Background: Inclusion of PROs in RCTs involving elderly cancer patients may be particularly important, as the elderly are often frail and vulnerable, and treatment decisions need to carefully balance potential burden against benefit. We aimed to determine how many RCTs involving elderly patients have included a PRO endpoint, and identified the most relevant PRO information available in this area. Methods: A systematic review in PubMed/Medline and Cochrane Library identified RCTs with PRO endpoint that enrolled a cancer sample (breast, colorectal, lung, prostate, gynaecological and bladder cancer) with a mean/ median age ≥70 years, published from January 2004 to June 2018. The quality of PRO reporting was evaluated using the ISOQOL-PRO recommended criteria. Two reviewers independently performed data extraction. RCTs meeting at least two-thirds of the recommended criteria were considered as “probably-robust” and therefore most likely to be able to inform patient care. Results: Out of the 610 RCTs with PRO endpoint identified, only 67 RCTs (11%) enrolled a sample that met the above criteria. In 19 RCTs (28.4%) PROs were the primary endpoint and 35 RCTs (52.2%) were conducted in a metastatic population. Less than one-third of these trials (n = 21) were considered as probably-robust. In 10 (47.6%) out of the 21 probably-robust RCTs, PROs favored the experimental arm and in 8 (38.1%) the arms did not differ. Overall survival (OS) was an endpoint in 13 of the probably-robust RCTs. In only 3 of these RCTs (23.1%) did OS improve in the experimental arm and in 10 (76.9%) there was no difference in OS between arms. In about half of the probably-robust trials evaluating OS (n = 7, 53.8%), PROs provided information that contrasted with survival findings. In two RCTs, OS improved in the experimental arm, while PROs either did not change between arms (n = 1) or favoured the control arm (n = 1). Conversely, in 5 RCTs (38.5%), OS did not differ between arms whereas PROs favoured the experimental arm. Conclusions: Among cancer RCTs including PROs, the proportion of those conducted in the elderly is low. However, PRO data may provide useful information for these type of patients and their clinicians.