Changes in the localization of colorectal cancer: implications for clinical practice.

A hospital-based study was performed in order to examine the subsite distribution of colorectal cancer diagnosed in 1992-93 in the Zaanstreek region. The localization was compared with tumours diagnosed in the years 1972-73 and 1982-83. The number of colorectal cancers has markedly increased, and a significant rise in localization of tumours proximal to the splenic flexure has occurred (32% in 1972-73 to 43% in 1992-93). There also appears to be greater incidence of colorectal cancer in women. A trend towards an increase of proximal localization of tumours in women was noted. Possible explanations for this phenomenon are discussed. The results of this study suggest the importance of improved diagnostic accuracy in colorectal cancer and, in addition, may have consequences for screening programmes.