Background: A cancer diagnosis and associated treatment pathways are very stressful events, leading to approximately one-third of cancer patients dealing with psychological problems. Patient Reported Outcome Measures (PROMs) have potential to enhance the identification of cancer patients' psychological and physical needs and facilitate an appropriate care response. As end-users, health professionals are key to the successful adoption of PROMs, but there has been limited focus on their perspectives. Aggregating evidence from qualitative studies about the attitudes of healthcare professionals towards PROMs in oncology can help to address this deficit. This chapter presents findings from a systematic review and mixed-method synthesis to report on the challenges that health professionals encounter when dealing with patients' psychological distress. Methods: Guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, Medline, Cinahl, Embase and PsychInfo databases were searched for records published between 1998 and 2018. Qualitative and mixed-method studies were included where primary findings about the attitudes of health professionals towards PROMs in oncology were reported in English. The Critical Appraisal Skills Programme (CASP) Qualitative Research Checklist was applied to appraise study quality. Extracted data were analysed via a sentiment analysis and a meta-synthesis was conducted. Results: Following the removal of duplicates, 1227 articles were screened, with 34 articles meeting inclusion criteria. Appraisal using the CASP checklist determined studies to be, on average, of good quality. Metasynthesis highlighted the challenges professionals experience in: identifying patient issues and needs via PROMs; managing and addressing patient issues; the care experience; and the integration of PROMs into clinical practice. However, results from a sentiment analysis on primary text demonstrated an overall positive polarity from the expressed opinions of health professionals. Conclusion: How PROMs fit with existing practice, how they are valued, and the capacity to respond to PROMs are vital factors for the adoption of PROMs, from the perspectives of health professionals. Further research is needed, especially concerning the perspectives of patients, to guide implementation efforts.