Background: Numerous studies have shown that cell-free DNA (cfDNA) levels may serve as a non-invasive biomarker of a broad spectrum of acute and chronic pathologies. However, in order to make clinical decisions based on cfDNA measurements, it is essential to understand the magnitude of biological variation so this variation is not confused with a variation that actually represent a clinically relevant change. The present study was designed to evaluate the biological variation of cfDNA in healthy subjects and lung cancer patients. Methods: Plasma samples were collected from 33 healthy subjects and ten lung cancer patients over three days, as well as during the same day. CfDNA was quantified using droplet digital PCR. Biological variation data was estimated using mixed models. Findings: The within-subject variation was 25% and the between-subject variation was 30%. The reference change value for the healthy subjects was 70%. There was no systematic difference in cfDNA levels from day-today (p = 0 61), but there was a significant decline during the day (p < 0 01). The within-subject variation in cancer patients was comparable to healthy subjects, whereas the between-subject variation was much larger (139%). No systematic differences from day-today were observed for the cancer patients (p > 0 3). Interpretation: Our findings show that cfDNA levels fluctuate significantly during the day and exhibit considerable within-subject variation. Thus, the data presented offer a substantial contribution to the interpretation of the clinical significance of cfDNA. Funding: Laege Sofus Carl Emil Friis og hustru Olga Doris Friis' Legat, Harboefonden, and Dagmar Marshalls Fond.

Circulating tumour DNA (ctDNA) has been increasingly incorporated into the treatment of cancer patients. ctDNA is generally accepted as a powerful diagnostic tool, whereas the utility of ctDNA to monitor disease activity needs to be fully validated. Central to this challenge is the question of whether changes in longitudinal ctDNA measurements reflect disease activity or merely biological variation. Thus, the aim of this study was to explore the intra‐individual biological variation of ctDNA in lung cancer patients. We identified tumour‐specific mutations using next‐generation sequencing. Day‐to‐day and hour‐to‐hour variations in plasma concentrations of the mutant allele and wild‐type cell‐free DNA (cfDNA) were determined using digital PCR. The levels of the mutant alleles varied by as much as 53% from day to day and 27% from hour to hour. cfDNA varied up to 19% from day to day and up to 56% from hour to hour, as determined using digital PCR. Variations were independent of the concentration. Both mutant allele concentrations and wild‐type cfDNA concentrations showed considerable intra‐individual variation in lung cancer patients with nonprogressive disease. This pronounced biological variation of the circulating DNA should be investigated further to determine whether ctDNA can be used for monitoring cancer activity.

MiR-30b, miR-30c, miR-221 and miR-222 are known to induce gefitinib resistance in lung cancer cell lines with activation of mutations in the epidermal growth factor receptor (EGFR). However, the role of these four microRNAs in tyrosine kinase inhibitor (TKI)-resistance in non-small cell lung cancer (NSCLC) patients is unknown. Thus, the aim of this study was to investigate the predictive value of miR-30b, miR-30c, miR-221 and miR-222 in plasma from EGFR-mutated lung cancer patients receiving erlotinib. Materials and methods: The cohort consisted of 29 EGFR-mutated lung cancer patients receiving erlotinib. Plasma levels of miR-30b, miR-30c, miR-221 and miR-222 were analyzed by qPCR from blood samples collected before treatment start. Plasma concentration of each microRNA was correlated to clinical outcome. Results: Plasma concentrations of miR-30b and miR-30c could be determined in all 29 patients. Low plasma concentrations of miR-30b and miR-30c showed significant correlation with superior progression-free survival (PFS) (miR-30b: HR = 0.303 [0.123-0.747], p < 0.05; miR-30c: HR = 0.264 [0.103-0.674], p < 0.05). Low plasma concentrations of miR-30c were also significantly correlated with superior overall survival (OS) (HR = 0.30 [0.094-0.954], p < 0.041). Conclusion: High plasma concentrations of miR-30b and miR-30c predicted shorter PFS and OS. This implies that miR-30b and miR-30c could have clinical potential as biomarkers in EGFR-mutated lung cancer patients.

Background The demand for gender-affirming hormone therapy is increasing worldwide prompting a growing requirement for solid evidence for efficacy and safety. Aim We aimed to report on the organization of transgender care and the current clinical practice of feminizing hormone therapy in specialized clinics in the Nordic countries. Methods This study was a cross-sectional study performed as a questionnaire survey. A quantitative questionnaire was sent to 15 specialized clinics prescribing feminizing hormone therapy in the Nordic countries. Outcomes Twelve clinics responded to the inquiry. RESULTS The answers showed great variance in both number of clinics in each country as well as number of doctors responsible for prescribing gender-affirming hormone therapy. There was great difference in the width of the target ranges for estrogen plasma concentrations and in preferred route of administration for estrogens. Likewise, the risk assessment and monitoring of side effects were diverse. Clinical Implications To gather solid data on efficacy and safety of feminizing hormone therapy, the treatment regimens and the recording of side effects need to be consistent across the clinics responsible for the treatment of transfeminine patients. Strenghts & Limitations: This is to our knowledge the first report on treatment regimens for feminizing hormone treatment in the Nordic countries. The response rate was 80%; however, the included clinics only cover approximately 30% of the expected numbers of transfeminine individuals. CONCLUSION Despite the great diversity across clinics as regard to organization of clinics and to treatment regimens, the vast majority of clinics operated within the guidelines defined by The Endocrine Society.

Cancer patients face an elevated risk of bleeding, and here platelets play a pivotal role. The association between platelet count and bleeding, as well as safe thresholds for prophylactic platelet transfusion, is described mainly in hematological malignancies, and knowledge is sparse for patients with solid tumors. Platelet function tests may further improve bleeding risk assessment in cancer patients. This study provides a systematic review of the available literature on associations between platelet count and/or function and bleeding in adult cancer patients. The review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. PubMed, Embase, and Web of Science were searched up to August 2019. The National Heart, Lung, and Blood Institute's tools were used for quality assessment. In total, 52 studies investigated associations between bleeding and platelet count (n = 40) or function (n = 12) in patients with hematological malignancy (n = 31), solid tumors (n = 11), or both (n = 10). The majority of included studies rated good (n = 23) or fair (n = 25). The association between platelet count and bleeding was most pronounced at platelet counts ≤ 10 × 109/L but was less evident for solid tumors. Overall, reduced platelet function was significantly associated with bleeding risk. Thus, the available evidence supports current guidelines for prophylactic platelet transfusions at platelet count ≤ 10 × 109/L in hematological cancer patients, whereas more evidence is needed in patients with solid tumors. Platelet function analysis may be valuable in assisting bleeding risk assessment in cancer patients but is sparsely investigated so far.