Cohort profile: COBLAnCE: a French prospective cohort to study prognostic and predictive factors in bladder cancer and to generate real-world data on treatment patterns, resource use and quality of life.

Bladder cancer is a complex disease with a wide range of outcomes. Clinicopathological factors only partially explain the variability between patients in prognosis and treatment response. There is a need for large cohorts collecting extensive data and biological samples to: (1) investigate gene-environment interactions, pathological/molecular classification and biomarker discovery; and (2) describe treatment patterns, outcomes, resource use and quality of life in a real-world setting.

COBLAnCE (COhort to study BLAdder CancEr) is a French national prospective cohort of patients with bladder cancer recruited between 2012 and 2018 and followed for 6 years. Data on patient and tumour characteristics, treatments, outcomes and biological samples are collected at enrolment and during the follow-up.

We describe the cohort at enrolment according to baseline surgery and tumour type. In total, 1800 patients were included: 1114 patients with non-muscle-invasive bladder cancer (NMIBC) and 76 patients with muscle-invasive bladder cancer (MIBC) had transurethral resection of a bladder tumour without cystectomy, and 610 patients with NMIBC or MIBC underwent cystectomy. Most patients had a solitary lesion (56.3%) without basement membrane invasion (71.7% of Ta and/or Tis). Half of the patients with cystectomy were stage ≤T2 and 60% had non-continent diversion. Surgery included local (n=298) or super-extended lymph node dissections (n=11) and prostate removal (n=492). Among women, 16.5% underwent cystectomy and 81.4% anterior pelvectomy.

COBLAnCE will be used for long-term studies of bladder cancer with focus on clinicopathological factors and molecular markers. It will lead to a much-needed improvement in the understanding of the disease. The cohort provides valuable real-world data, enabling researchers to study various research questions, assess routine medical practices and guide medical decision-making.

BMJ open. 2023 Dec 20*** epublish ***

Thierry Lebret, Julia Bonastre, Aldéric Fraslin, Yann Neuzillet, Stéphane Droupy, Xavier Rebillard, Dimitri Vordos, Laurent Guy, Arnauld Villers, Marc Schneider, Patrick Coloby, Jean Lacoste, Arnaud Méjean, Jacques Lacoste, Jean-Luc Descotes, Pascal Eschwege, Guillaume Loison, Hélène Blanché, Odette Mariani, Bijan Ghaleh, Anthony Mangin, Nanor Sirab, Karine Groussard, François Radvanyi, Yves Allory, Simone Benhamou

Urology, Hôpital Foch, Suresnes, France., Biostatistics and Epidemiology, Gustave Roussy, Villejuif, France., Urology, Centre Hospitalier Universitaire de Nimes, Nimes, France., Urology, Clinique Beau Soleil, Montpellier, France., Clinical Investigation Center 1430, INSERM, Créteil, France., Urology, University Hospital Centre Gabriel Montpied, Clermont-Ferrand, France., Urology, Claude Huriez Hospital, Lille, France., Urology, Hopitaux Civils de Colmar, Colmar, France., Urology, University Hospital Center René Dubos, Cergy-Pontoise, France., Urology, Private Hospital of Provence, Aix-en-Provence, France., Urology, Hopital Europeen Georges Pompidou, Paris, France., Urology, Atlantis Clinic, Saint-Herblain, France., Urology, CHU Grenoble Alpes, Grenoble, France., Urology, CHU de Nancy Hôpital de Brabois Adultes, Vandoeuvre-les-Nancy, France., Urology, la Croix du Sud Clinic, Quint Fonsegrives, France., Fondation Jean Dausset, Paris, Île-de-France, France., Biological Resources Center, Curie Institute Hospital Group, Paris, France., Biological Resources Platform, Hôpital Henri Mondor, Creteil, France., Pathology, Curie Institute, Paris, France., U1018, INSERM, Villejuif, France., UMR444, CNRS, Paris, France., Patholgy, Curie Institute Saint Cloud, Saint-Cloud, France., U1018, INSERM, Villejuif, France .