A study of familial non-polypotic colorectal cancer.

The family history of colorectal cancer was examined in 601 patients with non-polypotic colorectal cancer. 33 (5.5 per cent) of these patients were found to have a family history. Colorectal cancer was found significantly more often in the families of those patients with the disease rather than in those with gastric cancer (5.5 per cent vs 3.0 per cent). The mean age was younger by five years in the patients with a family history than in those with no family history. The incidence of young patients, multiple cancers, and other cancers in relatives was significantly higher in the patients with a family history than in those without. No significant difference in cancer sites between the two groups was seen, however, there was a preponderance of right colon cancers in the young patients with a family history. There was one particular patient with seven affected relatives in his family. In this patient, an early age of onset, the presence of multiple cancers, including a right colon cancer, the occurrence of metachronous other cancers and the fact that one of his relatives was accidentally found to have an occult colon cancer were noteworthy. It is important to survey the family members of patients, especially the young ones, where there is a family history of colorectal cancer.