Risk factors and protective measures for desmoid tumours in familial adenomatous polyposis: retrospective cohort study.

Background: Familial adenomatous polyposis is a cancer-predisposing syndrome caused by germline pathogenic variants of the adenomatous polyposis coli gene, leading to numerous colorectal polyps and a high risk of colorectal cancer. Desmoid tumours have become significant in the management of familial adenomatous polyposis after a colectomy, yet the exact incidence remains undetermined due to a lack of dedicated surveillance.

Methods: This retrospective study accessed data from the prospectively maintained Hereditary Digestive Tumours Registry from 2000 to 2023. Desmoid-free survival was analysed using Cox regression and Kaplan-Meier curves.

Results: A total of 202 patients with familial adenomatous polyposis who underwent colorectal surgery were enrolled. Of the patients, 21 (10.4%) developed intra-abdominal desmoid tumours after surgery. Desmoid tumours were associated with surgical procedure, histology of cancer at the time of surgery, and family history of intra-abdominal desmoid tumours. The overall desmoid-free survival probability at a median follow-up of 84 months was 90%. Histology of cancer at the time of surgery (HR 0.25 (95% c.i. 0.10 to 0.59)), family history of intra-abdominal desmoid tumours (HR 2.92 (95% c.i. 1.22 to 6.97)), an open approach compared with a laparoscopic approach (HR 2.43 (95% c.i. 1.03 to 5.73)), and a proctocolectomy compared with a rectal-sparing total colectomy (HR 3.01 (95% c.i. 1.28 to 7.10)) emerged as significant prognostic factors affecting desmoid-free survival.

Conclusion: A minimally invasive rectal-sparing total colectomy appears protective against the development of desmoid tumours. Early surgery does not seem to increase desmoid tumour risk. A dedicated surveillance regimen for desmoid tumours in patients with familial adenomatous polyposis is needed to improve outcomes and quality of life.