Lynch Syndrome and Breast Cancer Risk: Weighing the Data

Contralateral lymph node metastasis in recurrent ipsilateral breast cancer with Lynch syndrome: a locoregional event

INTRODUCTION

Contralateral axillary lymph node metastasis (CALNM) in breast cancer (BC) is considered a distant metastasis, marking stage 4cancer. Therefore, it is generally treated as an incurable disease. However, in clinical practice, staging and treatment remain controversial due to a paucity of data, and the St. Gallen 2021 consensus panel recommended a curative approach in patients with oligometastatic disease. Aberrant lymph node (LN) drainage following previous surgery or radiotherapy is common. Therefore, CALNM may be considered a regional event rather than systemic disease, and a re-sentinel procedure aided by lymphoscintigraphy permits adequate regional staging.

CASE REPORT

Here, we report a 37-year-old patient with Lynch syndrome who presented with CALNM in an ipsilateral relapse of a moderately differentiated invasive ductal BC (ER 90%, PR 30%, HER2 negative, Ki-67 25%, microsatellite stable), 3 years after the initial diagnosis. Lymphoscintigraphy detected a positive sentinel LN in the contralateral axilla despite no sign of LN involvement or distant metastases on FDG PET/CT or MRI. The patient underwent bilateral mastectomy with sentinel node dissection, surgical reconstruction with histological confirmation of the CALNM, left axillary dissection, adjuvant chemotherapy, and anti-hormone therapy. In addition to her regular BC follow-up visits, the patient will undergo annual colonoscopy, gastroscopy, abdominal, and vaginal ultrasound screening. In January 2023, the patient was free of progression for 23 months after initiation of treatment for recurrent BC and CALNM.

CONCLUSION

This case highlights the value of delayed lymphoscintigraphy and the contribution of sentinel procedure for local control in the setting of recurrent BC. Aberrant lymph node drainage following previous surgery may be the underlying cause of CALNM. We propose that CALNM without evidence of systemic metastasis should be considered a regional event in recurrent BC, and thus, a curative approach can be pursued. The next AJCC BC staging should clarify the role of CALNM in recurrent BC to allow for the development of specific treatment guidelines.

Double heterozygous pathogenic variants prevalence in a cohort of patients with hereditary breast cancer

Hereditary breast cancer (BC) corresponds to 5% of all BC and a larger parcel of early-onset disease. The incorporation of next-generation sequencing (NGS) techniques reduced the cost of molecular testing and allowed the inclusion of additional cancer predisposition genes in panels that are more comprehensive. This enabled the identification of germline pathogenic variants in carriers and the introduction of risk-reducing strategies. It also resulted in the identification of the co-occurrence of more than one germline pathogenic variant in BC genes in some families. This is a rare event, and there are few reports on its impact on cancer risk. We conducted a single-institution retrospective study in which 1,156 women with early onset BC and/or a family history of cancer were tested by a germline multi-gene hereditary cancer panel. Germline pathogenic variants in high- and/or moderate-penetrance BC genes were identified in 19.5% of the individuals (n = 226). The most frequent variants were found in TP53 (69 of 226; 55 of them represented by p.R337H), BRCA1 (47 of 226), and BRCA2 (41 of 226). Double heterozygous (DH) variants were detected in 14 cases, representing 1.2% of all individuals assessed. There were no significant differences in age of BC onset and risk for bilateral BC in DH carriers when compared with those with one germline variant.

How Have Multigene Panels Changed the Clinical Practice of Genetic Counseling and Testing

Historically, genetic testing (and billing) for hereditary cancer risk was essentially performed gene by gene, with clinicians ordering testing only for the genes most likely to explain a patient's or family's cancer presentation, with laboratories typically charging $1,000 to $1,500 for each gene that was sequenced. Given the expense, only patients at high risk of having a hereditary syndrome were offered testing. With the introduction of next-generation sequencing technologies, however, laboratories are able to test for multiple genes at the same time with greater efficiency, significantly decreased costs, and relatively little increased expense when adding additional genes. This has drastically altered clinical practice so that clinicians now typically order testing for a panel of multiple genes for most patients. Although this approach has streamlined the diagnostic odyssey, it has introduced several problems, as well, including difficulties in choosing the appropriate panel test for a given patient, assessing the significance of identified genetic variants (including variants of uncertain significance [VUS]), and understanding the disease risks and management associated with pathogenic variants in a given gene. Many laboratories offer testing for genes that have limited data supporting their associated cancer risks, which then leads to an inability to set management guidelines based on that gene. In addition, testing larger numbers of genes increases the likelihood of finding one or more VUS, which introduce their own management issues. Thus, although panel testing has certainly moved clinical practice forward in many ways, it has also raised its own set of problems that increase the complexity of genetic counseling and highlight the need for education of community practitioners on the complexities and nuances of this testing. Whenever possible, testing should be performed by, or in consultation with, cancer genetics professionals.