Relationship between Cannabis Use and Opioid Use in Patients with Cancer Metastatic to Bone in a Large Multicenter Cohort from a State with Legalized Adult Non-Medical Cannabis

Purpose/Objective(s)

Patients with cancer who use cannabis frequently note pain as a reason for their cannabis use. Available data do support cannabis use for management of pain in some settings, though the effectiveness of cannabis for cancer-associated pain is less clear. Based on limited data, some have suggested that cannabis might be used as an alternative to opiates for management of cancer-related pain. We sought to determine the relationship between cannabis use and opioid use in a multicenter cohort of patients undergoing radiotherapy for bone metastases.

Materials/Methods

On January 1, 2021, questions about cannabis use were added to Michigan Radiation Oncology Quality Consortium (MROQC) questionnaires for bone metastasis patients. Pain scores, opioid use, social, demographic, and disease characteristics were also prospectively collected. A multivariable model using logistic regression identified associations between recent cannabis use and opioid use, accounting for relevant patient and disease characteristics.

Results

Since questions on cannabis were introduced, 2,096 patients have been enrolled. A total of 1143 of 2096 (54.5%) completed questionnaires about recent cannabis use; 1912 of 2096 (91%) completed questionnaires about current opioid use; and 1064 of 2096 (51%) completed both. Among those who completed both, 132 of 1064 (12%) reported recent opioid and cannabis use, 320 of 1064 (30%) reported recent opioid but not cannabis use, 57 of 1064 (5%) reported no recent opioid but recent cannabis use, 281 of 1064 (26%) reported no recent opioid or cannabis use, and the remaining individuals (274/1064 [26%]) declined to answer cannabis use questions by selecting “decline to answer”. In a multivariable model, cannabis use [OR = 2.11 (95% CI = 1.37, 3.26) P = 0.001], along with pain score [Score 1-3 vs 0, OR = 2.32 (95% CI = 1.36, 3.94); Score 4-7 vs 0, OR = 6.55 (95% CI = 4.06, 10.6); Score 8-10 vs 0, OR = 11.20 (95% CI = 6.32, 19.8), P < 0.001], NSAID use [OR = 1.66 (95% CI = 1.17, 2.37) P = 0.005], prior systemic therapy [OR = 0.54 (95% CI = 0.37, 0.78) P = 0.005], and number of metastatic lesions [3-5 vs 1-2, OR = 1.57 (95% CI = 0.95, 2.26); 5-10 vs 1-2, OR = 1.54 (95% CI = 0.91, 2.59); 11+ vs 1-2, OR = 3.26 (95% CI = 2.06, 5.15) P < 0.001] predicted opiate use while age, gender, and race did not.

Conclusion

Patients with bone metastases frequently use cannabis, opioids, or both. Though it has been suggested that cannabis availability might reduce opioid use among patients with cancer, our finding that cannabis use predicts opioid use does not support this hypothesis. These data suggest a more complex relationship between cannabis use and opioid use in this population. Further study is needed to assess risks of concurrent cannabis and opioid use and to explore patient rationale for concurrent usage.