Introduction: Residual cancer burden (RCB) after neoadjuvant chemotherapy (NAC) can accurately predict disease recurrence and survival in breast cancer. In this context, end of treatment (EOT) image-guided response assessment could be useful to adapt treatment for individual patients. Our main objective was to assess the effectiveness of 18F-FDG PET/CT and MRI in determining NAC response. Methods: Patients with surgically resectable breast cancer (stages II-III) were prospectively included and evaluated with 18F-FDG-PET/CT and MRI before and after standard-of-care neoadjuvant chemotherapy (NAC). Ultrasound guided breast biopsy was performed before NAC and pathologic examination with residual cancer burden (RCB) scoring was performed after surgery. Standard uptake values (SUVmax and SUVmean) from baseline PET scans were measured. EOT images results were compared with RCB scores to assess the sensitivity and specificity of (EOT) 18F-FDG-PET/CT and MRI images. A multinomial logistic regression was performed to assess predictors of pathological response. A p-value of 0.05 was considered significant. Results: 30 patients were included, with 25% showing complete pathological response. EOT 18F-FDG-PET/CT images had a sensitivity of 55% and specificity of 100% to predict RCB > 0, while EOT MRI had a sensitivity of 65% and specificity of 66,6%. Luminal tumors showed significant lower baseline SUVmean and SUVmax values than triple-negative tumors. Ki67 expression didn´t correlate with treatment outcome. High estrogen receptor expression level was significantly associated with non-complete pathological response and higher false negative rates in both EOT 18F-FDG-PET and MRI images (7/8 in PET and 6/7 in MRI). Conclusions: 18F-FDG-PET / CT could be a useful diagnostic tool to assess neoadjuvant chemotherapy treatment response in breast cancer, showing greater specificity than MRI to predict pathological response. A high expression of estrogen receptors could lead to a high rate of false negative findings, both in PET and MRI. A greater number of cases is required to validate these findings. Citation Format: Marco Guarin, M. Eugenia Azar, Carolina Tinetti, M. Dolores Mansilla F., Mauro Namias, Pilar Carballo, Lucia Santamarina, Jorgelina Cavallero, Romina Moreau, Christian Gonzalez, Valeria Caceres, Eduardo Gonzalez, Gabriel Bruno. 18F-FDG-PET/CT and MRI in the assessment of neoadjuvant chemotherapy treatment response in breast cancer. Correlation with pathological response [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 PS3-27.

Background: Argentina is a country with inequalities in terms of healthcare, specially in genetics diseases. The lack of knowledge about hereditary cancer, the small number of genetic counselors and the difficulty of access to genetic testing are barriers to overcome to position genetic counseling (GC) as a standard of care. Objective: Describe our experience implementing GC as a standard of care for all patients with breast cancer (BC), and propose a new workflow to optimize referral to GC. The aim is to obtain GC and genetic testing prior to the primary treatment. Methods: In January 2015, the breast cancer unit established GC as a standard of care on all their patients. The institution didn’t have GC, so a breast cancer surgeon, part of the core team, was trained in GC and the rest of the team was trained to refer patients according to international guidelines. That surgeon and a psycho-oncologist formed the breast cancer genetic counseling section (BCGCS). They have interviewed patients and their families and have supported them and their medical team all over the GC process and testing. Results: From January 2015 to December 2018, 535 patients were evaluated by the BCGCS. 63% of patients were refered by breast surgeons, 12% by clinical oncologist, 19% by other units, 1% by the patients themselves and 5% from other institutions. The average time until the first GC consultation was 35 days (1-60 days). A minimum of two GC consultations per patient were performed. 243 patients were referred for genetic testing and 280 were not (27 without criteria, 35 were not index case, 19 psychological reasons and 147 patients were requested additional information). From the 243 patients, 139 didn’t have access to genetic testing due to lack of health insurance coverage. 104 test were successfully performed: 2 exomes (2 VUS: CHEK2 and TSC2), 81 BRCA1/2 (20 positives), 8 panels (3 VUS: ATM, RECQL, STK11) and 13 family mutations (5 positives: 4 BRCA and 1 CHEK2). Only two patients had a positive BRCA test before their primary treatment, both chose a bilateral mastectomy and one of them was included in the Olympia trial. Due to the success of the BCGCS, in 2017 a gynecologist and in 2018 an oncologist were trained in GC. The first one is part of the gynecological cancer unit and the second is part of the gastrointestinal cancer unit. Conclusion: Due to the presence of trained professionals as part of core teams, those units were continuously educated in genetics. That led to more and earlier referral to GC. We propose the following workflow to achieve better and more referrals of patients to GC, optimizing time and resources. Proposed WorkflowBackground requirements: Surgeon specialized in breast cancer trained in GC and Psycho-oncologist with basic knowledge of cancer genetics. Breast unit trained in hereditary cancer and referral guidelines.-Step one) Admission to breast unit with identification of patients with genetic counseling criteria according with national and international guidelines. *-Step two) Treatment Focus Genetic Testing is needed? (metastatic breast cancer, triple negative breast cancer, breast and ovarian cancer)1) Yes (always request psycho-logical support and explain the workflow)1A) Had family history of cancer?(1Aa) Yes: request a limited panel (BRCA1 / 2, PALB2, Tp53, Pten and other gene if an other syndrome is suspected) and send it to BCGCS**(1Ab) No: request BRCA1 / 2 and PALB2 testing(1Abi) Negative result. End of process(1Abii) Positive result or VUS: send to BCGCS**2) No: send to BCGCS.*** Rapid genetic testing is strongly encouraged.** Always explain about genetic counseling process and information needed prior to consultation. Citation Format: Maria Dolores Mansilla Figueroa, D Bequelman, J Cavallero, O Sturla, H Ursino, V Caceres, E Gonzalez. A new workflow for breast cancer genetic counseling referral. Experience of an public oncological reference center in Argentina [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-37.

