THC and a Standard Antiemetic Were Equally Effective Against Chemotherapy Nausea in 214 Patients | Research

The takeaway

In a large double-blind crossover trial, oral THC and prochlorperazine were equally effective at reducing chemotherapy-induced nausea and vomiting, though THC caused more side effects that patients did not mind.

Read this if you want to see how THC compared head-to-head with standard antiemetics in a large clinical trial.

214 patients in a double-blind crossover trial found equal efficacy

What the researchers found

Two hundred fourteen cancer patients were randomized in a double-blind crossover design to receive either THC (dosed by body surface area) or prochlorperazine (Compazine, a standard antiemetic) before chemotherapy.

Both drugs were equally effective at reducing nausea and vomiting across a wide range of chemotherapy regimens and tumor types. Neither drug was superior for appetite or food intake.

THC produced more side effects: reduced concentration (P < 0.01), less social interaction (P < 0.05), and reduced activity (P < 0.05). However, these side effects did not reduce patients' preference for the drug and were actually associated with better nausea reduction (P < 0.05).

An interesting pattern emerged: patients who correctly identified when they were receiving THC responded better to it than those who could not tell the difference (P < 0.05). Past marijuana experience and age did not affect how well either drug worked.

Why it matters

This was one of the largest and best-designed early trials of THC as an antiemetic. The finding of equivalence rather than superiority was clinically important: it meant THC was a legitimate alternative but not necessarily better than existing options. The "unblinding" effect, where patients who recognized THC responded better, raised important questions about expectation and placebo effects in cannabinoid research.

The numbers in context

214 patients evaluated. 75% had previously received prochlorperazine. THC doses: 7.5 mg (BSA < 1.4), 10 mg (BSA 1.4-1.8), 12.5 mg (BSA > 1.8). THC reduced concentration (P < 0.01), social interaction (P < 0.05), and activity (P < 0.05).

How the study worked

Double-blind, crossover design with 214 subjects. THC was dosed by body surface area (7.5, 10, or 12.5 mg). Prochlorperazine was 10 mg fixed dose. Both given orally one hour before chemotherapy then every four hours for four doses. Assessed nausea, vomiting, appetite, mood, activity, concentration, and social interaction.

What this study cannot tell us

Crossover design means each patient received both treatments, which may introduce carryover effects. The "unblinding" finding suggests the double-blind was not perfect, potentially biasing results. The study used oral THC with its variable absorption.

How to read the evidence

A large double-blind crossover RCT with 214 patients and multiple outcome measures. Strong design, though the unblinding issue introduces potential bias.

When this study was published

Published in 1982. Modern antiemetics (serotonin antagonists like ondansetron) have since become the standard of care for chemotherapy nausea.

The bigger picture

This trial contributed to the evidence base that led to dronabinol's FDA approval in 1985. Its finding that THC side effects were associated with better nausea control and were tolerated by patients helped shape the understanding that cannabinoid "side effects" and therapeutic effects may be linked.

Questions still open

Does the link between recognizing THC and responding better reflect an expectation effect or a pharmacological one? Would patients who cannot identify THC benefit more from a different antiemetic? Are the cognitive side effects of THC a necessary component of its antiemetic effect?

Common questions

Was THC better than the standard drug?

No. Both were equally effective at reducing nausea and vomiting. THC had more side effects but patients tolerated them.

Did past marijuana use help?

No. Prior marijuana experience was not related to how well THC worked as an antiemetic, nor was age.

Read the original research

Cannabis and cancer chemotherapy: a comparison of oral delta-9-THC and prochlorperazine.

Cancer, 50(4), 636-45

View on PubMed ↗

Citation

Ungerleider, J T; Andrysiak, T; Fairbanks, L; Goodnight, J; Sarna, G; Jamison, K. (1982). Cannabis and cancer chemotherapy: a comparison of oral delta-9-THC and prochlorperazine.. Cancer, 50(4), 636-45.