Risk factors predicting desmoid occurrence in patients with familial adenomatous polyposis: a meta‐analysis

Aim Desmoid tumours (DT) are myofibroblastic proliferations occurring in 15% of patients with familial adenomatous polyposis (FAP). Several small series have analysed the incidence of DT and predisposing risk factors. Using meta‐analytical techniques, this study aimed to identify risk factors for DT development in patients with FAP. Method Studies of sporadic DT were excluded. The study end‐points were the incidence of DT in FAP and DT development by gender, adenomatous polyposis coli (APC) mutation, family history of DT and previous abdominal surgery. A random effect Mantel–Haenszel model was used to calculate odds ratios for each risk factor and age group. Results Ten studies of 4625 patients with FAP fulfilled our inclusion criteria. A total of 559 (12%) patients developed DT. Cumulative analysis demonstrated that 80% of DT developed by age 40, the peak incidence rate being in the second and third decades. A positive family history of DT was the most significant risk factor (OR 7.02, 95% CI 4.15–11.9, P < 0.001). An APC mutation 3′ to codon 1399 (OR 4.37, 95% CI 2.14–8.91, P < 0.001) and previous abdominal surgery (OR 3.35, 95% CI 1.33–8.41, P = 0.01) were also implicated. Women were more likely to develop DT (OR 1.57, 95% CI 1.13–2.18, P = 0.007). Conclusion There is consistency amongst polyposis registries in documenting the incidence and risk factors for DT development. Having a positive family history for DT is of greater significance than a 3′ mutation, suggesting the existence of modifier genes, independent of the APC genotype–phenotype correlation. Few of these risk factors are modifiable. Delaying prophylactic surgery could be appropriate in female patients with a 3′ APC mutation and attenuated polyposis.