Founder mutations BRCA2 c.156_157insAlu in Portuguese population

Date 03 May 2019
Event ESMO Breast Cancer 2019
Session Poster lunch
Topics Aetiology, Epidemiology, Screening and Prevention
Breast Cancer
Hereditary Syndromes
Presenter Filipa Macedo
Citation Annals of Oncology (2019) 30 (suppl_3): iii1-iii26. 10.1093/annonc/mdz095
Authors F. Macedo, R. Félix Soares, T. Cunha Pereira, A.R. Monteiro, N. Bonito, S. Broco, T. Carvalho, M. Mariano, G. Sousa
  • Medical Oncology, Portuguese Oncology Institute of Coimbra, 3000-075 - Coimbra/PT

Abstract

Background

Inherited predisposition to breast cancer (BC) accounts for about 5–10% of all cases. Women carrying germline BRCA2 mutations have a cumulative risk at 70 years of 55% for BC and 17% for ovarian cancer. The c.156_157insAlu BRCA2 mutation has so far only been reported in hereditary breast/ovarian cancer families of Portuguese origin.

Methods

The authors collected information about every family with the c.156_157insAlu BRCA2 mutation followed in our center. The objective of this study is to divulge this mutation among European community, since this mutation is not detectable using the commonly used screening methodologies and must be specifically sought out.

Results

It was identified 27 patients with the mutation, and 51 healthy mutations carriers. All the subjects are natural from the central Portugal. The patients were mainly women (85%), younger than 50 years old at diagnosis (M = 44; SD = 13). Two patients (7.4%) had ovarian cancer, 4 patients (14.8%) had bilateral BC at diagnosis and 9 patients (33.3%) had second cancers some years later (breast, prostate, colorectal and skin). From every BC diagnosed, 55.2% were luminal B like, 24.1% were luminal A like, 6.9% were luminal B Her 2 and 13.8% were triple negative. None of the patients were a stage IV at diagnosis but 30% had metastization during the surveillance time, 24.1% were stage I, 44.8% stage II, and 31.0% stage III. Neoadjuvant chemotherapy was performed in 40% of the patients, with only 2 patients having complete response and 2 patients with no response at all. Adjuvant chemotherapy was prescribed in 53.3%, and palliative treatment in 30%. From the metastasized patients, 66.7% had more than one organ affected, and 66.7% had more than 1 palliative treatment. Presently, 26.9% of the patients are dead. The five-year survival rate is 92.6%. Only 30% of the patients agreed to perform prophylactic surgeries. No relation was found between the age of diagnosis and the clinical stage, the metastization, the chance of a second tumor, and death (p > 0,05).

Conclusions

The authors aimed to sensitize physicians regarding the extension of screening of the c.156_157insAlu mutation to all high-risk breast/ovarian cancer families with Portuguese ancestry since these patients will have a different follow-up due to their chance to have second tumors.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Filipa Macedo.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.