Observational research can impact clinical decision making for cancer treatment by providing real-world evidence to complement randomized controlled trials, which have limitations. Observational studies capture long-term outcomes of various treatments in everyday practice. However, their findings are more susceptible to bias. To strengthen observational research, standards are needed for electronic health data collection and reporting, while prioritizing patient privacy and rigorous methodologies. With these improvements, observational data can better inform estimates of cancer progression and treatment effects.