Sunil Verma, MD, MSEd, FRCPC, associate professor, University of Toronto, chair, Breast Medical Oncology, Sunnybrook Odette Cancer Centre, discusses clinical trial endpoints in metastatic breast cancer trials.
Verma says the two most talked about endpoints in metastatic breast cancer are overall survival (OS) and progression-free survival (PFS). PFS is marred by biases and may not get the complete picture of how patients will do long term. When compared to OS, PFS is considered to be substandard.
OS has always been considered the gold standard if researchers can impact the survival of the patients, Verma says. The challenge with OS as an endpoint is that it only tells researchers if the patient is alive or deceased while PFS tells researchers if the patient has progressed or not.
Verma says the journey in between the PFS and OS, termed the post-progression survival, is also a very important journey. Based on research presented at the 2014 ASCO Breast Cancer Symposium, looking at OS on its own is incomplete and researchers need to focus on the post-progression survival.
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