Expert conference on cancer pain assessment and classification--the need for international consensus: working proposals on international standards.

An increasing number of cancer patients live longer, and palliative care has become an important part of their treatment. Symptoms are often inadequately assessed and managed. A significant challenge in clinical trials is to control for the variability of the samples being studied. To overcome this problem, classification systems have been developed in order to characterise and stratify patients by grouping them according to major common characteristics. The lack of agreed methods for the assessment and classification of cancer pain has been clearly indicated in clinical trials and in clinical practice and may be one possible explanation for the inadequate treatment of cancer pain. This was the background to an international expert meeting arranged in September 2009 in Milan, Italy. The primary aims were to produce recommendations on how to assess and classify cancer pain and to recommend a strategy for the further development, validation and implementation of an international cancer pain classification and assessment system. The recommendations consisted of two basic working proposals, nine specific working proposals and seven recommendations for the further development of a cancer pain classification system. Examples of specific working proposals were to include pain intensity, pain mechanism, breakthrough pain and psychological distress as the core domains in this classification of cancer pain and to measure pain intensity with a 0-10 numerical rating scale with 'no pain' and 'pain as bad as you can imagine' as anchors. The proposed name for this international standard is Cancer Pain Assessment and Classification System (CPACS).