Abstract 520P
Background
Follow-up in clinical practice is not standardized as in trials. Thus, guidelines for time-to-event endpoints in cancer trials cannot directly be applied to real world data. Definitions are needed to allow for correct interpretation and comparison of real-world studies. The primary aim is to establish guidelines for time-to-event endpoints of real-world data. Second, the endpoints are applied to patients with gastrointestinal cancer.
Methods
Definitions for calculating disease-free survival (DFS), recurrence-free survival (RFS) and progression-free survival (PFS) from real-world data extracted from patient records were established. Patients with colorectal, esophagogastric, pancreatic or hepatocellular carcinoma diagnosed in 2015-2018 with follow-up data were selected from the Netherlands Cancer Registry. Endpoints were calculated with Kaplan-Meier analysis according to the new definitions.
Results
The time interval is calculated from the date of diagnosis or treatment (depending on the research question) until the event or last follow-up date. The table presents the events to be included in DFS, RFS and PFS. The date of the event is the first date on which the event occurs, with the date of histological or cytological confirmation as first prioritization. The last date of follow-up is the last registered date of contact with an oncological relevant care provider on which information on disease recurrence or progression is available. Marginal differences were observed between DFS and RFS from primary diagnosis across all tumor types (n=17,440). Three year DFS ranged from 18% for pancreatic cancer to 78% for colon cancer, while one year PFS ranged from 10% for hepatocellular cancer to 35% for rectal cancer. Table: 520P
Events to be included in the different time-to-event endpoints
| Curative setting (i.e. no detectable disease) | Palliative setting (i.e. detectable disease) | ||
| Event | DFS | RFS | PFS |
| Recurrence (local, regional or distant) | X | X | n.a. |
| Progression | n.a. | n.a. | X |
| Occurrence new metastases | X | X | X |
| Second primary same topography | X | - | X |
| Death due to any cause | X | X | X ∗ |
DFS: disease-free survival; RFS: recurrence-free survival; PFS: progression-free survival; n.a.: not applicable.
∗For PFS, deaths until 90 days after the last follow-up date should be included.
Conclusions
This study provides uniform definitions for time-to-event endpoints using real-world data. Results for specific subgroups and guidelines for time to recurrence, time to progression and time to treatment failure will follow.
Legal entity responsible for the study
IKNL.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.