What are the effects of large quantities of morphine on lung cancer patients?

Several: Dose dependent pain relief sedation respiratory depression of depth and rate and cardiac compromise can occur.

Depends: If the patient is having pain, then often large amounts of morphine are needed to relive that pain. Sedation is possible but unlikely if the patient is still having pain. Itching and nausea are common at first but wear off. Constipation is universal and does not wear off. At very high doses sometimes toxicities such as muscle twitching can occur and may be a reason to switch to another pain med.