Background: Over the last years, decreasing invasiveness to achieve less morbidity has been the trend for surgical procedure but axillary management after neoadjuvant chemotherapy (NAC) remains controversial. Different authors have shown the efficacy of sentinel lymph node biopsy (SLNB) to assess axillary response in patients who underwent NAC encouraging the use of these techniques instead of axillary lymph node dissection (ALND) in breast cancer patients. Argentinian surgeons don’t have a consensus guideline on the management of the axilla in patients after NAC, therefore the treatment of the axilla widely varies. This survey has been developed to assess the management of the axilla after NAC among argentinian breast surgeons. Methods: Members of the Argentinian Society of Breast Surgeons were invited by e-mail to complete an anonymous online survey between April 1st and May 31th of 2021. The survey consisted in 17 single-answer multiple choice questions (each question having 4 options). The surgeons had the option to write their own custom response on a comment field. Results: Of the 731 members, 263 answered the survey. 71% treated less than 50 neoadjuvant breast cancer patients last year. Axillary ultrasound is considered a standard tool in the initial evaluation of the axilla by 81% of participants and 73% performed core needle biopsy in case of suspicious node before NAC. 78% marked suspicious nodes before NAC (the majority with charcoal). 24% supported that ALND could be omitted only in cN0 patients, 55% in cN0- cN1, 9% in cN0-cN1-cN2 and 15% in any initial stage with a favorable response to NAC. 75% of the respondents evaluated axillary response after NAC using axillary ultrasound prior surgery. 15% performed ALND when there were any suspicious node by ultrasound. Most of the surgeons (76%) considered that double method (blue dye and radioisotope) allows better identification rate. 77% considered that at least three nodes and resection of the marked node is mandatory to reduce the false negative rate of the sentinel lymph node biopsy (SLNB) after NAC. 63% considered that pathologic complete response in the axilla is necessary to omit ALND and 37% omitted the ALND in the presence of positive sentinel node after NAC. 131 of the interviewed work in a public hospital and private practice, 27 of them (20%) can’t manage the axilla in the same way in both places because the lack of technology (gamma detection probe technology for example) at public hospitals. Discussion: The management of the axilla after NAC is a challenge for breast surgeons and forces them to personalize treatments and stay informed regarding changes in the scientific evidence. Axillary ultrasound is a widely-used method by argentine surgeons, it allows them to identify suspicious lymph nodes, perform core needle biopsies, and mark them, but an excessive use can also lead to unnecessary ALND. There is not consensus about the importance of pre- and post-NAC stage in deciding to perform only SLNB or ALND. Twenty percent of the surgeons perform SNLB only in cN0 patients, and on the other hand, 37% will omit the ALND even in the presence of positive sentinel node after NAC, extrapolating results from trials that may not fit in these patients. The high fragmentation and decentralization in the provision of health care services that characterizes Argentina’s health system is an obstacle to manage the complexity of neoadjuvant breast cancer patients. Conclusions: There is no standard management of the axilla in patients that undergo NAC in Argentina. Breast surgeons should gathered together to develop clinical practice guidelines in this matter and design strategies to improve the management of the neoadjuvant breast cancer patients in Argentina. Citation Format: M. Eugenia Azar, M. Dolores Mansilla F., Jorgelina Cavallero, Ornella Sturla, Hernan Ursino, Gaston Berman, Martin Ipiña, Andrea Aguilar, Valeria Caceres, Eduardo Gonzalez. Axillary surgery after neoadjuvant chemotherapy in breast cancer - Survey among Argentinian breast surgeons [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-01-08.

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