Background: Breakthrough cancer pain (BTcP) has been shown to be a prevalent and poor prognostic factor for cancer patients, which remains undertreated and underdiagnosed. The Spanish Society for Medical Oncology (SEOM) developed a clinical practice guideline (CPG) for the treatment of cancer pain which specifically addressed the management of BTcP. Methods: With the objective of evaluate compliance with SEOM’ guideline, Fundación ECO designed a survey to identify awareness, perceptions, implementation and gaps, among Spanish medical oncologists. Results: A total of 83 oncologists with a median experience of 13 years responded. Although 87% of oncologists considered their clinical practice complied with SEOM recommendations, there were discrepancies between what oncologists agreed to do versus how they do in clinical practice, as shown in the table. Main barriers identified in our study were time pressure together with vague statements in some recommendations, and the need to regularly update to reflect the most recent knowledge on therapeutic management. Conclusions: Nonetheless, this nationwide survey reflects that oncologist’s clinical practice is increasingly guided by GPC, and thus, the evaluation process is necessary, both to gauge the true application of the GPC by the professionals and to evaluate their impact on health care.