Carcinoma of the Breast: A 20-Year Institutional Experience

BACKGROUND

Although rates of total skin-sparing (nipple-sparing) mastectomies are increasing, the oncologic safety of this procedure has not been evaluated in invasive lobular carcinoma (ILC). ILC is the second most common type of breast cancer, and its diffuse growth pattern and high positive margin rates potentially increase the risk of poor outcomes from less extensive surgical resection.

METHODS

We compared time to local recurrence and positive margin rates in a cohort of 300 patients with ILC undergoing either total skin-sparing mastectomy (TSSM), skin-sparing mastectomy, or simple mastectomy between the years 2000-2020. Data were obtained from a prospectively maintained institutional database and were analyzed by using univariate statistics, the log-rank test, and multivariate Cox proportional hazards models.

RESULTS

Of 300 cases, mastectomy type was TSSM in 119 (39.7%), skin-sparing mastectomy in 52 (17.3%), and simple mastectomy in 129 (43%). The rate of TSSM increased significantly with time (p < 0.001) and was associated with younger age at diagnosis (p = 0.0007). There was no difference in time to local recurrence on univariate and multivariate analysis, nor difference in positive margin rates by mastectomy type. Factors significantly associated with shorter local recurrence-free survival were higher tumor stage and tumor grade.

CONCLUSIONS

TSSM can be safely offered to patients with ILC, despite the diffuse growth pattern seen in this tumor type.

Breast conservation therapy versus mastectomy in the surgical management of invasive lobular carcinoma measuring 4 cm or greater

BACKGROUND

The safety of breast conservation therapy (BCT) has not been demonstrated in large ILC tumors, potentially contributing to the higher mastectomy rates seen in ILC.

METHODS

We queried a prospectively maintained database to identify patients with ILC measuring ≥4 cm and evaluated difference in recurrence free survival (RFS) between those treated with BCT versus mastectomy using a multivariate model.

RESULTS

Of 180 patients, 30 (16.7%) underwent BCT and 150 (83.3%) underwent mastectomy. Patients undergoing mastectomy were younger (56.6 vs. 64.3 years, p = 0.003) and had larger tumors (7.2 vs. 5.4 cm, p < 0.001). While tumor size, nodal stage, receptor subtype, and margin status were significantly associated with RFS, there was no difference in RFS at 5 (p = 0.88) or 10 (p = 0.65) years for individuals undergoing BCT versus mastectomy.

CONCLUSIONS

For patients with ILC ≥4 cm, BCT provides similar tumor control as mastectomy, provided that negative margins are achieved.

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.