P132 Prognosis and molecular characteristics of IBD-associated colorectal cancer: experience from a French tertiary-care center

Hammoudi, N.(1)*;Lehmann-Che , J.(2);Lambert, J.(3);Amoyel, M.(1);Maggiori, L.(4);Salfati, D.(1);Tran Minh, M.L.(1);Baudry, C.(1);Asesio, N.(1);Poirot, B.(2);Lourenco, N.(1);Corte, H.(4);Allez, M.(1);Aparicio, T.(1);Gornet, J.M.(1);

(1)APHP Saint Louis, Gastroenterology, Paris, France;(2)APHP Saint Louis, Molecular Biology, Paris, France;(3)APHP Saint Louis, Biostatistics, Paris, France;(4)APHP Saint Louis, Digestive Surgery, Paris, France;


Little is known about the prognosis of colorectal cancer associated with inflammatory bowel disease (CRC-IBD) in a real-world cohort in France.


We conducted a retrospective observational study including all patients presenting CRC-IBD in a tertiary French center between 1990 and 2021. Clinical and molecular data were collected. We analyzed overall survival (OS), progression free survival (PFS) and factors associated with prognosis. Outcome probabilities were analyzed using the Kaplan-Meier method.


Among 6510 patients, the incidence rate of CRC was 0.8% (N =49) with a median delay of 19.5 years after IBD diagnosis. The median age was 46 years, the main IBD was ulcerative colitis (59%), the primary tumor was rectal in 49% and localized at diagnosis in 69%. There was a previous exposure to immunosuppressants (IS) in 57% and anti-TNF in 29% of the cases. The most frequent mutation was TP53 (56%). A RAS mutation was observed in 37% of the whole population and 13% of metastatic patients. OS of the whole cohort was 45 months OS and PFS of synchronous metastatic patients was 20.4 months and 8.5 months respectively. Among the patients with localized tumor those previously exposed to IS had a better progression-free survival (39 months vs 23 months; p =0.05) and a better OS (74 vs 44 months; p =0.03). Only 2 patients (4%) experienced IBD relapse during follow-up despite IS and biologics discontinuation in all exposed patients.  Chemotherapy exposure was 53% and 93% in the adjuvant and metastatic setting respectively.   No unexpected side-effect was observed, the only reason for discontinuation was oxaliplatin-sensitive neuropathy.


Incidence of CRC is elevated in IBD patients with a poor OS in metastatic patients although IBD is not associated with under-exposure or increased toxicity to chemotherapy. Previous IS exposure may be associated with a better prognosis.