In randomised phase III cancer clinical trials, the most objectively defined and only validated time-to-event endpoint is overall survival (OS). The appearance of new types of treatments and the multiplication of lines of treatment have resulted in the use of surrogate endpoints for overall survival such as progression-free survival (PFS), or time-to-treatment failure. Their development is strongly influenced by the necessity of reducing clinical trial duration, cost and number of patients. However, while these endpoints are frequently used, they are often poorly defined and definitions can differ between trials which may limit their use as primary endpoints. Moreover, this variability of definitions can impact on the trial's results by affecting estimation of treatments' effects. The aim of the Definition for the Assessment of Time-to-event Endpoints in CANcer trials (DATECAN) project is to provide recommendations for standardised definitions of time-to-event endpoints in randomised cancer clinical trials.

We will use a formal consensus methodology based on experts' opinions which will be obtained in a systematic manner.

Definitions will be independently developed for several cancer sites, including pancreatic, breast, head and neck and colon cancer, as well as sarcomas and gastrointestinal stromal tumours (GISTs).

The DATECAN project should lead to the elaboration of recommendations that can then be used as guidelines by researchers participating in clinical trials. This process should lead to a standardisation of the definitions of commonly used time-to-event endpoints, enabling appropriate comparisons of future trials' results.

There is no methodology to provide appropriate definitions for survival endpoints. As such, including or excluding an event in a survival endpoint definition is only based on opinion from experts. For this reason, we launched the DATECAN-1 project in 2009. Its objective is to elaborate standardized definitions for survival endpoints in randomized clinical trials, based on a rigorous and validated consensus methodology. Once this project will be finalized (2012), guidelines for the definitions of survival endpoints to be used in clinical trials will be available.

This collaborative work involves the network of the statisticians from Regional Comprehensive Cancer Centers (Bordeaux, Lille, Montpellier, Dijon, Paris, Toulouse), the network of the Cancer Data Centers (CTD) of the French National Cancer Institute (INCA; Montpellier, Bordeaux, Curie, Dijon-GERCOR) as well as the Headquarters from the European Organization for Research and Treatment of Cancer (EORTC). This project is supported by a 2009 grant from the French League Against Cancer .

The DATECAN-1 project relies on a validated formal consensus method (Fitch K. The Rand/UCLA appropriateness method user's manual. 2001). This consensus approach formalizes the degree of agreement among experts by identifying and selecting the points on which experts agree, disagree or are undecided. The guidelines are subsequently based on agreement points. It is a rigorous and explicit method since it involves international experts in clinical trials in the field of the targeted cancer localizations. This method involves two rounds of rating (questionnaires) and an in-person meeting to address points for which consensus has not been reached yet.

We published the methodology of the consensus process (Bellera et al. Eur J Cancer 2013).

Guidelines have now been published following the international consensus process, for pancreatic cancer, sarcoma and GIST, beast cancer and renal cell carcinoma (See "Citations filed" below). For other localization (head and neck, stomach, colon): guidelines are ongoing.

Inclusion Criteria:

• Sarcoma / GIST
• Breast cancer
• Pancreatic cancer
• Renal cell carcinoma
• adjuvant colon cancer
• early non small cell lung cancer

Exclusion Criteria :

- Individual patient data unavailable

No patient will be included.