ctDNA as a predictor of outcome after curative resection for locally advanced rectal cancer: systematic review and meta-analysis.

AIM: To assess the efficacy of ctDNA measurement at different time intervals in predicting response and prognosis in patients diagnosed with locally advanced rectal cancer (LARC) who underwent neoadjuvant treatment prior to curative resection. METHOD: English language randomized controlled trials and observational studies, published from 1946 to January 2024, comparing outcomes between ctDNA-positive and ctDNA-negative patients with LARC undergoing neoadjuvant treatment prior to curative surgical resection were included in the search. The search included Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and the Cochrane Database of Systematic Reviews (CDSR). RESULTS: Data for 1022 patients were analysed. Patients with positive ctDNA in the preoperative period had more than five times the risk of developing distant metastasis (RR [95% CI] 5.03 [3.31-7.65], p < 0.001), while those with positive ctDNA in the postoperative period had more than six times the risk (RR [95% CI] 6.17 [2.38-15.95], p < 0.001). There was no significant relationship between ctDNA status at baseline, pre-, or postoperative periods and achievement of pCR (RR [95% CI] 1.21 [0.86-1.7], 1.82 [0.94-3.55], 1.48 [0.78-2.82], p = 0.27, 0.08, and 0.23, respectively). However, patients with positive ctDNA in the pre- and postoperative periods had more than 13 and 12 times the risk of overall disease relapse after curative-intent treatment (RR [95% CI] 13.55 [7.12-25.81], 12.14 [3.19-46.14], p < 0.001), respectively. CONCLUSION: ctDNA could potentially guide treatment and follow-up in LARC, predicting high-risk patients for disease relapse, allowing individualized surveillance and treatment strategies. Prospective studies are needed for standardization.

Low vs. standard dose computed tomography in suspected acute appendicitis: Is it time for a change?

BACKGROUND: Clinical diagnosis is accurate in only 80% of patients with suspected appendicitis with negative appendectomy rates of up to 21%. In the UK the use of standard-dose CT (SDCT) is conservative due to concerns over radiation exposure and resource implications. The use of low dose computer tomography (LDCT) instead of standard dose computer tomography (SDCT) may partially address these concerns. AIM: To compare LDCT and SDCT in the diagnosis of appendicitis. METHODS: A literature search of the EMBASE and MEDLINE databases in July 2015 was conducted using the keywords 'low dose CT' and 'appendicitis'. Data were analysed and p values calculated using the Chi-square test. P values less than 0.05 were considered to be significant. RESULTS: LDCT (1.2-5.3 mSv) was not inferior to SDCT (5.2-10.2 mSv) in the diagnosis of acute appendicitis and proposing alternative diagnoses. SDCT was superior to LDCT in the negative predictive value of diagnosis of appendiceal perforation. There was no significant difference between LDCT and SDCT in negative appendectomy rate, appendiceal perforation rate and the need for additional imaging. CONCLUSION: LDCT is not inferior to SDCT in the diagnosis of acute appendicitis and proposing alternative diagnoses. Further studies are recommended to further assess the potential role of LDCT & its cost effectiveness. Its use may improve the current management of patients with suspected acute appendicitis.