source: Familial Cancer
Gibbons DC, Sinha A, Phillips RK, Clark SK
Familial adenomatous polyposis (FAP) is a dominantly inherited colorectal cancer (CRC) syndrome with an untreated lifetime prevalence of CRC close to 100% and extracolonic manifestations (ECM) of increasing clinical significance. This study examined the effect of systematic callup and prophylactic colectomy on FAP survival. Patients diagnosed, treated and followed-up at our institution were analysed. ‘Callups’ were those identified via the callup system; ‘probands’ were those identified by other means. Proportions were analysed by Chi-squared or Fischer’s exact test. Mortality rates were indirectly standardised to the UK population. Survival curves from birth were estimated by Kaplan–Meier. A total of 439 patients (293 callups, 146 probands) were analysed. Crude mortality rates (CMRs) of callups and probands were 4.85 per 1,000 person years (PY) and 9.71 per 1,000 PY, respectively—a rate ratio of 0.50 (95% CI 0.34–0.72, P = 0.0001). The standardised mortality ratio (SMR) of callups was non-significantly lower than probands (4.12 vs. 4.70). Callups experienced non-signifi- cantly lower age-band specific SMR up to 45 years. More probands died of CRC (42.4 vs. 22.5%, P = 0.025), whereas more callups died of ECM (30.6 vs. 13.4%, P = 0.027). Median survival was 64 years for callups and 60 years for probands; survival curves did not differ significantly (P = 0.253). The crude mortality rate of callups is approximately half that of probands. As fewer callups die of CRC, a greater proportion die of ECMs. Callups experienced nonsignificantly reduced mortality up to 45 years. Whilst the FAP callup system reduces CRC risk, mortality attributable to ECMs needs to be addressed.
Imperial College London
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