Vitamin B12 deficiency occurs when the body does not absorb enough B12 from dietary sources or when dietary intake is insufficient. While it is primarily associated with conditions like pernicious anemia and gastrointestinal disorders, studies suggest that chronic B12 deficiency may sometimes be linked to certain cancers. https://sahyadrihospital.com/blog/can-vitamin-b12-deficiency-be-a-sign-of-cancer/