Synchronous bilateral breast cancer: a nationwide study on histopathology and etiology

Tumor Characteristics of Bilateral Breast Cancer Compared with Unilateral Breast Cancer

BACKGROUND

Bilateral breast cancer (BC) has an incidence of 1 to 3 %. This study aimed to describe the clinicopathologic characteristics and management of bilateral BC, estimate disease-free survival (DFS), and compare DFS with unilateral BC.

METHODS

A retrospective analysis was performed for patients who had bilateral invasive BC or unilateral invasive BC and contralateral ductal carcinoma in situ (DCIS) treated at Mayo Clinic Rochester from 2008 to 2022. A 4:1 matched cohort of patients with unilateral invasive BC was used for comparison. The groups were compared using Wilcoxon rank-sum or chi-square tests. Disease-free survival was analyzed using the Kaplan-Meier method and log-rank test, with Cox proportional hazards regression used for multivariable analysis.

RESULTS

The study identified 278 cases of bilateral breast cancer (177 cases of bilateral invasive cancer and 101 cases of unilateral invasive cancer with contralateral DCIS), representing 4.1 % of invasive BCs. Biologic subtype was concordant between sides in 79.8 % of the patients. Initial surgery was bilateral mastectomy for 76.6 %, bilateral lumpectomy for 20.5 %, and unilateral mastectomy with unilateral lumpectomy for 2.9 % of the patients. Pathogenic variants in breast cancer predisposition genes were present in 21.7 % of those tested. The patients who had bilateral BC presented with a higher cT category than the patients who had unilateral BC (p = 0.02), and a higher proportion presented with ILC (17.3 % vs 10.9 %; p = 0.004), estrogen receptor-positive (ER+) disease (89.2 % vs 84.2 %; p = 0.04), multicentric/multifocal disease (37.1 % vs 24.3 %; p < 0.001), breast cancer pathogenic variant (21.7 % vs 12.4 %; p = 0.02), and palpable presentation (48.2 % vs 40.8 %; p = 0.03). The patients with bilateral BC showed DFS similar to that for the unilateral BC cohort (p = 0.71).

CONCLUSIONS

Bilateral BCs most commonly are biologically concordant between sides. Bilateral BC presented more commonly with larger tumors, lobular histology, ER+ status, multicentricity or multifocality, pathogenic variant, and palpable disease. Bilateral BC is not associated with worse DFS than unilateral BC.

A study of clinical and molecular characteristics in bilateral primary breast cancer

BACKGROUND

Bilateral primary breast cancer (BPBC) is a rare type of breast cancer. Studies on the clinicopathologic and molecular characteristics of BPBC in a metastatic context are very limited.

METHODS

A total of 574 unselected metastatic breast cancer patients with clinical information were enrolled in our next-generation sequencing (NGS) database. Patients with BPBC from our NGS database were regarded as the study cohort. In addition, 1467 patients with BPBC and 2874 patients with unilateral breast cancer (UBC) from the Surveillance, Epidemiology, and End Results (SEER) public database were also analyzed to determine the characteristics of BPBC.

RESULTS

Among the 574 patients enrolled in our NGS database, 20 (3.5%) patients had bilateral disease, comprising 15 (75%) patients with synchronous bilateral disease and 5 (25%) patients with metachronous bilateral disease. Eight patients had bilateral hormone receptor-positive (HR+)/human epidermal growth factor receptor-negative (HER2-) tumors, and three had unilateral HR+/HER2- tumors. More HR+/HER2- tumors and lobular components were found in BPBC patients than in UBC patients. The molecular subtype of the metastatic lesions in three patients was inconsistent with either side of the primary lesions, which suggested the importance of rebiopsy. Strong correlations in clinicopathologic features between the left and right tumors in BPBC were exhibited in the SEER database. In our NGS database, only one BPBC patient was found with a pathogenic germline mutation in BRCA2. The top mutated somatic genes in BPBC patients were similar to those in UBC patients, including TP53 (58.8% in BPBC and 60.6% in UBC) and PI3KCA (47.1% in BPBC and 35.9% in UBC).

CONCLUSIONS

Our study suggested that BPBC may tend to be lobular carcinoma and have the HR+/HER2- subtype. Although our study did not find specific germline and somatic mutations in BPBC, more research is needed for verification.

