Impact of Whole Genome Doubling on Detection of Circulating Tumor DNA in Colorectal Cancer

Objective: Circulating tumor DNA (ctDNA) is a candidate biomarker of cancer with practice-changing potential in the detection of both early and residual disease. Disease stage and tumor size affect the probability of ctDNA detection, whereas little is known about the influence of other tumor characteristics on ctDNA detection. This study investigates the impact of tumor cell whole-genome doubling (WGD) on the detection of ctDNA in plasma collected preoperatively from newly diagnosed colorectal cancer (CRC) patients. Methods: WGD was estimated from copy numbers derived from whole-exome sequencing (WES) data of matched tumor and normal DNA from 833 Danish CRC patients. To explore if tumor WGD status impacts ctDNA detection, we applied tumor-informed ctDNA analysis to preoperative plasma samples from all patients. Results: Patients with WGD+ tumors had 53% increased odds of being ctDNA positive (OR = 1.53, 95%CI: 1.12–2.09). After stratification for UICC stage, the association persisted for Stage I (OR = 2.44, 95%CI: 1.22–5.03) and Stage II (OR = 1.76, 95%CI: 1.11–2.81) but not for Stage III (OR = 0.83, 95%CI: 0.44–1.53) patients. Conclusion: The presence of WGD significantly increases the probability of detecting ctDNA, particularly for early-stage disease. In patients with more advanced disease, the benefit of WGD on ctDNA detection is less pronounced, consistent with increased DNA shedding from these tumors, making ctDNA detection less dependent on the amount of ctDNA released per tumor cell

Prevalence of low anterior resection syndrome at a regional Australian centre

BACKGROUND: With decreasing indication for abdominoperineal resection and an increase in sphincter preserving surgery, there is a growing population of patients who suffer from low anterior resection syndrome (LARS). The aim of this study is to use the LARS score to determine the prevalence of LARS at a regional centre in Australia and determine the effect of short- and long-course neoadjuvant therapy, anastomotic technique and interval from surgery will also be assessed. METHODS: Patients who had undergone an anterior resection (high, low or ultralow) at a regional centre over an 11-year period were identified. Eligible patients were contacted to complete a LARS score questionnaire. Results were analysed to determine the rate of major LARS and possible causative roles of certain patient and treatment-related variables. RESULTS: A total of 64 of 76 patients (84%) returned completed questionnaires. The prevalence of major LARS was 37.5%. Short-course neoadjuvant therapy appeared to be more likely to be associated with major LARS compared to long course (odds ratio (OR) = 2.4, 95% confidence interval (CI) 0.37-15.3, P = 0.35); however, this did not reach statistical significance. Rates of major LARS appear to decrease slowly over time and J-pouch colonic anastomosis appears to be slightly protective against major LARS (OR = 0.7, 95% CI 0.12-3.9, P = 0.70); however, neither results were statistically significant. CONCLUSION: The rate of major LARS at this regional centre is 37.5%. Larger prospective multicentre studies are required to determine impact of variables such as type of neoadjuvant therapy, anastomotic techniques and progression of LARS over time