Two separate systematic reviews and meta-analyses—both published recently in Neuromodulation: Technology at the Neural Interface—have concluded that intrathecal drug delivery (IDD) systems are effective in the management of cancer-related pain, with one report also finding an average reduction in opioid consumption of >50% after IDD.
Authored by Rui Duarte (University of Liverpool, Liverpool, UK) and colleagues, the first of these papers initially posits that IDD—a therapeutic option that involves the targeted delivery of analgesics to the intrathecal space—and spinal cord stimulation (SCS) systems have been proposed and assessed for the management of cancer pain, but “remain underused”.
As such, Duarte et al conducted a systematic review to evaluate the effectiveness and safety of IDD and SCS for cancer pain, searching a number of electronic databases for randomised controlled trials and observational studies of adults with pain related to cancer, or its treatment, who received an implantable IDD or SCS system from 1988 to 2021. Their primary outcome was the change in pain intensity from baseline to the last available follow-up measured using a visual analogue scale or numerical rating scale. A total of 3,043 participants who received either IDD or SCS for cancer pain across 22 studies were included.
Duarte and colleagues report that eight studies reporting data for 405 participants with an IDD system could be included in the meta-analysis of pain intensity that showed a statistically significant reduction at the latest post-treatment follow-up time versus baseline, while six studies reporting data for 325 participants with an IDD system could be included in the meta-analysis of pain intensity that showed a statistically significant reduction up to one month after treatment versus baseline. A meta-analysis including studies of participants with either an IDD system or an SCS device showed “similar results”, and improvements in other outcomes following IDD implantation were also observed, they add.
According to Duarte and colleagues, post-dural puncture headache was the most frequently reported complication, and urinary retention, nausea, and vomiting were all commonly reported side-effects.
“Our results suggest that IDD is an effective and safe management option, and provides pain relief for patients with cancer pain,” the authors conclude. “Statistically and clinically significant results were observed for reduction in pain intensity up to one month, and the latest post-treatment follow-up, compared with baseline. However, the results should be interpreted with caution because of the limitations of the evidence available.”
In the second recently published systematic review of IDD in cancer pain management—authored by Christophe Perruchoud (Hôpital de la Tour, Meyrin, Switzerland) and colleagues—researchers identified studies evaluating the efficacy and/or safety of IDD with external or implanted pumps in patients with cancer-related pain between 1990 and 2019.
They went on to perform a meta-analysis of the existing data, using mean changes from baseline in pain levels at short-, mid-, and long-term intervals to examine IDD’s efficacy. Secondary objectives of their study included the effects of IDD on systemic opioid use (changes in opioid [oral morphine equivalent] daily dose) and infection rates.
Perruchoud and colleagues state that, overall, pain levels were found to have decreased from baseline, noting that—on a 0–10 scale—mean differences were -4.34 at 4–5 weeks; -4.34 at 6–12 weeks; and -3.32 at >6 months. In addition, weighted mean oral morphine equivalent consumption was reduced by 308.24mg/d, while weighted mean infection rates were roughly 3% for external and implanted pumps. The authors describe the latter as being “comparable with other indications”.
As such, Perruchoud et al deliver a similar concluding message to Duarte et al, reporting that “meta-analyses show a statistically significant and sustained decrease in cancer pain with IDD, compared with baseline”.