Opioids for pain treatment of cancer: a knowledge maturity mapping.

The conceptual structure of opioids, based on the bibliometric analysis of 4,935 articles of the Web of Science was constructed. The results were processed identifying the most cited articles to extract the main connections and frequencies of key words, authors, journals, countries, institutions, and their tendencies and their connection and degree of collaboration. The temporal tendencies, the word cloud, the keyword network, the evolution of words, author production and the scientific production by country are analyzed in terms of the increasing frequency in which opioids are employed to treat both cancerous and non-cancerous pain.