Sensitive circulating tumor DNA-based residual disease detection in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is one of the leading causes of cancer-related death in women worldwide, and is characterized by a high rate of recurrence after surgery and chemotherapy. We sought to implement a circulating tumor DNA (ctDNA)-based blood test for more accurate post-operative surveillance of this disease. We analyzed 264 plasma samples collected between June 2016 and September 2021 from 63 EOC patients using tumor-guided plasma cell-free DNA analysis to detect residual disease after treatment. Assay specificity was verified using cross-patient analysis of 1,195 control samples. ctDNA was detected in 51 of 55 (93%) samples at diagnosis, and 18 of 18 (100%) samples at progression. Positive ctDNA in the last on-treatment sample was associated with rapid progression (median 1.02 versus 3.38 yr, HR = 5.63, P < 0.001) and reduced overall survival (median 2.31 versus NR yr, HR = 8.22, P < 0.001) in patients with high-grade serous cancer. In the case of 12 patients, ctDNA assays detected progression earlier than standard surveillance, with a median lead time of 5.9 mo. To approach the physical limits of ctDNA detection, five patients were analyzed using ultra-sensitive assays interrogating 479-1,856 tumor mutations, capable of tracking ctDNA fractions down to 0.0004%. Our results demonstrate that ctDNA assays achieve high sensitivity and specificity in detecting post-operative residual disease in EOC.

Solitary brain metastasis: results of an RTOG/SWOG protocol evaluation surgery + RT versus RT alone

From 1983 through 1986, the Southwest Oncology Group and Radiation Therapy Oncology Group conducted an intergroup study designed to evaluate the effectiveness of surgical resection in those patients with solitary central nervous system (CNS) metastases. The study was initially designed as a prospective randomized trial. Because of difficulty accruing patients, the registration format was altered and the patients were placed on study according to physician preference. Ninety-seven patients were registered on study and 80 patients were eventually analyzed. Fifty-five patients underwent radiation therapy alone and 25 patients received surgery and radiation. Fifty-nine percent of those patients undergoing radiation therapy alone improved or stabilized while 79% of those patients undergoing surgery and radiation therapy improved or stabilized. Eventually, 22% of the surgically treated patients failed in the brain while 45% of the patients undergoing radiation therapy exhibited a CNS relapse. Survival was improved when corrected for other prognostic factors in those patients undergoing surgical resection. Although not a prospective randomized trial, this study does suggest an improvement in the survival of a select group of patients able to tolerate neurosurgical resection.