The diagnosis and treatment of cancer are associated with impairment at the physical and at psychological level. In addition, side effects are a potentially treatment-limiting factor that may necessitate dose reduction, delay, or even discontinuation of therapy, with negative consequences for outcome and mean survival. Numerous studies have shown that physical activity and sports and exercise therapy programs are not only practicable but also recommendable for oncologic patients during the acute phase and in the aftercare. Furthermore, nutrition plays an important role in all stages of tumor therapy. A timely integration of a nutrition therapy and physical activity in the form of physiotherapy and sports therapy serves to prevent and reduce treatment-associated side effects. Evidence-based recommendations on cancer prevention through nutrition therapy, physical activity, and sports and exercise therapy should be integrated into treatment plans for oncology patients as well as in health care services for the general population. Individual counselling by trained nutrition and exercise specialists may be advisable to receive concrete recommendations on the respective tumor entity or specific side effects. This mini review is based on a selective literature search in the PubMed database and Cochrane Central Register of Controlled Trials on the subjects of healthy diet and physical activity in primary prevention and follow-up about cancer.