ADC as a predictor of pathologic response to neoadjuvant therapy in esophageal cancer: a systematic review and meta-analysis.

OBJECTIVE: Diffusion-weighted magnetic resonance imaging (DWI) is part of clinical practice. The aim of this study was to evaluate the role of apparent diffusion coefficient (ADC) as a predictor of pathologic response to neoadjuvant therapy (nCRT) in patients with esophageal cancer (EC). METHODS: The MEDLINE, Embase, and Google Scholar databases were systematically searched for studies using ADC to evaluate response to neoadjuvant therapy in patients with EC. Methodological quality of the studies was evaluated with the QUADAS tool. Data from eligible studies were extracted and evaluated by two independent reviewers. Meta-analyses were performed comparing mean ADC values between responders and non-responders to nCRT in three different scenarios: baseline (BL) absolute values; percent change between intermediate (IM) values and BL; and percent change between final follow-up (FU) value and baseline BL. RESULTS: Seven studies (n = 158 patients) were included. Responders exhibited a statistically significant percent increase in ADC during nCRT (mean difference [MD] 21.06%, 95%CI = 13.04-29.09; I2 = 49%; p = 0.12). A similar increase was identified in the complete pathologic response (pCR) versus non-complete pathologic response (npCR) subgroup (MD = 25.68%, 95%CI = 18.87-32.48; I2 = 0%; p = 0.60). At the end of treatment, responders also exhibited a statistically significant percent increase in ADC (MD = 22.49%, 95%CI = 9.94-35.05; I2 = 0%; p = 0.46). BL ADC was not associated with any definition of pathologic response (MD = 0.11%, 95%CI = - 0.21-0.42; I2 = 85%; p < 0.01). CONCLUSION: These results suggest that ADC can be used as a predictor of pathologic response, with a statistically significant association between percent ADC increase during and after treatment and pCR. ADC may serve as a tool to help in guiding clinical decisions. KEY POINTS: • DWI is routinely included in MRI oncological protocols. • ADC can be used as a predictor of pathologic response, with a statistically significant association between percent ADC increase during and after treatment and pCR.

A systematic review and meta-analysis of the aetiology of acute pancreatitis.

BACKGROUND: Gallstones and alcohol are currently the most frequent aetiologies of acute pancreatitis (AP). The aim of this study is to quantify these aetiologies worldwide, by geographic region and by diagnostic method. METHODS: A systematic review of observational studies published from January 2006 to October 2017 was performed. The studies provided objective criteria for establishing the diagnosis and aetiology of AP for at least biliary and alcoholic causes. A random-effects meta-analysis was used to assess the frequency of biliary (ABP), alcoholic (AAP) and idiopathic AP (IAP) worldwide and to perform 6 subgroup analyses: 2 compared diagnostic methods for AP aetiology and the other 4 compared geographic regions. RESULTS: Forty-six studies representing 2,341,007 patients of AP in 36 countries were included. The global estimate of proportion (95% CI) of aetiologies was 42 (39-44)% for ABP, 21 (17-25)% for AAP and 18 (15-22)% for IAP. In studies that used discharge code diagnoses and in those from the US, IAP was the most frequent aetiology. ABP was more frequent in Latin America than in other regions. CONCLUSION: Gallstones represent the main aetiology of AP globally, and this aetiology is twice as frequent as the second most common aetiology.