Introduction The prognostic significance of adenoma detection in colorectal cancer (CRC) survivors is poorly characterised. This study aimed to determine if patients with synchronous adenomas (SAs) are more likely to develop metachronous adenomas (MAs) and its impact on locoregional recurrence and survival.

Methods Patients with stage I-III CRC undergoing curative surgery at our institution, between 2006 and 2012, were included. The SA group included patients with adenomas at pre-operative colonoscopy or in the resection specimen. SPSS version 21 was used for univariate analysis (chi-squared test) and multivariate analysis (logistic regression/Cox regression modelling).

Results In total, 562 patients (M:F 323:239, median age 69 years (62–77)) were included; 197 had SAs. Male gender and older age were significantly associated with SAs (p < 0.001 and p = 0.020 respectively). By 60 months, 70/366 (19%) patients undergoing colonoscopic examination developed MA. On univariate analysis, SA patients were more likely to develop MA than non-SA patients (26% versus 16% respectively, Odds ratio 1.91, p = 0.014). On multivariate analysis, the only independent predictor of MA by 24 months was SA at presentation. However, by 60 months, male gender and right sided tumours were independent predictors of risk of developing MA. SA patients had a significantly lowerl local recurrence rate compared to non-SA patients (2/188 (1%) versus 18/314 (5%), p = 0.008). After correction for age, sex and pathological T stage, no difference in overall (OS) or disease free survival (DFS) between SA patients and non-SA patients was observed (Hazards Ratio (HR) 0.926, p = 0.687 and HR 2.367, p = 0.460, respectively). Similarly, MA patients had similar OS compared to those that did not have MAs (OS 99 months versus 102 months, p = 0.504).

Conclusion At 5 years, proximal tumours and male gender were predictors of risk of developing metachronous adenomas. However, there was no difference in overall or disease free survival amongst patients presenting with SAs or MAs compared to patients without such adenomatous lesions. Detection of adenomas in CRC survivors does not indicate adverse prognosis.

Disclosure of Interest None Declared