LAUSR

### Highlights There is no clear definition of orphan symptoms. There is a group of symptoms that are seldom evaluated in most symptom assessment tools which can be considered as orphan symptoms.1 These are generally prevalent symptoms that are unaddressed in clinical practice, yet often not reported by the patients or by healthcare professionals.2 Orphan symptoms may be defined as symptoms not regularly assessed in clinical practice, and consequently little studied and not properly treated. No epidemiological or clinical studies generally exist to gauge the prevalence of the symptoms chosen; nevertheless, these symptoms are distressing for patients and their families. Orphan symptoms remain unaddressed in clinical practice if not highlighted by the patient or specifically sought by the healthcare professional. These symptoms may have a significant impact on the remaining quality of life (QoL). In these guidelines, only selected orphan symptoms are discussed. Among the most frequent orphan symptoms in patients with cancer that are related to the tumour or the antitumour treatment are muscle cramps, myoclonus, taste alterations, xerostomia, cough, hiccup, rectal tenesmus and restless legs syndrome (RLS). No epidemiological or clinical study exists regarding the prevalence of most orphan symptoms in patients with cancer. These symptoms are really distressing for patients and their families. Several case series and case reports, but very few prospective trials, have been published until now. For this reason, the levels of evidence (LoEs) and grades of recommendation (GoRs) are generally low. These European Society for Medical Oncology (ESMO) Clinical Practice Guidelines on management of orphan symptoms are the first …