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Circulating tumour DNA (ctDNA) is an emerging field of cancer research. However, current ctDNA analysis is usually restricted to one or a few mutation sites due to technical limitations. In the case of massively parallel DNA sequencers, the number of false positives caused by a high read error rate is a major problem. In addition, the final sequence reads do not represent the original DNA population due to the global amplification step during the template preparation. We established a high-fidelity target sequencing system of individual molecules identified in plasma cell-free DNA using barcode sequences; this system consists of the following two steps. (i) A novel target sequencing method that adds barcode sequences by adaptor ligation. This method uses linear amplification to eliminate the errors introduced during the early cycles of polymerase chain reaction. (ii) The monitoring and removal of erroneous barcode tags. This process involves the identification of individual molecules that have been sequenced and for which the number of mutations have been absolute quantitated. Using plasma cell-free DNA from patients with gastric or lung cancer, we demonstrated that the system achieved near complete elimination of false positives and enabled de novo detection and absolute quantitation of mutations in plasma cell-free DNA. [ABSTRACT FROM AUTHOR]

Background Patients with esophageal cancer often have impaired respiratory function. Postoperative pulmonary complications frequently occur in patients undergoing esophagectomy. We instructed patients undergoing esophagectomy to do breathing exercise with Incentive Spirometer Coach 2 (Smiths medical) for at least two weeks before surgery, as well as smoking cessation. Methods We retrospectively reviewed medical records of 52 esophageal cancer patients who underwent spirometry both pre- and post- Coach 2 exercise between 2009 and 2017. We evaluated the change of respiratory function and postoperative complications. The influence of exercise was analyzed between patients who underwent neoadjuvant chemotherapy (NAC group, n = 36) and those treated without NAC (non-NAC group, n = 16). Results 39 males and 13 females were included. Median age was 65 (45–82). Surgical procedures were 48 subtotal esophagectomy, 3 transhiatal esophagectomy, and 1 pharyngo-laryngo-esophagectomy. Vital capacity (VC) and forced expiratory volume in one second (FEV1.0) were significantly improved through exercise; 3405 to 3600ml (P  = 0.021) and 2485 to 2555 ml (P  = 0.008), respectively. NAC group included more advanced-staged cases but age and baseline respiratory function were not significantly different from non-NAC group. Interval between first and second spirometry was 31 days for non-NAC group, 69 days for NAC group. After exercise, non-NAC group showed significant improvement in VC (3135 to 3600ml, P  = 0.006), FEV1.0 (2255 to 2565ml, P  = 0.004), whereas NAC group showed little change in VC (3560 to 3630ml, P  = 0.514), FEV1.0 (2585 to 2555ml, P  = 0.514). Postoperative complication occurred in 27 of 52 cases. Postoperative pneumonia occurred in 7 (13.5%) in the present cohort, which was less frequent than 42% in the historical control cohort without breathing exercise. Conclusion Preoperative breathing exercise with Coach 2 improved respiratory function in patients without NAC. In patients with NAC, the effect of exercise was smaller than non-NAC group, still exercise might suppress the decrease of respiratory function during NAC. Breathing exercise may reduce postoperative pulmonary complications. Disclosure All authors have declared no conflicts of interest. [ABSTRACT FROM AUTHOR]