The theoretical risk of uncontrolled angiogenesis has been raised in mechanistic discussions and has not been adequately ruled out in humans (but dont take this as any sort of positive evidence that BPC-157 causes cancer0
Rahman, I., Mulier, B., Gilmour, P.S., Jeffery, P.K
This study showed that systemic administration of BPC-157 improved both the structural and functional properties of healing ligaments, with increased collagen content, improved fiber alignment, and greater ultimate tensile strength compared to untreated controls
The most common causes include B12 supplementation (particularly injections), liver disease releasing stored B12, haematological disorders increasing B12-binding proteins, and chronic kidney disease reducing B12 excretion
So it's actually a lab made peptide