Stress-related increased cortisol production by the adrenal glands is normal and physiological, and does not lead to Cushing's syndrome. It can be produced by prolonged, high doses of corticosteroid medications and can also result from adrenal gland tumors producing abnormally excessive amounts of cortisol. One other cause is excessive stimulation of the adrenal glands to produce cortisol by high levels of ACTH hormones secreted by a diseased pituitary gland or other abnormal glands. Excerpt from http://www.urologyhealth.org/search/index.cfm?topic=43&search=cancer&searchtype=and

The symptoms, disabilities and lifestyle of a person with Cushing's syndrome (CS) depend on the degree of cortisol excess, the duration of the disease, the basic health of the person and especially the type and curability of the syndrome. If it is cured, all of the features of the disease can subside, but this may take as long as two to 18 months. During that time, most people get annoyed and frustrated by the slow improvements in physical changes. The combination of CS and adrenal insufficiency signs and symptoms (e.g., dizziness, weakness, nausea and loss of appetite) decrease as replacement steroid hormones are tapered and adrenal hormone production slowly improves toward normal. Frequent calls and visits to a physician are necessary. If the CS is curable, or if medically-induced CS remains, these individuals will have to cope with persistent fatigue, muscle weakness, abdominal and facial weight gain, depression, mood swings and all the other signs and symptoms mentioned earlier. Regular visits to a physician for examinations, blood tests and treatments of infections and complications will be necessary and are often viewed as a severe burden. Excerpt from http://www.urologyhealth.org/search/index.cfm?topic=43&search=cancer&searchtype=and