Background: In 2002 guidelines for the treatment of cancer pain (National Federation of French Cancer Centers) were adapted to the availability of drugs in France. In 2015, a group of experts nominated by the 3 French Societies involved in cancer pain (AFSOS, SFAP, SFETD: Supportive Care, Palliative Care and Pain Societies), reviewed these guidelines and established new ratios for morphine switching and/or changing the route of administration in patients whose pain was not adequately controlled. Methods: A review of the literature via Pubmed (key words: morphine, oxycodone, fentanyl, hydromorphone, methadone, tapentadol, pain, cancer, palliative care, opioid rotation, opioid switching, equianalgesic ratios) plus a manual search, led us to retain 43 original works containing good scientific evidence (methodology French Health Authority).Final approval for publishing was obtained from each of the aforementioned three scientific committees of the societies. Results: Experts explained why the theory of opioid rotation using fixed ratios was no longer appropriate for a secure practice. In the light of recent publications enhancing our knowledge on the efficacy of new drug switching ratios and for changing the route of administration of morphine, the group of experts recommended to use reconsidered switching ratios favoring security over efficacy, to minimize overdosing and adverse effects. Consequently, after the new conversion ratio (using slow release opioids) was applied, a second titration should be done by using normal release rescue formulations for breakthrough pain episodes. Conclusions: This work can be apply to an international situation (despite different drug availability amongst countries). A smartphone app is available for rapid and secure dose conversions and will be translated into English. The adequate opioid dose is obtained from a theoretical dose calculation adapted to patient’s personal situation and needs (second titration). Continuous updating of good practice guidelines may provide security and adequacy of prescription for adequate and safe pain relief for our patients, limiting overconsumption and risk of misuse.