It is well established that the risk of colorectal cancer (CRC) is increased if a first degree relative (parent, brother, sister) has had CRC. What is the risk if CRC was found in a second degree relative (grandparent, aunt, uncle)? A huge study in Sweden looked at 16 million individuals over more than 50 years. There was only a minor, insignificant increased risk if a second degree relative was affected. Interestingly, the risk if a half-sibling had CRC was the same as if a full sibling did. British Medical Journal March 2019. MS
