Cancer-Pain Cannabis Spray Extensions Cannot Replace a Controlled Comparison
Improvement during an open-label cannabis-spray extension is different from evidence that the spray caused that improvement. A study of patients with advanced cancer reported sustained symptom improvements among continuing participants, but its follow-up phase had no blinded placebo comparison.
Who entered the extension
Forty-three patients who had participated in a previous randomized trial entered the follow-up. Thirty-nine received THC/CBD oromucosal spray and four received THC spray. They had cancer-related pain inadequately controlled despite opioid treatment and adjusted spray use toward relief or their maximum dose.
What the follow-up reported
The THC/CBD group reported improvements from baseline in pain measures and several quality-of-life domains. The abstract reported no new safety concerns and no evidence of dose escalation among patients who continued treatment. These are observations in a selected continuing group, not proof of identical long-term outcomes in everyone who started the parent trial.
Continuation changes the question
An extension can describe what happened to people who remained on treatment. It cannot recreate the original randomized comparison when participation, continuation and dosing depend on clinical circumstances. Symptoms, other care and the composition of the observed group can change over time.
The unequal treatment-group sizes also limit comparisons between THC/CBD and THC alone. This report does not supply a reliable head-to-head estimate from four THC-only participants. Nor does absence of observed dose escalation establish that tolerance never occurs. For an individual treatment history, record the formulation, changing symptoms, other medications and reasons for continuation or discontinuation.
Related: interpreting cannabis tolerance claims.
Research cited
Johnson JR; Lossignol D; Burnell-Nugent M; Fallon MT. An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesics. Journal of pain and symptom management (2013). doi:10.1016/j.jpainsymman.2012.07.014. Findings discussed from the study abstract.
