282PIdentification of ultralow risk breast cancer patients (probable overdiagnosis)

• Published in: Annals of oncology Vol. 30; no. Supplement_5
• Main Authors: Casado, S Gamez, Gómez, M Bernal, Bermejo, A Campini, Perez, L Rodriguez, Quilez, A, Candenas, J Calvete, Bernal, G Martínez, Rodríguez, E Benítez, Baena-Canada, J M
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01-10-2019
• ISSN: 0923-7534; 1569-8041
• DOI: 10.1093/annonc/mdz240.105

Abstract
Background
The universalisation of mammographic screening has caused an increase in ultralow risk breast cancer diagnosis. Identifying subgroups with no events related to mortality due to breast cancer in the long term (overdiagnosis) may be useful so as not to subject them to unnecessary treatment (overtreatment).
Methods
New ultralow risk criteria are described by means of mammographic screening diagnosis, tumour palpability, tumour phenotype, and absence of axillary node involvement. We identified patients with no events related to breast cancer mortality through a descriptive, observational, and retrospective study.
Results
Among the 746 patients with stage I and IIA breast cancer attended between 1/1/2001 and 31/12/2014, 110 (14.75%) came from mammographic screening with non-palpable tumours. The median age was 58 years old (38-71). 88 (80%) were hormone receptor positive (HR+), 10 (9.10%) were triple negatives, and 11 (10%) were HER-2. The median follow-up was 10 years (3.5-17). Only 3 patients developed metastasis, there were no loco-regional recurrence, 7 showed second primary tumours, and there were 4 deaths, 2 due to breast cancer and 2 due to other reasons. Overall survival (OS) was 92.80%, disease-free survival (DFS) was 85.20%, and the distant metastasis-free interval (DMFI) was 95.60%. In 88 patients with HR+ tumours, OS was 95.7%, DFS was 86.50%, and DMFI was 96.30%. In 34 (38.60%) histological grade 1 HR+ tumours (probably Luminal A), and in 54 (61.40%) histological grade 2-3 HR+ tumours (probably Luminal B), OS was 93.80% and 96.90% (p = 0.669), DFS was 81.90% and 89.30% (p = 0.400), and DMFI was 100% and 94.40% (p = 0.307). In triple negatives, OS was 85.70%, DFS 77.10%, and DMFI was 100%. In subgroup HER-2, there were no events. In tumours smaller and larger than 1 cm, OS was 100% and 90.20% (p = 0.168), DFS was 93.20% and 84.10% (p = 0.742), and DMFI was 100% and 95.50% (p = 0.296).
Conclusions
Patients with non-palpable tumours detected in mammographic screening have an ultralow risk. The absence of events related to breast cancer mortality makes them candidates for overdiagnosis. De-escalation of treatment should be considered. The authors will incorporate genomic risk to optimise the identification of overdiagnosis.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.