The Myth of Blood Type: O Blood Type and Cancer Risk Despite claims that O blood type has the lowest cancer risk, research published in the journal "Scientific Reports" suggests otherwise. 

It found that individuals with O blood type have a 16.3% increased chance of contracting Helicobacter pylori infection, a bacteria associated with stomach cancer.

This interesting study challenges the belief that O blood type has superior immunity. If O blood type is indeed perfect, it should be able to combat even such a small bacterium. Looking at all four blood types, various studies have been conducted, but they lack consensus within the medical community.

These studies merely provide directions for future research. The blood type system has always been veiled in mystery, leaving much to be explored regarding its connection to immune response and diseases. The relationship between blood type and health still requires further exploration.