e14556 Background: Circulating tumor DNA (ctDNA) technology allows for monitoring the genomic profile of cancer over time non-invasively, and in a way that is more representative of existing tumor clones than tissue sampling. The clinical and research applications of this new technology are numerous, and they are potentiated through serial ctDNA testing of individual patients. It is important to identify and characterize real-world data sets that will permit the development of both ctDNA’s clinical and research applications. Methods: This is an observational study of breast, non-small cell lung cancer (NSCLC), colorectal and prostate cancer patients who had ctDNA testing in The US Oncology Network from August 2014 to August 2023. All unique ctDNA reports per patient were collected, along with the report dates and patient characteristics. Rate of change in number of unique reports per month through time was evaluated as well as frequencies of serial testing and median time lapse between diagnosis and date of first ctDNA test by cancer type. Results: Number of new unique ctDNA testing reports per month increased for The US Oncology Network from 2014 through 2018 at a rate of 0.86 (95% CI [0.70, 1.02]). From 2018 to 2023 this rate increased to 5.87 (95% CI [5.16, 6.59]) new reports per month. The total number of unique patients with one of the 4 cancer indications and at least one ctDNA test during the study time period was 10,852. The cancer indication with greatest number of patients with ctDNA testing is NSCLC with 5,503 patients, followed by breast with 2,408, and colorectal and prostate with 1,544 and 1,397 respectively. Black patients were equally represented across all 4 cancers at rates of 13.6% for colorectal, 12.7% for breast, and 12% for NSCLC and prostate. Patients over 65 made up 66% for prostate and NSCLC but only 38% and 32% for colorectal and breast respectively. Most patients presented with a single ctDNA test (n = 9482), but an important proportion presented with 2 serial ctDNA tests or more (n = 1370, 12.6%).The median time between either cancer diagnosis date or date of first visit in The Network and the date of the first ctDNA test report was 39 days for NSCLC, 1,690 days for breast, 377 days for colorectal and 772 days for prostate, and presented with a skewed, long right tailed distribution. Median times were similar for Black and White patients across all cancers. Conclusions: The number of patients with ctDNA testing data available is increasing through time without evidence of plateauing. Although the total number of patients represented is still a very small fraction of the total patient population, the rate of increase in number of new reports through time is equivalent to an exponential increase in the total number of reports. 12.6% of patients presented with two tests or more, potentially allowing for pre and post treatment assessments. There’s an opportunity to better align cancer research and cancer treatment paradigms with this new technology.

Pan-tumor circulating tumor DNA testing in the community oncology setting.