vention.8 As described previously,8 aspirin use
was defined as regular use of aspirin during
most weeks, whereas nonuse of aspirin was defined
as no regular use of aspirin during most
weeks.
Analyses of PIK3CA, BRAF, KRAS, Microsatellite
Instability, and DNA Methylation
DNA was extracted from paraffin-embedded tissues.
15 Polymerase chain reaction and pyrosequencing
of PIK3CA (exons 9 and 20),15,24 KRAS
(codons 12 and 13),25 and BRAF (codon 600)26
were performed as previously described. Microsatellite
instability status was determined as previously
described.27 Methylation analyses of long