Papillary breast cancer: therapeutic and prognostic real-world data on a rare histologic type

Abstract

Introduction: Papillary carcinoma is classified as a special subtype of breast neoplasm with an estimated incidence of 0.5% to 1.7% of all invasive breast carcinomas. Due to its rarity, treatment for these tumors is generally based on extrapolation from data on non-special tumor types. Objective: This study aimed to describe the epidemiological, therapeutic, and prognostic characteristics of patients with papillary carcinoma treated at an oncology center in the city of São Paulo. Methods: In this retrospective cohort, patients with histopathological confirmation of invasive papillary breast carcinoma diagnosed at the Cancer Institute of the State of São Paulo between 2008 and 2022 were included. Data were collected from the medical records of patients treated at the institution. In situ papillary carcinomas were excluded. The variables analyzed included demographic data, tumor characteristics, types of therapies administered, and survival outcomes. Results: A total of 121 cases were identified. The median age was 66 years, with a predominance of white patients (68.1%), postmenopausal women (82.2%), early-stage disease (clinical stage I: 28.1%; clinical stage II: 66.9%), and early tumors (T1: 28.9%; T2: 53.7%; N0: 50.4%). There was a higher prevalence of hormone receptor–positive tumors (Luminal A: 24.4%; Luminal B: 51.3%) and histological grade II tumors (53.3%). All patients underwent surgery, with most receiving adjuvant chemotherapy (59.1%) and radiotherapy (66.4%). The mean follow-up time was 5.1 years, with 85.1% of patients alive and without evidence of disease at five years. Conclusion: This study contributes to characterizing, in a real-world setting, the clinical behavior and prognosis of papillary breast carcinoma. The high 5-year recurrence-free survival indicates a favorable prognosis for this histological type. This information may, in the future, help guide more individualized treatment and follow-up strategies, with the potential to improve long-term outcomes for these patients.