疫学からみた大腸癌をめぐる2，3の問題

An Epidemiological Approach to Cancer of the Colon and Rectum

　従来，ことにわが国では感染症などを除くと疾病に対する疫学面でのアプローチが比較的等閑視されてきた．しかし，疾病を予防するには疾病の原因を明らかにすることが第一歩であり，そのためにはcase studyの集積を中心にした経験に立脚する臨床医学だけでなく，populationを巨視的に捉えていく疫学的手法の導入も重要なことである．このような立場から，私たちはこれまでに消化性潰¹⁾，胃癌²⁾などの胃疾患³⁾，あるいは小腸疾患⁴⁾に対する疫学的アプローチを試みてきた．

　悪性腫瘍の発生論に関してはいまだ明らかでなく，大腸癌もその例外ではないが，動物実験や糞便の生化学的，細菌学的分析などから一部では腸内細菌叢や胆汁酸の意義などが論じられている⁵⁾⁶⁾．

　Although cancer of the lower digestive tract is relatively infrequent in Japan, its mortality rate has increased since the end of the World War Ⅱ. The morbidity and mortality rates from colorectal cancer are presumed to increase still more in future, and the evaluation for this disease is demanded not only from clinical medicine but also from the standpoint of people's health preservation or preventive medicine.

　In this paper, it has been tried to compare the mortality rate between Japan and other countries, and to investigate year trend, regional difference and specificity of age and sex of colorectal cancer in Japan. Finally, the genetic disposition such as the frequency of familial occurrence and blood groups, and the environmental factors to colorectal cancer were discussed.

　From this study, it could be concluded that it is very important to grasp the health conditions of much larger population in order to approach the cause of a disease, although it is also meaningful to be investigated from patient's side as before. The understanding of etiology of colorectal cancer would thus become much deeper.