The strategy to estimate the annual opioid need for cancer pain treatment is to assume that 60% of patients with advanced cancer will each use an average of 100 mg morphine per day for the last 100 days (three months) of their lives, i.e., a total of 10 g of morphine per patient.
Example: for a country with five million people and 3,500 new diagnosis of cancer per year — 2/3 of which present with stage III or IV cancer — if 60% of these patients (2,100) have pain and need 10 g of morphine each before they die, that country will need 21 kg of morphine per year just to manage cancer pain.
The opioid supply should include 30% immediate-release morphine, 60% slow-release morphine, 5% parenteral morphine, and 5% other opioids
Stjernsward J, Foley KM and Ferris FD. The public health strategy for palliative care. J Pain Symptom Manage. 2007. 33: 486-493.