Palliative sedation for cancer patients in a tertiary palliative care unit in Argentina.

VEGA, F; DRAN, GRACIELA; MAMMANA, G; CULLEN, C; BIONDI, C; PASTRANA. T; RUGGIERO, RAÚL A.; CAMERANO, GABRIELA V.; ARMESTO, ARNALDO; BERTOLINO, MARIELA

Viena

Congreso; 18th ECCO-40th ESMO European Cancer Congress; 2015

Pain is one of the most frequent and distressing cancer related symptoms affecting from 70 to 90% of the palliative care patients with advanced cancer. Despite considerable advances in strong opioid therapies, high rates of under- treatment persist. In developing countries, a paucity of reports documenting strong opioid indications and lack of consensus- based guidelines are additional obstacles. The present study aimed to illustrate some features of the prescription of strong opioids as the first line treatment for pain in cancer patients during the first month of treatment at a Tertiary Palliative Care Unit. Of note, only 70% of the whole population in this study had advanced cancer, in contrast with previous reports indicating that patients usually access to PC in advanced stages of their malignant disease. While current literature points out morphine as the mainstay in patients with pain requiring Step III opioids 6,7, our data indicated that Methadone was the most frequent strong opioid, both as the initial and final choice. In this sense, the rotation to methadone from other opioids has been vastly documented but little is reported regarding the use of Methadone as a first line choice. In a review made in 2002, Bruera et al. concluded that Methadone may be an important alternative first-line agent for CR- pain, underlying the need for further research in this area. Afterwards, other studies showed its safety and comparable analgesic efficiency and tolerability than morphine[i],[ii],[iii], in some cases devoid of opioid-induced hyperalgesia[iv]. Nevertheless, Methadone use is infrequent in developing countries13, probably due to its specific pharmacokinetics, variable conversion ratio and long and unpredictable half-life, requiring careful dose titration and profound clinical skills for its administration[v],[vi]. Many reasons may account for the high rates of use of Methadone evidenced herein; a wide experience of the PCU professionals, the versatility of routes of administration (oral, rectal or sublingual), the close follow up of our patients and the lack and high cost of other long acting opioids in our community.In those patients followed up for a longer period, a significant rise in opioid doses expressed between the first and last assessments was found, which occurred mainly in the first 15 days probably due to the time needed for dose stabilization. It is worth pointing out that such increase, although statistically significant, may not be clinically meaningful. In fact, the overall mean opioid dose along the whole study period did not increase significantly and kept relatively low (< 50 mg Morph) compared with the doses reported by other studies[vii]. It is plausible that the multidimensional management of pain, characteristic of the palliative care, accounts for this fact. Pain intensity in the last consult was significantly lower than values recorded at admission. Analysis indicated a marked decrease in self-reported moderate and severe pain, with 31% of the patients reporting no pain at the end of the study time, suggesting that a good control of pain was achieved. Opioid rotation was performed in 23% of the cases. Notably, the switches were more than twice less frequent when initiating on Methadone than on other opioid, and the mean interval between the primary opioid and rotation was twofold, suggesting Methadone provides better control of the symptoms. The main cause for rotation was opioid- induced neurotoxicity, unlike other works reporting pain as the main cause for OR15. Other frequent symptoms requiring OR might have been controlled by prophylactic antiemetic and laxative, which are routinely prescribed to all patients who start opioid treatment at the PCU. Although conclusion here is strongly limited by the high proportion of sub- registration, our preliminary results are indicative of the preference of first line Methadone in the management of CR- pain, accounting for more than two-thirds of the indications at the PCU. In addition, Methadone seemed to provide good pain relief with low necessity of rotating to another opioid. The trends observed in this pilot study will guide the design of a hypothesis-driven prospective study pointing to ascertain Methadone efficacy and benefits and clarify reasons for its eligibility, providing useful information for low recourses countries with scarce alternatives for opioid medication10.Major limitations of this study are a deficient assessment of baseline data, the lack of information regarding opioid- and opioid rotation- induced side effects, the undocumented coexistence of onco-specific or other treatments, its retrospective design, the small population sample, and incomplete documentation, including missing charts.