Abstract PS7-81: Clinical and pathological features of very early-onset breast cancer and treatment challenges on public health care system at a cancer center in Brazil
Authors: Caldas Natasha Garcia , Souza Karoline Evangelista , Vivan Thais Karla , Santana Vinicius Xavier , Passos Mauro Pinto , Polidorio Natalia 
Published: February 2021

Abstract
Background: Even though breast cancer is uncommon in women ≤ age 35, women in this group are more likely to present aggressive cancer subtypes, advanced clinical stage at diagnosis and pathogenic variants (PV) in cancer susceptibility genes. Higher recurrence and mortality rates in very early-onset breast cancer patients may be related to differences in tumor biology, mutation status, clinical or treatment features. Management of those women should comprehend dedicated approach and standard care that are often not available on cancer care centers at low-middle income countries. We aim to describe the clinical and pathological factors associated with very early-onset breast cancer patients and the challenges associated with treatment of those women in a public health facility in Brazil. Methods: Retrospective review of 748 patients diagnosed and treated at the biggest surgical center for breast cancer in Brasilia - Brazil between 2015 and 2020 was performed and 54 patients with cancer diagnosis ≤ age 35 were identified. Pathological and clinical characteristics as well as treatment information were collected from medical and electronic patients’ records. Bivariate and multivariate analyzes were performed. Findings: Median age at diagnosis was 31.9 years old (23 to 35). 44% had a positive familial history for HBOC. 20% presented first period &lt;12 years of age and 61% and 53% had first childbirth &lt; 30 years and breastfed for over 6 months, respectively. Only 10% had a BMI index over 30, and 37% were overweight. The distribution of BC stage at diagnosis was I (9.3%), II (51.9%), III (29.6%) and IV (3.7%). The most common were invasive carcinoma of no special type (98%) and malignant phyllodes (2%) and 10.9%, 50.9% and 27.3% were grades 1, 2 and 3, respectively. BC subtypes were as follows: Luminal A 18.5%, Luminal B 31.5%, HER2 positive 24.1% and Triple negative 25.9%. With a mean follow-up of 31.94 months, the overall survival rate was 93%, with a recurrence-free survival rate of 72.1%.Although all patients met the criteria for germline testing, only 25.9% had access, with two BRCA1, four BRCA 2, one CHECK2 and one TP53 PV detected. 27.8% had BCS as surgical treatment and 53.7% e 13% had unilateral and bilateral mastectomy. There was an increased rate of bilateral mastectomy on the last 8 years. 73.6% were treated with neoadjuvant chemotherapy (NC) and mean interval between NC and surgery was 61.1 days (19-370). 63% had radiotherapy and the mean interval between previous treatment (chemotherapy or surgery) and radiotherapy was 93.8 days (56-150). None of the HER2 positive patients were exposed to dual HER2 blockade and there was no adjuvant treatment with T-DM1 or capecitabine when pCR was not achieved. Only 22% of the women with hormone receptor tumors were exposed to ovarian suppression alongside hormone therapy. Of the 54 patients, 27.9% relapsed, 18.6% distant recurrence, 9.3% local. The most common sites of metastasis was bone and liver (6.8% each) followed by lung and central nervous system (3.4% and 1.7%). Conclusions: Previous studies showed that breast cancer is diagnosed at an earlier age among Brazilian patients. BC is often detected when symptomatic and therefore a significant proportion is diagnosed at more advanced clinical stages. These findings alongside the restrict acess to genetic counseling and the delay on treatment in the public healthcare system are a clear indication of the challenges for achieving standard care for those patients and could have a significant impact on survival outcomes. These data combined indicate the need for supportive care program for young women with breast cancer.
Citation Format: Natasha Garcia Caldas, Karoline Evangelista Souza, Thais Karla Vivan, Vinicius Xavier Santana, Mauro Pinto Passos, Natalia Polidorio. Clinical and pathological features of very early-onset breast cancer and treatment challenges on public health care system at a cancer center in Brazil [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-81.