Breast cancer is a heterogeneous disease, and the estrogen receptor (ER) remains the most important biomarker in breast oncology. Most guidelines set a positive expression threshold of 1% staining in immunohistochemistry (IHC) to define ER positivity. However, different expression levels may be associated with diverse degrees of sensitivity to endocrine therapy as ER expression may impact breast cancer molecular biology as a continuous variable. ER-lo tumors, defined as those with 1-10% ER expression, represent a relatively small subgroup of breast cancer patients, with an estimated prevalence of 2-7%. These tumors are similar to ERneg disease in their molecular landscape, clinicopathological characteristics, prognosis, and response to therapy. Nevertheless, a proportion may retain some degree of ER signaling dependency, and the possibility of responding to some degree to endocrine therapy cannot be completely ruled out. This review article discusses the most important considerations regarding the definition of ER positivity, pathology assessment, prognosis, and therapeutic implication of ERlo breast cancer from the medical oncology perspective.

Purpose: The SARS-CoV-2 pandemic was declared a global public health emergency. Determinants of mortality in the general population are now clear, but specific data on patients with breast cancer (BC) remain limited, particularly in developing nations. Materials and methods: We conducted a longitudinal, multicenter cohort study in patients with BC and confirmed SARS-CoV-2 infection. The primary end point was the proportion of patients on treatment for severe SARS-CoV-2 infection (defined as need for hospitalization) or early death (within 30 days of diagnosis). Data were evaluated sequentially in the following way: i) univariate Fisher’s exact test; ii) multivariable logistic regression analysis; and iii) multivariable logistic regression. In items i and ii only those with P< 0.1 are considered significant and in stage iii only those with p< 0.05 were the final significant variables. We divided patients’ data into three major variable domains: a) signs and symptoms; b) comorbidities; and c) tumor and treatment characteristics; in item ii each variable domain was tested separately, finally, in item iii the significant variables of all domains were tested together and we called it the integrative step. Results: From April 2020 to June 2021, 413 patients with BC and COVID-19 were retrospectively registered, of which 288 (70%) had an identified molecular subtype and 273 (66%) had stage information. Most patients were on active systemic therapy or radiotherapy (73.2%), most of them in the curative setting (69.5%). The overall rate of severe SARS-CoV-2 was 19.7% (95% CI, 15.3-25.1). In the integrative multivariate analysis, factors associated with severe infection were metastatic setting, chronic pain, acute dyspnea, and cardiovascular comorbidities. Recursive partitioning modeling used acute dyspnea, metastatic setting, and cardiovascular comorbidities to predict non-progression to severe infection, yielding a negative predictive value of 84.9% (95% CI, 78.9%-88.3%). Conclusion: The rate of severe COVID-19 in patients with BC is influenced by prognostic factors that partially overlap with those reported in the general population. High-risk patients should be considered candidates to active preventive measures to reduce the risk of infection, close monitoring in the case of exposure or SARS-CoV-2 -related symptoms and prophylactic treatment once infected. Citation Format: Fanny Cascelli, Matheus Costa e Silva, Rodrigo Dienstmann, Bruno L. Ferrari, Carlos Gil Ferreira, Max S. Mano, Jorge Canedo, Diego Cunha, Daniel Luiz Gimenes, Aline Goncalves. Determinants of severe COVID-19 infection in Patients with Breast Cancer from a Community Oncology Practice in Brazil [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-36.

10559 Background: As a reaction to the COVID-19 pandemic, a nation-wide lockdown was enforced in Brazil in March 2020, cancer care was impacted, and cancer screening reduced. Therefore, an increase in cancer diagnoses at more advanced stages was expected. In this study, we extracted data from our nationwide real-world database to evaluate the impact of the COVID-19 pandemic on the stage at diagnosis of breast cancer (BC) cases. Methods: We explored curated electronic medical record data of female patients, over 18 years of age, diagnosed with BC and with established disease stage based on the AJCC 8th edition, who started treatment or follow-up in the Oncoclínicas (OC) between Jan 1, 2018, and Dec 31, 2021. The primary objective was to compare stage distribution at first visit during COVID-19 pandemic (2020-2021) with a historical control cohort from a period prior to the pandemic (2018-2019). We investigated stage distribution according to age at diagnosis and tumor ER/HER2 subtype in univariate models. Associations were considered significant if they had a minimum significance (P < 0.1 in Chi-square test). The historical numbers of patients with BC at OC make it possible to identify differences in the prevalence of stages in the order of 5% comparing pre and post pandemic periods with a statistical power greater than 80%. Results: We collected data for 11,752 patients with initial diagnosis of BC, with 6,492 patients belonging to the pandemic (2020-2021) and 5,260 patients to the pre-pandemic period (2018-2019). For both ER+/ HER2- and HER2+ tumors, there was a lower percentage of patients with early-stage (defined as stage I-II) in the years 2020-2021 vs 2018-2019 and a considerable increase in advanced-stage disease (defined as stage IV). For triple negative BC (TNBC), there was a significant higher percentage of patients with advanced-stage disease in the pandemic vs pre-pandemic period (table 1). Age over 50 years was associated with a greater risk of advanced stage at diagnosis after the onset of the pandemic, with an absolute increase of 7% (P two-sided <0.01) Conclusions: We observed a substantial increase in cases of advanced-stage BC in OC institutions as a result of delays in BC diagnoses due to the COVID-19 pandemic. The impact appeared greater in older adults, potentially because of stricter confinement in this group. [Table: see text]

e18638 Background: The American Society of Clinical Oncology (ASCO) and the European Society of Medical Oncology (ESMO) annual meetings as well as their GI dedicated meetings (ASCO GI and ESMO GI) have the premise to accept abstracts for oral presentations that have not been previously presented. Methods: We conducted a review of all 220 abstracts involving phase II or III trials of systemic therapies that have been presented orally from June 2019 to January 2023 at ASCO, ASCO GI, ESMO and ESMO GI meetings to evaluate the incidenceof repetitive presentations of the same trial in different meetings as well as their relationship to pharmaceutical industry sponsorship. ANOVA test was used to compare means between different groups and p values of ≤ 0.1 were considered significant. Results: Overall, 20,9% of accepted oral abstracts from phase II or III trials were replicated during the 4-year time frame. Of them, 39% were phase II, 61% phase III, 72% pharma sponsored, 39% included developing countries, and 59% were positive. The association of industry sponsorship and study positivity indicated a variation of up 3,55 appearances (p 0,017) in the number of times this research was orally presented. Conclusions: Our findings suggest that almost 20% of oral abstracts involving systemic therapies in GI cancers are presented more than once at relevant meetings, especially those with positive results and sponsored by pharma. Our study highlights the need for a more effective oral abstract selection system in oncology meetings.