Abstract P4-02-14: Impact of ACOSOG Z0011 trial at University Hospital in Brazil

Abstract

Abstract Background: The American College of Surgeons Oncology Group (ACOSOG) Z0011 trialwas a milestone in the surgical treatment of the axilla. Its results have made significant contributions in reducing the extent of breast surgery. In Brazil, this new approach was questioned, since the survival of the disease remains lower in the developing countries due to the difficulty in the early diagnosis, delay in the treatment and diagnosis in more advanced stages. Objective: To evaluate the overall survival and locoregional recurrence in patients with sentinel lymph node (SLN) metastatic from breast cancer with or without complete axillary lymph node dissection (ALND) treated at our institution. Methods: This retrospective cohort study evaluated patients with primary invasive breast cancer and clinically negative axilla who underwent lumpectomy and sentinel lymph node dissection (SLND) at the São Paulo Hospital, from February 2008 to December 2018. Patients with metastatic SLN were treated with SLND (group 1) or ALND (group 2). Group 1 was composed by the patients who met the inclusion criteria of ACOSOG Z0011 trial. Group 2 was composed by patients treated previous to the publication or by patients that had exclusion criteria according ACOSOG Z0011 trial. Overall survival was defined as the time relapsed from the date of surgery to death from any cause. Locoregional recurrence was determined by the presence of disease in the breast or ipsilateral lymph nodes in the axilla, supraclavicular, infraclavicular or internal mammary. Survival was analyzed with Kaplan-Meier method and comparison among groups with log-rank. Cox proportional-hazards model were applied. Statistical analysis was performed in SPSS version 20.0 and STATA12, with p value <0.05 considered significant. Results: A total of 415 patients were included in this study, 23.3% (97 patients) were identified as metastatic SLN, 56 patients were treated with SLND only (group 1) and 41 patients with ALND (group 2). The groups were homogeneous in relation to the variables: age group (50 years versus 51 years and over) (p = 0.279), race (p = 0.120), level of education (p = 0.142), pathological diagnosis (p = 0.210), histological grade (p = 0.983), hormonal receptors (p = 0.708), HER2 status (p = 0.695), pT (p = 0.334). Average age was 58.3 years (group 1) and 56.3 years (group 2), p = 0.456; and average tumor size was 1.8 cm (group 1) and 2.2 cm (group 2), p = 0.048. In group 1, the average number of resected lymph nodes was 2.7 and 91% of the cases only 1 lymph node was positive. In group 2, the average number of positive lymph nodes was 3.5 and only 17% had additional axillary disease. The SLND presented 35.7% micrometastasis compared to 2.4% in ALND (p <0.001) and a lower number of capsular extravasation (8.9%), in contrast to 41.5% in the ALND group (p <0.001). In addition, ALND group also had greater axillary involvement as evidenced by axillary pathological staging, with N1 (73.2%), N2 (19.5%), N3 (4.9%) and SLND group with N1 (62.5%) and no cases N2 or N3 (p <0.001). The average survival time, estimated using the Kaplan-Meier model, was 9.18 years (95% CI: 8.47-9.90). There was no difference in overall survival between patients who underwent SLND alone or ALND. The 5-year survival was 80.1% in the SLND and 87.5% in the ALND (p = 0.376). The locoregional recurrence was a rare event, average time of 5 years was 1.8% SLND and 7.7% ALND (p = 0.196). Only 4 locoregional recurrences were described and all occurred within 18 months of follow-up. Conclusions: Overall survival and locoregional recurrence in patients with metastatic axillary sentinel lymph node treated with SLND alone did not differ from those who underwent ALND, corroborating ACOSOG Z0011 data. The omission of axillary lymph node dissection and the implementation of this practice in our service benefits the patients treated with less aggressive surgeries and, potentially, produces lower morbidity. Citation Format: Afonso CelsoPinto Nazário, Simone Elias, Gil Facina, Vanessa Monteiro Sanvido. Impact of ACOSOG Z0011 trial at University Hospital in Brazil [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 P4-02-14.