Literature review on the bilateral occurrence of invasive lobular breast cancer.

Historically, it has been believed that invasive lobular carcinomas (ILC) occur more frequently bilaterally compared to other invasive subtypes, with estimates ranging between 20% and 29%. This study aims to determine if this historical perspective still holds true. A comprehensive literature review was conducted to examine the bilateral occurrence of lobular carcinoma using various imaging methods. Additionally, the role of magnetic resonance imaging (MRI) in detecting contralateral carcinomas was also investigated. A comprehensive search was conducted in the MedLine database on the PubMed platform, resulting in 307 articles published between January 1, 2014, and January 1, 2023. Various selection criteria were applied to identify articles relevant to the research question. After careful assessment, eight articles remained that met the eligibility criteria, all of which provided level-three evidence and were therefore included in the literature review. A total of 599 patients were included in this review, comprising a total of 602 cases of ILC. Six out of the eight articles reviewed provided information on the bilateral occurrence of ILC based on histopathology. A weighted average calculation yielded a bilaterality percentage of 4.95% (24 out of 485 cases). Four articles reported the number of bilateral cases identified through MRI, resulting in a weighted average of 10.2% (26 out of 255 cases). It is worth noting that 20.4% (100 out of 491) of the performed MRIs were found to be either useless or even harmful. Furthermore, MRI led to a change in the treatment plan in 27.7% (136 out of 491) of cases. Overall, it can be concluded that there is limited available data regarding the bilateral occurrence of ILC. The numbers found in the literature are also inconsistent and tend to vary. The literature review revealed a decrease in the percentage of bilaterality compared to historical beliefs. Based on this study, it can be concluded that a high number of MRI scans were found to be either useless or harmful. As a result of this conclusion and a higher sensitivity of other screening modalities, MRI may no longer be indicated as part of the standard workup for ILC. However, further research is necessary to validate these findings.

Retrospective cohort study on the bilateral occurrence of invasive lobular breast cancer.

OBJECTIVE: Invasive lobular carcinoma (ILC) is the second most common histological subtype of invasive breast cancer, following the no special type (NST) invasive carcinoma. It has historically been assumed that ILC occurs bilaterally in 20-29 % of cases, which has influenced the inclusion of MRI in the standard workup of ILC according to European guidelines. However, challenging this long-held belief regarding the bilateral occurrence of ILC opens up the possibility of revising the guidelines and using MRI only for more specific indications. This study aims to evaluate whether the previously reported high percentage of bilaterality still holds true and to question the added value of MRI in the standard workup of ILC. STUDY DESIGN: A retrospective cohort study was conducted following approval from the institutional review board (EC 21/18/249) at Antwerp University Hospital (UZA). The cohort comprised female patients of all ages who had been diagnosed with either ILC or NST invasive carcinoma and had sought consultation at the UZA breast clinic. A comprehensive database was established to collect information on patient characteristics, imaging, and pathology. RESULTS: A total of 271 patients with ILC were included in the study, with incidence dates ranging from 01/01/2007 to 01/01/2023. Among these patients, a synchronous bilateral ILC lesion was observed in 1.85 % (5/271) of cases. This proportion is significantly lower than the reported percentage of patients with a bilateral lesion in the literature population, which stands at 4.95 %. The reference group consisted of 809 patients with NST invasive carcinoma, with incidence dates ranging from 01/01/2017 to 01/01/2023. In the control group, a synchronous bilateral NST lesion was observed in 3.96 % (32/809) of cases. There is no significant difference in the bilaterality rates between the group of ILC patients and the group of NST patients. Furthermore, MRI did not detect any histopathologically confirmed contralateral ILC lesion that had not already been detected by mammography or ultrasound. CONCLUSIONS: The study results indicate a lower occurrence of bilateral ILC than previously assumed. Additionally, the incidence of synchronous bilateral lesions in ILC patients is not higher compared to patients with NST invasive carcinoma. Performing an MRI does not provide additional value in detecting bilateral carcinomas in ILC. Consequently, it is recommended that the current European guidelines be reassessed, and the indications for undergoing an MRI should be adjusted accordingly.