Does persistent fatigue in survivors relate to cancer?

In-depth investigations of the causes and contributing factors of persistent fatigue in long-term cancer survivors are scarce and fewer than 20 reports have focused on lymphoma survivors, including limited cross-sectional descriptive studies.7 No medical explanation exists for why fatigue develops or persists in some patients, and the findings of Kreissl and colleagues2 suggest that persistent fatigue is not related to disease or treatment. [...]psychological factors (eg, susceptibility to anxiety or depression) or biological factors such as immunocompetence8 or heritable genetic variations (eg, chemotherapy drug metabolism genetic polymorphisms9) might be playing a part.