Early detection of cancers through the analysis of ctDNA could have a significant impact on morbidity and mortality of cancer patients. However, using ctDNA for early cancer diagnosis is challenging partly due to the low amount of tumor DNA released in the circulation and its dilution within DNA originating from non-tumor cells. Development of new technologies such as droplet-based digital PCR (ddPCR) or optimized next generation sequencing (NGS) has greatly improved the sensitivity, specificity and precision for the detection of rare sequences. Areas covered: This paper will focus on the potential application of ddPCR and optimized NGS to detect ctDNA for detection of cancer recurrence and minimal residual disease as well as early diagnosis of cancer patients. Expert commentary: Compared to tumor tissue biopsies, blood-based ctDNA analyses are minimally invasive and accessible for regular follow-up of cancer patients. They are also described as a better picture of patients' pathology allowing to highlight both tumor heterogeneity and multiple tumor sites. After a brief introduction on the application of the follow-up of ctDNA using genetic or epigenetic biomarkers for prognosis and surveillance of cancer patients, potential perspectives of using ctDNA for early diagnosis of cancers will be presented.

Seroma or lymphocele remains the most common complication after mastectomy and lymphadenectomy for breast cancer. Many different techniques are available to prevent this complication: wound drainage, reduction of the dead space by flap fixation, use of various types of energy, external compression dressings, shoulder immobilization or physical activity, as well as numerous drugs and glues. We searched MEDLINE, clinicaltrials.gov, Cochrane Library, and Web of Science databases for publications addressing the issue of prevention of lymphocele or seroma after mastectomy and axillary lymphadenectomy. Quality was assessed using Hawker’s quality assessment tool. Incidence of seroma or lymphocele were collected. Fifteen randomized controlled trials including a total of 1766 patients undergoing radical mastectomy and axillary lymphadenectomy for breast cancer were retrieved. The incidence of lymphocele or seroma in the study population was 24.2% (411/1698): 25.2% (232/920) in the test groups and 23.0% (179/778) in the control groups. Neither modification of surgical technique (RR 0.86; 95% CI [0.72, 1.03]) nor application of a medical treatment (RR 0.96; 95% CI [0.72, 1.29]) was effective in preventing lymphocele. On the contrary, decreasing the drainage time increased the risk of lymphocele (RR 1.88; 95% CI [1.43, 2.48). There was no publication bias but the studies were of medium to low quality. To conclude, despite the heterogeneity of study designs, drainage appears to be the most effective technique, although the overall quality of the data is low.