eHealth support for oncological therapy management has different faces. In addition to the direct support of therapy-supportive measures such as the promotion of physical activities, monitoring of the diet and observation of the quality of life through eHealth approaches are possible. Many solutions are now in transition between research and routine use. The most substantial evidence today is in the area of symptom monitoring. Independent studies have shown a significant survival benefit among other advantages as well. There is also a good overlap in eHealth and physical activity. More and more solutions are coming onto the market, which also has an impact for cancer patients. In the field of nutrition, there are only a few successful approaches both within and outside oncology. In contrast, the application of eHealth for the detection of disease-related malnutrition seems promising. Innovative approaches involving “artificial intelligence” or “Internet of Things” are slowly finding their place in both research and routine. For routine care, it will be necessary for doctors, nurses, and patients to know what a real medical eHealth application is and which are just lifestyle products without the needed quality for professional medical usage.