Background: It is unclear how symptoms reported by an electronic patient-reported outcomes (ePRO) tool compare to symptoms reported to triage nurses by patient-initiated telephone calls. This work describes symptoms reported using each of these methods, and the percent of patients requiring an acute office visit triggered by these symptom reports. Methods: Among patients diagnosed with breast, lung, or colon cancer at three community oncology practices from 2020 to 2023, we examined ePRO symptom reports and compared these with symptoms reported via telephone triage to nurses by patients not using the ePRO tool. Results: 3,509 patients reported symptoms by ePROs, and 9,071 patients only reported by phone. Among patients reporting by ePRO, 2,162 submitted both ePROs and used telephone triage services. The most common symptoms that patients reported by ePRO reports (47,284 reports) were weakness / fatigue (72.9% of patients), pain (62.0%), nausea (39.2%), and headache (33.1%). The most common symptoms that patients reported by phone reports (19,344 reports) were pain (32.9%), weakness / fatigue (13.4%), swelling (11.1%), cough (10.3%), and diarrhea (9.4%). The median number of reports in the ePRO group was 6.0 (mean 13.5, IQR: 2.0, 15.0) per patient and the median number of reports in the phone triage group was 1.0 (mean 2.1, IQR: 1.0, 2.0) per patient. The most common high-urgency symptoms in the ePRO group (defined by practice defined symptom threshold) were weakness / fatigue (67.2% of patients), pain (55.7%), headache (40.2%), nausea (32.0%), and difficulty breathing (29.2%), while the most common high-urgency symptoms (as determined by the triage nurse) in the phone triage group were pain (32.4%), weakness / fatigue (11.8%), swelling (11.4%), fever/chills (10.1%), and cough (9.7%). More patients reported high-urgency symptoms by ePRO (n = 1,873, 53.4%) compared to those reported by phone triage (n = 2,448, 27.0%). Of patients in the ePRO group with a severe symptom who visited a site with acute care visits data, 330 patients (45.4%) had an acute care visit within 72 hours of a symptom report compared to 745 patients (47.5%) in the telephone triage group. Conclusions: Patients using ePROs reported more symptoms than patients reporting by phone, possibly because electronic reporting allows patients to easily communicate symptoms to care providers and receive prompt attention. Pain and weakness/fatigue were the most common urgent symptoms in both groups. The need for an acute care visit was the same in both groups. Further refinement of the ePRO tool including standardization of symptom thresholds, more uniform implementation in practices, and patient education with respect to optimal use of the ePRO may enable practices to replace telephone triage with ePROs.