Table 2.

Relationship between expression levels of cannabinoid receptors, FAAH and MAGL and patient survival.

Tumour Type	Essential Result of the Studies	CB1	CB2	FAAH	MAGL	Reference
Breast cancer	No correlation of FAAH expression with disease-specific survival, but levels of FAAH significantly increased in patients with higher number of axillary lymph node metastases			↔		[45]
	Strong association between higher CB2 protein expression in HER2+ breast tumours and lower patient overall, relapse-free and metastasis-free survival		○			[47]
	High HER2–CB2 heteromer expression associated with lower disease-free and overall patient survival		○			[48]
Colorectal cancer	Higher CB1 expression correlated with poorer overall survival in stage IV; CB1 expression not correlated with patient survival following surgery in stage I/II or III cancer	○				[54]
	CB2 mRNA expression as prognostic factor for colon but not for rectal cancer; five-year overall survival for patients without CB2 expression was 76.16% versus 41.94% for patients with CB2 expression		○			[55]
	Higher levels of MAGL or lower levels of CB2 in tumour-associated macrophages of patients with colorectal cancer associated with better survival		○		○	[57]
Esophageal squamous cell carcinoma	Overexpression of CB1 in esophageal squamous cell carcinoma correlated with metastasis to lymph nodes and distant organs, and poor prognosis	○				[64]
Head and neck squamous cell carcinoma	Higher CB2 receptor expression associated with reduced disease-specific survival; CB1 receptor immunoreactivity not associated with survival	↔	○			[68]
Hepatocellular carcinoma	Disease-free survival in patients with hepatocellular carcinoma with high CB1 and CB2 expression significantly better than in patients with low expression	○	○			[69]
	MAGL low-expression group with significantly better survival than MAGL high-expression group				○	[71]
	Clinical prognosis for the MAGL high group markedly poorer than that for the MAGL low group in the 1-, 3-, and 5-year overall survival times and recurrence rates				○	[72]
Lung cancer	Lung adenocarcinoma patients with high CB2 level showed a shorter overall survival		○			[75]
	Patients with high expression levels of CB1, CB2 and CB1/CB2 showed increased survival	○	○			[76]
	Overall survival gradually reduced with increasing ABHD6 levels; no significant association with MAGL expression				↔	[77]
	High MAGL expression associated with worse outcomes				○	[78]
Mobile tongue squamous cell carcinoma	High CB1 and CB2 expression associated with longer overall and disease-free survival times	○	○			[83]
Pancreatic cancer	Correlation between longer survival and low CB1 receptor or high FAAH as well as MAGL levels; no correlation between survival and CB2 immunoreactivity	○	↔	○	○	[86]
Prostate cancer	High CB1 expression associated with a shorter survival time	○				[89]
	High tumour epithelial FAAH associated with a poor disease-specific survival			○		[91]
Renal cell carcinoma	Higher CB2 expression tending to have poor clinical outcomes in survival analyses		○			[95]

○, higher expression is associated with poorer survival (or vice versa: lower expression is associated with prolonged survival); ○, lower expression is associated with poorer survival (or vice versa: higher expression is linked with prolonged survival); ↔, no association of the indicated parameter with patients’ survival; CB₁, CB₂, cannabinoid receptor 1 or 2; FAAH, fatty acid amide hydrolase; HER2, human epidermal growth factor receptor 2; MAGL, monoacylglycerol lipase.