Abstract P1-01-06: Predictor of sentinel node positivity in screen-detected invasive breast cancer
Authors: Bichoo Raouef Ahmed , Elahi Mohammed Bilal , Dumitru Dorin , Ihsan Naila Bint , Khalifa Eiman , Sarker Masuma , Mahapatra Tapan K , Wooler Brendan Paul , Kneeshaw Peter , Grover Kartikae 
Published: March 2022

Abstract
Introduction: Sentinel lymph node biopsy represents the standard of care for staging axilla in breast cancer patients who are clinically node negative. ACOSOG Z11 trial results questioned the importance of low burden nodal disease. Results from the SOUND trial on omission of axillary surgery in selected patients with early stage breast cancer are still awaited. Breast screening programs aim to detect cancers at an early stage and are expected to have low burden of nodal disease. The aim of our study was to determine predictors of sentinel node biopsy positivity in invasive breast cancers detected on screening mammography. Methods: This retrospective study included patients with node negative invasive breast cancer detected on screening mammogram performed between April 2018 and March 2020 and subsequently underwent curative surgery including sentinel node biopsy at breast care unit of Castle Hill Hospital, Cottingham, U.K. We looked at patient’s clinical, radiological and pre-operative pathological features and correlated them with histological results of sentinel node biopsy. Statistical analysis of the data was performed using SPSS version 22 and p-value of 0.05 was considered significant. Results: We identified 304 patients who met inclusion criteria. The mean age of these patients was 62.71 ± 7.2 years (range 47-78 years). Majority (88%) of women were postmenopausal. Overall, the sentinel node positivity rate was 11.76%. Women over the age of 55 years were less likely to be node positive compared to younger women (9.9% vs 22%, p=0.016). Tumours less than 10mm in size had node positive rate of 5.5% compared to tumour larger than 21mm (25%, p = 0.000). In comparison to grade 2and grade 3 tumours, grade 1 tumours had lower node positivity rate, (5% vs 14.4%) but the difference did not reach statistical significance (p= 0.073). All women with tubular and mucinous histological subtypes (n=13) were node negative. All women with grade 1 tumours less than 10mm in size (n=48) had a negative sentinel node biopsy compared to women with grade 2 tumors more than 20mm (9/32=28% positivity rate) and p-value of 0.000. There was no association between oestrogen, progesterone and HER2 receptor status with sentinel lymph node positivity rate. Conclusion: In selected screen detected patients including those above the age of 55 years, having grade 1 cancer, and less than 10 mm size on pre-treatment imaging, there might be scope for omission of axillary surgery.
Citation Format: Raouef Ahmed Bichoo, Mohammed Bilal Elahi, Dorin Dumitru, Naila Bint Ihsan, Eiman Khalifa, Masuma Sarker, Tapan K Mahapatra, Brendan Paul Wooler, Peter Kneeshaw, Kartikae Grover. Predictor of sentinel node positivity in screen-detected invasive breast cancer [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 P1-01-06.