Intraoperative electron radiotherapy in early invasive ductal breast cancer: 6-year median follow-up results of a prospective monocentric registry

Background

Intraoperative electron radiotherapy (IOERT) can be used to treat early breast cancer during the conservative surgery thus enabling shorter overall treatment times and reduced irradiation of organs at risk. We report on our first 996 patients enrolled prospectively in a registry trial.

Methods

At Jules Bordet Institute, from February 2010 onwards, patients underwent partial IOERT of the breast. Women with unifocal invasive ductal carcinoma, aged 40 years or older, with a clinical tumour size ≤ 20 mm and tumour-free sentinel lymph node (on frozen section and immunohistochemical analysis). A 21 Gy dose was prescribed on the 90% isodose line in the tumour bed with the energy of 6 to 12 MeV (Mobetron®-IntraOp Medical).

Results

Thirty-seven ipsilateral tumour relapses occurred. Sixteen of those were in the same breast quadrant. Sixty patients died, and among those, 12 deaths were due to breast cancer. With 71.9 months of median follow-up, the 5-year Kaplan–Meier estimate of local recurrence was 2.7%.

Conclusions

The rate of breast cancer local recurrence after IOERT is low and comparable to published results for IORT and APBI. IOERT is highly operator-dependent, and appropriate applicator sizing according to tumour size is critical. When used in a selected patient population, IOERT achieves a good balance between tumour control and late radiotherapy-mediated toxicity morbidity and mortality thanks to insignificant irradiation of organs at risk.

Current and future diagnostic and treatment strategies for patients with invasive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (ILC) is the second most common type of breast cancer after invasive breast cancer of no special type (NST), representing up to 15% of all breast cancers.

DESIGN

Latest data on ILC are presented, focusing on diagnosis, molecular make-up according to the European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets (ESCAT) guidelines, treatment in the early and metastatic setting and ILC-focused clinical trials.

RESULTS

At the imaging level, magnetic resonance imaging-based and novel positron emission tomography/computed tomography-based techniques can overcome the limitations of currently used imaging techniques for diagnosing ILC. At the pathology level, E-cadherin immunohistochemistry could help improving inter-pathologist agreement. The majority of patients with ILC do not seem to benefit as much from (neo-)adjuvant chemotherapy as patients with NST, although chemotherapy might be required in a subset of high-risk patients. No differences in treatment efficacy are seen for anti-human epidermal growth factor receptor 2 (HER2) therapies in the adjuvant setting and cyclin-dependent kinases 4 and 6 inhibitors in the metastatic setting. The clinical utility of the commercially available prognostic gene expression-based tests is unclear for patients with ILC. Several ESCAT alterations differ in frequency between ILC and NST. Germline BRCA1 and PALB2 alterations are less frequent in patients with ILC, while germline CDH1 (gene coding for E-cadherin) alterations are more frequent in patients with ILC. Somatic HER2 mutations are more frequent in ILC, especially in metastases (15% ILC versus 5% NST). A high tumour mutational burden, relevant for immune checkpoint inhibition, is more frequent in ILC metastases (16%) than in NST metastases (5%). Tumours with somatic inactivating CDH1 mutations may be vulnerable for treatment with ROS1 inhibitors, a concept currently investigated in early and metastatic ILC.

CONCLUSION

ILC is a unique malignancy based on its pathological and biological features leading to differences in diagnosis as well as in treatment response, resistance and targets as compared to NST.

Expression of Senescence and Apoptosis Biomarkers in Synchronous Bilateral Breast Cancer: A Case Report

Background: Synchronous bilateral breast cancer (SBBC) provides a special condition where two independent breast tumors are exposed to cancer pharmacotherapy within a uniform pharmacokinetic milieu. Both senescence and apoptosis are established responses to therapy; however, they have potentially variable contributions to the overall outcome of treatment, which are yet to be determined. Methods: In this report, we describe the clinicopathological picture of two SBBC cases that received standard anticancer treatment and assess their expression profile of several molecular hallmarks of senescence and apoptosis. Results: Our analysis identified that synchronous tumors have variable expression profiles of both senescence- and apoptosis-associated biomarkers, despite comparable pathological responses to neoadjuvant chemotherapy and current survival rates. Conclusions: Our results highlight the variable expression of senescence- and apoptosis-associated markers in breast tumors (despite the shared somatic genetic background) and invites a large-scale assessment of both senescence and apoptosis in breast cancer tissue in vivo and their contribution to the pathological response and overall survival.