Primary squamous cell carcinoma of the rectum in Denmark.

Only a limited number of cases of primary squamous cell carcinoma (SCC) developed in the colon and rectum have been described in the world literature. This study represents the first population-based study of this rare cancer. Sixteen patients with primary SCC of the rectum diagnosed in the period 1978-1983 were identified from the Danish Cancer Registry. Eleven patients were excluded after revision of the histological specimens because the SCC in these cases were in connection with the squamous epithelium of the anal canal. SCC of the rectum in Denmark in the period 1978-1983 thus constituted 0.06% and 0.11% of the histologically verified rectal tumours in men and women, respectively. Case reports on these cases are given. One of the two males was homosexual and the other had never been married or lived with a woman. It is concluded that our findings support the hypothesis proposed by Austin that there may be an association between the frequency of anal intercourse and occurrence of squamous cell carcinoma of the rectum.