CNR1 and breast cancer: Other findings from clinical immunohistochemistry studies and rodent model experiments reported that higher CB1 and CB2 levels were linked to poor clinical outcomes in patients of renal cell carcinoma (Wang et al., 2018), head and neck squamous carcinoma (Klein et al., 2013), breast cancer (Blasco-Benito et al., 2019), and colorectal cancer (Martínez-Martínez et al., 2015).