Abstract Cancer is a common disease with significant impact on patients and society. Cancer and oncological treatment can negatively affect muscle, and muscle health impacts oncologic outcomes. This review studied the effect of different muscle parameters on oncologic outcomes. A systematic search was performed until April 2023. Parameters included were muscle thickness, cross-sectional area, skeletal muscle index, skeletal muscle mass, pennation angle, fascicle length, muscle density, echo intensity and elastography. Imaging methods included were computerized tomography, magnetic resonance imaging, ultrasound and dual-energy X-ray absorptiometry. Outcome parameters assessed were survival, chemotoxicity, surgical outcome, treatment response, duration of hospitalization, and quality of life. This review included 117 articles. Individuals with reduced skeletal muscle index or muscle density had lower survival rates, higher chemotoxicity and surgical complications, more hospitalizations, less treatment response and lower quality of life. Reduced muscle quantity and quality can impact oncological outcomes, either through primary or secondary sarcopenia. These findings warrant the need for holistic assessment by using comprehensive geriatric assessment to establish a correct treatment dosage. These results also suggest a beneficial effect of exercise and nutritional support. Further research can be useful to better understand the underlying mechanisms and optimize specific treatments for muscle in oncological patients.