ABSTRACT
The results are presented of a case-control study conducted in the north of Iran. The main aim was to study factors identified in a previous study as potentially causally related to cancer of the oesophagus. Other tumours (lung, stomach, breast, large bowel, larynx and pharynx) were included to distinguish findings specific for oesophageal cancer from general characteristics of cancer patients, due for example to ascertainment bias, and to verify that expected associations, such as between lung cancer and cigarette smoking, would emerge under the prevailing field conditions. Two controls were chosen per case, matched for village of residence, age, sex and language group, Reinterviewing was performed to a limited extent to assess the accuracy of replies to questionnaires. The following were found not to be associated with oesophageal cancer: consumption of sheep's milk and yoghurt, sesame oil, chewing of nass, making of carpets, use of pregnancy diets, salting and sun-drying of meat and use of wild spinach. The use of opium, bread and tea could not be assessed in the retrospective framework. Strongly associated with risk of oesophageal cancer were low socio-economic status and low intake of fresh fruit and vegetables. The two factors each had an independent effect, and were more marked for oesophageal cancer than for the other tumours.
Subject(s)
Esophageal Neoplasms/epidemiology , Adult , Aged , Diet , Female , Housing , Humans , Iran , Male , Middle Aged , Plants, Toxic , Risk , Socioeconomic Factors , Tea , NicotianaABSTRACT
A linear logistic model used to estimate multiple risk functions in both cohort and case-control studies is adapted for sampling plans wherein each case is matched with R controls. The resulting methodology substantially liberalizes current practice by permitting simultaneous analysis of multiple discrete and continuous risk factors. Interactions among risk factors, and between risk factors and matching variables, may be explored. Data from two studies of oesophageal cancer, one conducted among Singapore Chinese and the other on the Caspian littoral of Iran, illustrate the methods.
