Current literature reveals a significant gap in understanding how tiredness and fatigue in cancer patients should be defined and measured. Research indicates conceptual and measurement discrepancies (Piper 1993), with no universally accepted continuum of tiredness or fatigue. For instance, what does it mean when patients indicate they feel "very tired" on a visual analogue scale? Is this a reflection of their overall well-being or a measure of their quality of life (Hiirny and Bernhard 1993)? English literature often uses "fatigue" to denote extreme tiredness, suggesting that in English, unusual or persistent tiredness is categorized as fatigue rather than mere tiredness. Conversely, in German, "tiredness" (Müdigkeit) does not inherently imply distress linked to illness or unusual effort. However, it becomes distressing when it disrupts the balance between rest and activity, manifesting as excessive tiredness unrelated to exertion (Piper 1993). Since there is no direct translation for "fatigue" in German, the term "extreme, unusual tiredness" (extreme, unübliche Müdigkeit) is used to convey the concept. This distinction is crucial for ensuring that future fatigue research in German-speaking regions can be effectively compared with studies conducted elsewhere.
