Abstract P2-17-04: Real world treatment sequencing patterns in secondary breast cancer (SBC): Pathway visualisation using national datasets

BACKGROUND Treatment pathways in metastatic breast cancer are complex. The accelerated adoption of new medicines has resulted in an uncertain evidence base supporting their use. Uncertainties are related to the mismatch between trial-recruited and real-world populations and variation in the order of sequential drugs. Published examples describing real-world practice in SBC are scarce, mainly due to the complexity of the clinical pathways that rely on a mixture of chemotherapy, endocrine therapy and biologicals, often over a long period. We demonstrate how new opportunities in routine healthcare data allow a highly granular description of real-world treatment pathways and how this varies in light of patient (pt) case-mix. METHODS Scottish nationally available data source datasets for linkage included the National Cancer Registry, Scottish Morbidity Record, the National Cancer Quality Audit and the national Prescribing Information System. Scottish CHI number was the universal identifier for linkage. Key baseline characteristics included age, de-novo presentation, prior adjuvant treatments, co-morbidities, concomitant medications and socioeconomic status. Targeted and random sampling manual review was used to quantify missing data. R version 3.6 was used for analysis. RESULTS 345 pts were identified of which 276 had ER+HER2- SBC between 2012-2017. First line therapy included 68% (235 patients) endocrine therapy, 17% (59 pts) chemotherapy, 14% (50 pts) received no treatment. Subsequent treatment decisions, including best supportive care and death, have been tracked to identify 70 unique pathways with up to 8 lines of treatment. Graphical representation of treatment pathways is made using Sankey plots. Detailed data quality reports describe missing data rates over time and a comprehensive guide for analysts has been produced as a wiki [https://blogs.ed.ac.uk/canceroutcomes/edinburgh-cancer-informatics-wiki/]. CONCLUSIONS It is now possible to describe treatment sequences using routine, nationally available administrative healthcare data. Pathways are complex and do not always conform to standard guidelines. Interpretation requires modern graphical visualisation methods. Of the 235 patients who received first line endocrine therapy, 48% (114 patients) went on second line endocrine therapy, 22% (51 patients) were switched to chemotherapy, 0.4% (1 patient) entered a trial, 18% (43 patients) died on the treatment and 11% (26 patients) went on to best supportive care (BSC). Of the 59 patients who received first line chemotherapy, 36% (21 patients) received second line chemotherapy, 36% (21 patients) received second line endocrine therapy, 24% (14 patients) died on treatment and 5% (3 patients) went on to BSC. The 1 patient who entered a trial went on to have chemotherapy as next line of treatment. Citation Format: Olga Oikonomidou, Ashley Horne, M McMenemy, E Holly, L Murdoch, Caroline Michie, Richard L Hayward, Christina Lilley, Peter S Hall. Real world treatment sequencing patterns in secondary breast cancer (SBC): Pathway visualisation using national datasets [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 P2-17-04.