Retrospective observational studies in ultra-rare sarcomas: A consensus paper from the Connective Tissue Oncology Society (CTOS) community of experts on the minimum requirements for the evaluation of activity of systemic treatments

Silvia Stacchiotti, Anna Maria Frezza, George D. Demetri, Jean‐Yves Blay, Jyoti Bajpai, Giacomo Giulio Baldi, Elizabeth H. Baldini, Robert S. Benjamin, Sylvie Bonvalot, Judith V.M.G. Bovée, Dario Callegaro, Paolo G. Casali, Sandra P. D’Angelo, Elizabeth J. Davis, Angelo Paolo Dei Tos, Elizabeth G. Demicco, Jayesh Desai, Palma Dileo, Mikael Eriksson, Hans Gelderblom, Suzanne George, Rebecca A. Gladdy, Mrinal M. Gounder, Abha A. Gupta, Rick L. M. Haas, Andrea Giráldez Hayes, Peter Hohenberger, Kevin B. Jones, Robin L. Jones, Bernd Kasper, Akira Kawai, David G. Kirsch, Eugenie S. Kleinerman, Axel Le Cesne, Roberta Maestro, Javier Martín‐Broto, Robert G. Maki, Aisha Miah, Emanuela Palmerini, Shreaskumar R. Patel, Chandrajit P. Raut, Albiruni R. Abdul Razak, Damon R. Reed, Piotr Rutkowski, Roberta Sanfilippo, Marta Sbaraglia, Inga‐Marie Schaefer, D. Strauß, Sandra J. Strauss, William D. Tap, David M. Thomas, Annalisa Trama, Jonathan C. Trent, Winette T.A. van der Graaf, Winan J. van Houdt, Margaret von Mehren, Breelyn A. Wilky, Christopher D.�M. Fletcher, Alessandro Gronchi, Rosalba Miceli, Andrew J. Wagner