Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

P3-12-04: Involved Anterior Margins after Breast Conserving Surgery: Is Re-Excision Required?

Background: Complete tumour excision in breast conserving surgery (BCS) is critical for successful treatment; involved circumferential resection margins are associated with increased disease recurrence. However, the importance of an involved anterior margin is less clear. The purpose of this study was to audit an aggressive approach to involved anterior margins and hence assess whether anterior margin re-excision yields clinical benefit.

Material and Methods: A retrospective case note and pathology review was performed for all patients who underwent BCS between 2006 and 2010 through a single cancer centre. An involved margin was defined as <1mm clearance of invasive or in situ breast cancer. Results: 1667 patients underwent BCS for invasive and/or in-situ disease, of whom 114 (6.8%) underwent re-excision, most commonly for mixed invasive and in-situ pathology. The annual re-excision rate rose significantly (p<0.001), with no change in whole tumour diameter, specimen weight or specimen volume. A total of 170 involved margins were identified: most commonly the anterior margin (59 margins, 30.6%) followed by the posterior (39 22.9%) or inferior (31, 18.3%) margin. Patients with anterior margin involvement were more likely to have grade 3 invasive disease (p=0.0323) but less likely to have residual disease found at re-excision (2/49 vs. 32/101 margins, p=0.0033); there were no differences when in-situ characteristics were compared.

Conclusions: Re-excision of involved anterior margins rarely excises residual disease and may be unnecessary. Multidisciplinary teams should consider whether further therapy for an involved anterior margin is required on a patient by patient basis.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-12-04.

The Effect of Neoadjuvant Metformin on Breast Cancer Related Genes Clinical Trial – A Preliminary Result

Other authoring group: Dougal Adamson, Lee Baker, Douglas C Brown, Sally Chalmers, Amanda Degabriele, Janet Flinn, Kenneth Fowler, Avril Gunning, Grahame Hardie, Julie Lindsay, Gillian Little, Denis McLean, Robert Murdoch, Colin Purdie, Marta Reis, Valerie Walker.IntroductionMetformin, used in the treatment of diabetes for 50 years, has been linked to a reduced incidence of breast cancer and to an enhanced pathological response when administered concurrent with neoadjuvant chemotherapy. It has been postulated that the anti-neoplastic effect of metformin is through activation of AMP-activated protein Kinase (AMPK). The aim of this open label, randomised clinical trial was to investigate the effect of neoadjuvant metformin on gene expression in primary breast cancer.MethodsNon-diabetic women with histologically proven, operable, primary invasive breast cancer of ≥1cm in size were offered the trial following regional Research Ethics Committee approval.The trial had 2 arms, A and B: in arm A (8 patients), patients had core biopsies at three time points: one at presentation; one after a week of no treatment (internal control); and a further biopsy at the time of definitive surgery after at least 2 weeks of metformin. In trial arm B (47 patients), patients had core biopsies at two time points: one before randomisation to either take metformin or not, and one at the time of definitive breast surgery. Metformin was given as 500mg o.d. orally for one week, increased to 1g b.d. orally for at least another week and until the day prior to excisional breast surgery.RNA was extracted from formalin fixed cores and examined using a Disease-Specific Array for breast cancer on an Affymetrix platform (ALMAC Diagnostics Group, Craigavon, UK). Subsequent confirmatory polymerase chain reaction and immunohistochemistry techniques were used to examine the histological material.ResultsType of results expected:[Change of target gene expression in response to neoadjuvant metformin; symptomatic drug toxicities; potential for therapeutic effects of metformin in non-diabetic patients in vivo.]Results from the first arm:The triplet of core biopsies from 6/8 (75%) of the A arm patients passed the GeneGhip QC and data integrity assessment. Patients were 41-65 (mean: 53) years, with IDC NST, grade II-III, and all ER positive. 270 genes were differentially expressed significantly by wounding, and 63 by metformin. Among the genes significantly over-expressed by metformin were AMPK-beta and PI3K; and those down regulated by metformin were AMPK-gamma and ADCY1. Samples from the B arm patients are in analysis.ConclusionThe gene expression changes identified in response to neoadjuvant metformin suggest that metformin improves DNA damage recognition and repair and regulates cancer cell metabolism. These results suggest mechanisms by which metformin could be efficacious in the treatment of breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3145.