Objectives: We evaluated changes in colorectal cancer (CRC) incidence and mortality by anatomic site to assess the possible impact of CRC screening.
Methods: Using data from 9 Surveillance, Epidemiology, and End Results cancer registries, we estimated trends in 1975-2007 CRC incidence and 1985-2007 incidence-based mortality. We evaluated trends separately for proximal and distal CRC, overall and by stage, tumor site, and race.
Results: Between 1975 and 2007, 323 237 adults in the study area were diagnosed with CRC. For most tumor and population subgroups, incidence rates increased between 1975 and 1985 and subsequently declined markedly. Declines were most rapid between 1999 and 2007 and were greater for distal than proximal CRC. Declines in incidence were greater for White than Black adults and greatest for regional-stage disease. There was little difference in trends across subsites within the proximal and distal colorectum. Declines in incidence-based mortality mirrored those for incidence.
Conclusions: Recent declines in CRC incidence and mortality are greater for distal than proximal CRC. Differing trends across populations may reflect variations in screening prevalence; distinct trends by tumor characteristics likely reflect differences in screening efficacy.