Background: Despite increased molecular testing (MT) for cancers with actionable biomarkers, the NCCN guidelines only recommend comprehensive MT for newly diagnosed patients with metastatic non-small cell lung cancer (mNSCLC). Methods: We used IBM MarketScan Claims to examine MT and Tx use among privately insured patients < 65 yrs. We identified 101,456 patients with new colorectal, lung, breast, ovary, or prostate cancers or melanoma between 2017-2019. We used procedure codes to identify MT receipt within 6 months after the cancer diagnosis. We divided MTs into three categories: single-gene, panel, or unspecified MTs (tests without a uniquely assigned procedure code). We also identified the use of targeted therapy in the year after the cancer diagnosis. Results: Among 101,456 patients, 14,657 (14.4%) received MT, and 8,166 (8.0%) received targeted therapy. Use patterns varied across cancers (Table). Patients with breast, colorectal, or ovary cancers were more likely to receive MT. Patients with lung cancer were most likely to receive panel tests. Patients with breast cancer were most likely to receive single-gene tests. Patients with lung cancer were the most likely to receive targeted therapy, with or without MT. Median days from diagnosis to MT was the shortest for lung cancer and the longest for prostate cancer. Median days from diagnosis to targeted therapy was the shortest for lung cancer and the longest for ovary cancer. Conclusions: We observed higher uptake of MT among individuals with lung cancer, consistent with recent guidelines. However, the high use of single-gene tests among patients with lung cancer, the receipt of targeted therapy without MT among patients with breast or lung cancers, and the use of multiple types of MT might suggest poor quality of care. Moreover, despite multiple actionable biomarkers, the uptake of MT was low in other cancers. Patients with other cancers might not benefit from the advances of cancer precision medicine due to the lack of clear guidelines.