Background: Patient-reported outcomes (PROs) are increasingly valued as a key tool in patient-focused treatment decisions. However, a lack of standardization leads to significant variability in PRO collection and reporting in ground-breaking clinical trials of novel agents. We sought to characterize the mechanisms of assessment and variability by which PROs are reported for newly approved anti-cancer therapies. Methods: We reviewed the U.S. Food and Drug Administration (FDA) approvals between 2011 and 2017 for anti-cancer new molecular entities (NMEs) and new biologic approvals (BLAs). For each therapy, the pivotal clinical trial leading to FDA approval was identified using the national clinical trial (NCT) number and assessed for inclusion of PROs. A separate PubMed search was conducted to evaluate for PRO publication distinct from the original trial based on national clinical trial registry number. Results: From 2011 to 2017, the FDA approved 66 NMEs/BLAs based on 74 clinical trials for cancer treatment. Of the 74 clinical trial publications, 21 (28%) of the trials published PRO data in their original clinical publication, 18 (24%) published a separate PRO analysis, and 35 (47%) did not publish PRO data in either format. Among the 32 clinical trials (43%) that listed PROs as pre-specified outcomes, 72% published PROs (23/32). The separate PRO analyses (N = 18) were published considerably later following FDA approval (mean 605 days) than the original clinical trials (mean 20 days, N = 74, P < 0.001). Conclusions: As cancer treatment options expand, therapy decisions become increasingly nuanced. PROs assist decision-making by providing detailed information on important aspects of quality of life and tolerability. Our research has identified a significant lag in the publication of companion studies of PRO data associated with pivotal clinical trials, representing a meaningful gap in information critical to patients and oncologists in the process of making informed decisions.