Abstract P2-01-10: Cumulative analysis of breast cancer sentinel lymph node identification rate by radioisotope: A 13-year experience
Authors: Chen Y-Y , Yu B-L , Lee C-C , Wei H-K , Lin C-W , Tsai T-J , Cheng T-Y , Chen C-M 
Published: March 2017

Abstract
Purpose:
To investigate the breast cancer sentinel lymph node(SLN) identification rate by radioisotope navigation over the past 13 years at a single cancer centre institution.
Method:
Retrospective, breast cancer sentinel lymph node data in the past 13 years was collected. Between May 2002 to August 2008, sulphur colloid was the radioisotope agent used at the institution. Between August 2008 to August 2012, the radioisotope agent was switched to phytate. Then, between September 2012 to June 2015, injection method of phytate was switched from subdermal to intradermal. The SLN identification rate from each three periods were compared and analysed.
Results:
In a 13-year period (May 2002~June 2015), a total of 5455 breast cancer axillary sentinel lymph node samples were collected. Each surgeon's first 50 cases were excluded, thus a reduction to 5105 samples were derived. 155 cases were bilateral. Out of the 5105 samples, 40 did not undergo radioisotope mapping.
During the 13-year period, total successful SLN identification rate was 96.7%(4897/5065). During the sulphur colloid period (May 2002~August 2008), successful SLN identification rate was 99.1%(996/1005). During the subdermal phytate period (August 2008~August 2012), successful SLN identification rate was 95.1%(2200/2313). During the intradermal phytate period (September 2012~June 2015), successful SLN identification rate was 97.4%(1701/1747).
After injection of radioisotope agent, lymphatic scan mapping may fail. However, radioisotope signals may still be detected by radioisotope navigator intra-operatively. During the sulphur colloid period (May 2002~August 2008), mapping failure rate was 5.2%(52/1005). SLN identification rate by intra-operative navigator after scan mapping failure was 96.1%(50/52). During the subdermal phytate period (August 2008~August 2012), mapping failure rate was 21.7%(501/2313). SLN identification rate by intra-operative navigator after scan mapping failure was 79.0%(396/501). During the intradermal phytate period (September 2012~June 2015), mapping failure rate was 12.8%(223/1747). SLN identification rate by intra-operative navigator after scan mapping failure was 83.4%(186/223).
Conclusion:
Different radioisotope agent may affect the identification rate of axillary sentinel lymph nodes in breast cancer patients. Change of injection method, such as from subdermal to intradermal, may improve identification rate in use of same radioisotope agent. Even when lymphatics scan mapping failed, intra-operative radioisotope navigator may still successfully identify axillary sentinel lymph nodes and avoid unnecessary dissection due to mapping failure.
Citation Format: Chen Y-Y, Yu B-L, Lee C-C, Wei H-K, Lin C-W, Tsai T-J, Cheng T-Y, Chen C-M. Cumulative analysis of breast cancer sentinel lymph node identification rate by radioisotope: A 13-year experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-10.