When defining the aims of physical activity in cancer patients, the following four levels need to be regarded: the physical, psychological, social, and educative level of the patient. These four aims apply to all cancer patients whether they are in the acute and rehabilitation phase or take part in a home-based program. Yet, the evidence evaluation, regarding the different aims of physical exercise, still varies considerably. Meaningful reviews with various entities indicate that physical activity can reduce the loss of power, counteract cancer related cachexia, reduce treatment-related side effects (nausea, vomiting, and pain), and improve general performance. In addition, physical active patients experience a psychophysical stabilization, including a reduction in depression and anxiety and an increase in confidence. Further research has shown that a targeted and controlled exercise therapy improves quality of life, reduces fatigue, and inhibits the inactivity-induced loss of function in oncological patients. Finally, an increased level of activity reduces the risk of comorbidities such as the metabolic syndrome [3–8, 10, 11, 14, 16].

A central and daily question regarding therapeutic exercising with oncological patients is: When to start with the exercise program? In the clinical setting, the trend is to involve exercise therapy as early as possible. The aim here is prevention and stabilization. The loss of power, for example, resulting from the long hospital stay and inactivity can be hampered. Thus, exercise therapy not only has rehabilitative aims but also includes preventive aspect, since a major (health) problem is also the lack of exercise. Exercise therapy should therefore start as early as possible, i.e., already during the medical treatment of cancer [14].

The aim of therapeutic exercises in the curative and palliative phase: Prevention of negative physical and psychological consequences and psychosocial stabilization.

Exercise therapy continues within the rehabilitation center and is then carried on within a rehabilitation sports program in a cancer sports group. In case the participation in a sports group is not possible or not wanted, patients are recommended to exercise individually in order to stay active all their life.

Ideally, patients in the rehabilitation center receive exercise-related diagnostics to determine whether moderate or more intensive physical activities are feasible. Furthermore, the obtained data enables the determination of the exercise therapy’s intensity and volume. Yet, the entire medical history, current medication, but also the sporting experiences must be considered, as well as the patient’s personal preferences. In order to ensure a targeted-oriented therapy, unsettled questions must be answered at an early stage. A patient will only continue to exercise individually at home, if he/she enjoys his/her activity and feels safe.

The aim of therapeutic exercises in the rehabilitation phase: Regeneration of physical and mental components and psychosocial stabilization or improvement.

In general, there are still a whole range of subjects that have not been (sufficiently) examined in the field of “cancer and exercise”. Only recently, the study question of individualized training control arose. Clearly, different and individualized training programs, depending on cancer entity, medical treatment, and patients’ deficits, are necessary. In addition, the large field of palliative care has hardly been studied so far. An increasing number of patients that cannot be cured of their disease will live longer with cancer. In this context, physical activity has the ability to enrich the improved quantity of life with a corresponding quality. Further, sports medical diagnostics for cancer patients, including specific assessments or valid instruments, is another important field. Meaningful data to determine the endurance performance by means of spiroergometry are, for example, still missing [2]. In this context, we need to conduct further studies in order to improve the scientific statement and to optimize exercise therapy in oncology.