COVID-19 Test Strategy to Guide Quarantine Interval in University Student

ABSTRACTBACKGROUNDFollowing COVID-19 exposure, the CDC recommends a 10-14 day quarantine for asymptomatic individuals and more recently a 7 day quarantine with a negative PCR test. We performed a university-based prospective student cohort study to determine if early PCR negativity predicts day 14 negativity.METHODSWe enrolled 101 asymptomatic, quarantining, students, performed nasopharyngeal swabs for viral testing on days 3 or 4, 5, 7, 10 and 14 and determined the proportion of concordant negative results for each day versus day 14 with a two-sided 95% exact binomial confidence interval.RESULTSOverall, 14 of 90 (16%, 95% CI: 9% - 25%) tested positive while in quarantine, with 7 initial positive tests on day 3 or 4, 5 on day 5, 2 on day 7, and none on day 10 or 14. Rates of concordant negative test results are: day 5 vs. day 14 = 45/50 (90%, 95% CI: 78% - 97%); day 7 vs. day 14 = 47/52 (90%, 95% CI: 79% - 97%); day 10 vs. day 14 = 48/53 (91%, 95% CI:79% - 97%), with no evidence of different negative rates between earlier days and day 14 by McNemar’s test, p > 0.05.CONCLUSIONSThe 16% positive rate supports the ongoing need to quarantine close contacts of COVID-19 cases, but this prospective study provides the first direct evidence that exposed asymptomatic students ages 18-44 years in a university setting are at low risk if released from quarantine at 7 days if they test negative PCR test prior to release.

Breast cancer overdiagnosis in stop-screen trials: More uncertainty than previously reported

Objective According to the Independent UK Panel on Breast Cancer Screening, the most reliable estimates of overdiagnosis for breast cancer screening come from stop-screen trials Canada 1, Canada 2, and Malmo. The screen-interval overdiagnosis fraction is the fraction of cancers in a screening program that are overdiagnosed. We used the cumulative incidence method to estimate screen-interval overdiagnosis fraction. Our goal was to derive confidence intervals for estimated screen-interval overdiagnosis fraction and adjust for refusers in these trials. Methods We first show that the UK Panel’s use of a 95% binomial confidence interval for estimated screen-interval overdiagnosis fraction was incorrect. We then derive a correct 95% binomial-Poisson confidence interval. We also use the method of latent-class instrumental variables to adjust for refusers. Results For the Canada 1 trial, the estimated screen-interval overdiagnosis fraction was 0.23 with a 95% binomial confidence interval of (0.18, 0.27) and a 95% binomial-Poisson confidence interval of (0.04, 0.41). For the Canada 2 trial, the estimated screen-interval overdiagnosis fraction was 0.16 with a 95% binomial confidence interval of (0.12, 0.19) and a 95% binomial-Poisson confidence interval of (−0.01, 0.32). For the Malmo trial, the estimated screen-interval overdiagnosis fraction was 0.19 with a 95% binomial confidence interval of (0.15, 0.22). Adjusting for refusers, the estimated screen-interval overdiagnosis fraction was 0.26 with a 95% binomial-Poisson confidence interval of (0.03, 0.50). Conclusion The correct 95% binomial-Poisson confidence interval s for the estimated screen-interval overdiagnosis fraction based on the Canada 1, Canada 2, and Malmo stop-screen trials are much wider than the previously reported incorrect 95% binomial confidence intervals. The 95% binomial-Poisson confidence intervals widen as follow-up time increases, an unappreciated downside of longer follow-up in stop-screen trials.

NEXT: A phase II, open-label study of nivolumab adjuvant to chemoradiation in patients (pts) with localized muscle invasive bladder cancer.

TPS605 Background: In pts with localized muscle invasive bladder cancer (MIBC), trimodality bladder preserving therapy (TMT), with transurethral resection of bladder tumor, radio-sensitizing chemotherapy and definitive radiation, has up to a 50% risk of local and systemic relapse during the 2-year post treatment phase. We hypothesize that by inhibiting immune checkpoints, chemo-radiation induced tumor specific immune response will be enhanced both locally and abscopally, resulting in better failure-free survival (FFS). In the NEXT trial, we evaluate the efficacy of nivolumab after completion of the TMT in this setting. Methods: Pts with localized MIBC who have completed standard TMT are eligible. Pts receive nivolumab 480 mg intravenously every 4 weeks for up to 12 doses. Treatment with nivolumab begins within 90 days of completion of TMT. Subjects undergo surveillance cystoscopic and scan based assessments on study. Archived tumor tissue at baseline and at relapse is obtained for correlative studies. The primary endpoint is 2-year FFS. Secondary endpoints include FFS at 2 years in patients with intact bladder, rate of radical cystectomy (RC), cystoscopic local control, distant FFS in patients with intact bladder and those that undergo RC, overall survival, toxicity and quality of life. Exploratory endpoints include to characterize changes in immune cell subsets that can be correlated with clinical outcome and to assess the correlation of response to PD-L1 expression in pretreatment tumor tissue in the study subjects. The planned sample size for this single arm, open label trial is 28 pts. Kaplan-Meier methods will be used to plot survival endpoints and cystoscopic local control rates. Exact binomial methods will be used to provide 6 months, 1-year and 2-year estimates for these endpoints. The sample size justification is based on the maximum width of a two-sided 95% binomial confidence interval for 2 year FFS. With 28 evaluable subjects, a 95% exact binomial confidence interval, estimated using the method of Clopper-Pearson, will extend no more than 20% from the observed FFS. Clinical trial information: NCT03171025.

Optimizing Tissue Use: A Step-wise Approach to Diagnosing Squamous Cell Lung Carcinoma on Small Biopsies

Background: Histologic subtyping of lung cancer has significant implications for treatment planning. Accurate diagnosis based on cytology/small biopsy specimens is challenging and frequently determined by morphology, as material is often not sufficient for immunohistochemical studies (IHC). We investigated the concordance between the rates of diagnosis from cytology/small biopsies compared with surgical specimens in patients with squamous cell lung cancer (SCC) and the utility of IHC for diagnostic precision in lung cancer subtyping. Methods: We conducted a 5-year retrospective analysis identifying cases of SCC diagnosed on cytology/small biopsies ± IHC and compared them with subsequent surgical specimens when available. The number of patients with SCC on surgical biopsy and the concordance between cytology ± IHC was determined. Results: Over the 5-year period (2011-2015), 231 cases were identified. Surgery was performed on 66 cases (28.5%), of which 87.9% concurred with cytological diagnosis (95% exact binomial confidence interval [CI] = 77.5%-94.6%). There were 36 cases diagnosed in 2014 and 2015 with IHC data. Of those cytology cases with IHC (n = 12), SCC was confirmed by surgery in 91.7% (95% CI = 61.5%-99.8%). Of those without IHC (n = 24), 95.8% were confirmed SCC by surgery (95% CI = 78.9%-99.9%). These rates were not different (Fisher exact test). All cases with IHC were morphologically squamous. Conclusions: Our data demonstrate that diagnostic precision of identifying SCC by cytology/small biopsy is comparable with or without additional IHC studies. We recommend judicious use of IHC on cytology specimens, reserving it for cases where cytomorphology is equivocal. Tissue should be preserved for molecular analysis, which may have therapeutic implications.