Prevalence and associated factors of orphan symptoms in advanced cancer patients: a multicenter observational study

Purpose The aims of this study were to examine the prevalence of myoclonus, sweating, pruritus, hiccup, and vesical and rectal tenesmus, and to explore associated factors in patients with advanced cancer. Methods This multicenter prospective cohort study was conducted in 23 inpatient hospices/palliative care units in Japan from January to December 2017. The prevalence and characteristics of each symptom were assessed on admission and in the 3 days before death. We selected factors that might influence the occurrence of each symptom and investigated the association. Results A total of 1896 patients were enrolled. The prevalence of orphan symptoms rose from admission to the 3 days before death: myoclonus 1.3 to 5.3% (95% CI 0.9–1.9%/4.3–6.5%), sweating 1.8 to 4.1% (95% CI 1.3–2.6%/3.1–5.1%), hiccup 1.1 to 1.8% (95% CI 0.7–1.7%/1.2–2.6%), and tenesmus 0.7 to 0.9% (0.4–1.2%/0.5–1.5%). Prevalence of pruritus fell from 3.5 to 2.5% (95% CI 2.7–4.4%/1.8–3.4%). Sweating, pruritus, and hiccups persisted throughout the day in nearly half of the patients. Myoclonus was significantly associated with brain tumors, sweating with opioids and antipsychotics, pruritus with liver and biliary tract cancer, cholestasis and severe diabetes, hiccup with male gender, digestive tract obstruction, severe diabetes, and renal failure. Vesical tenesmus was associated with urinary cancer, antipsychotics, and anticholinergics and rectal tenesmus with pelvic cavity cancer. Conclusion We found that orphan symptoms occurred in 0.5–5.0% of patients, increased over time except for pruritus, and persisted in half of the patients.