2F-4 CLINICAL AND ECONOMIC IMPACT OF PRIMARY TUMOUR (PT) IDENTIFICATION IN METASTATIC CANCER OF UNKNOWN PRIMARY TUMOUR (CUP): A POPULATION-BASED RETROSPECTIVE MATCHED COHORT STUDY

Monday, October 24, 2016: 4:45 PM
Bayshore Ballroom Salon F, Lobby Level (Westin Bayshore Vancouver)

Malek B. Hannouf, Ph.D., London Health Sciences Centre, London, ON, Canada, Eric Winquist, MD, MSc, Department of Oncology, Western University, London, ON, Canada, Salah Mahmud, MD, Ph.D., Department of Epidemiology and Cancer Registry, CancerCare Manitoba, Winnipeg, MB, Canada, Muriel Brackstone, MD, Ph.D, FRCSC, Deparment of Oncology and Surgery, Western University, London, ON, Canada, Sisira Sarma, Ph.D., Department of Epidemiology and Biostatistics, Western University, London, ON, Canada, George B. Rodrigues, MD, FRCPC, Ph.D., London Regional Cancer Program, London, ON, Canada, Peter Rogan, Ph.D., Department of Biochemistry & Computer Science, Western University, London, ON, Canada and Gregory S. Zaric, Ph.D., Ivey Business School, Western University, London, ON, Canada
Purpose: Several genomic tests have been developed to identify the PT in CUP. However, the value of identifying the PT in clinical practice for CUP patients remains questionable and difficult to prove in randomized trials. We aimed to estimate the clinical and economic impact of PT identification in CUP using a retrospective matched cohort study.

Methods: We used the Manitoba Cancer Registry to identify all patients initially diagnosed with metastatic cancer between 2002 and 2011 who survived at least 6 months following initial diagnosis. We defined patients to have CUP if the PT was found 6 months or more after initial diagnosis or never found during the course of disease. Otherwise, we considered patients to have metastatic cancer of known PT (CKP). We linked all patients with Manitoba Health administrative databases to estimate direct costs of healthcare utilization based on a phase-of-care approach. We used propensity-score matching technique to match each CUP patient with a CKP patient based on all known clinicopathologic characteristics. We compared treatments, two-year survival and costs of healthcare utilization between the two patient groups and assessed treatment effect on overall survival (OS) using Cox regression adjustment.

Results: Of the 5,839 patients found diagnosed with metastatic cancer, 395 had CUP (6.8%). A 1:1 matching created a matched group of 395 patients with CKP. Patients with CUP compared to CKP counterparts were less likely to receive surgery, radiotherapy, hormone therapy and targeted therapy, and more likely to receive toxic empiric chemotherapeutic agents. Having CUP was associated with reduced OS (HR= 1.31 [95%CI= 1.1-1.58] p= 0.005) but lost statistical significance with adjustment for treatment differences. Compared to CKP patients, CUP patients had an increase of $3,850CAD in the mean cost of initial diagnostic workup before diagnosis and $1,100CAD in the mean cost of end-of-life. CUP patients also had a reduction of $334CAD in the mean cost of initial cancer care after diagnosis and $4,200CAD in the mean cost of continuing cancer care.

Conclusion: Compared to CKP patients, CUP patients received fewer cancer treatments, had reduced OS, and used more healthcare resources for diagnostic workup and end-of-life but less healthcare resources for cancer care. Identifying the PT in CUP patients might enable use of more effective therapies, improve OS and more efficiently allocate healthcare resources.

See more of: ORAL ABSTRACTS: POPULATION HEALTH RESEARCH

See more of: 38th Annual North American Meeting of the Society for Medical Decision Making