Cancer treatments can have profound effects on a patient's mood. Chemotherapy, for instance, can lead to "chemo brain," a condition characterized by cognitive impairment and emotional lability. Radiation therapy can also cause fatigue and mood swings. Furthermore, medications like steroids, often used to manage side effects, can exacerbate emotional fluctuations. Hormonal therapies, particularly for cancers like breast and prostate cancer, can disrupt hormone levels, leading to mood changes.