Can guided imagery help cancer patients cope with chronic pain?

Yes. Guided imagery and hypnotherapy can also change how our brain processes pain. The experience of pain is related to the source of the pain signal and what the brain does with that pain signal. I've had people with broken legs sitting and smiling because they felt no pain. Guided imagery can change the perception of the pain.
Yes. Guided imagery is very helpful for cancer patients, helping to relieve pain, fatigue, and anxiety, prepare people for surgeries and procedures, and helping them find meaning in their struggle if they are looking for that. See thehealingmind. Org and my book fighting cancer from within.
Yes. Guided imagery along with other techniques help one's emotional state and well being and with cancer treatment can definitely help patients get through the tougher times. Studies have shown that patients with a more positive outlook can do better in treatment for cancer.