This paper reviews epidemiologic studies employing religion as an independent construct, and finds that most epidemiologists have an extremely limited appreciation of religion. After a historical overview of empirical religion and health research, some theoretical considerations are offered, followed by clarification of several operational and methodological issues. Next, well over 200 studies are reviewed from nine health-related areas: cardiovascular disease, hypertension and stroke, colitis and enteritis, general health status, general mortality, cancer of the uterine corpus and cervix, all other non-uterine cancers, morbidity and mortality in the clergy, and cancer in India. Finally, an agenda for further research is proposed.

Is there a religious factor in health

A retrospective study of cancer at high risk sites in the region of the head and neck was undertaken at the Bombay Cancer Registry, in 1968, to evaluate the effects of tobacco when chewed or smoked. There is sufficient evidence available today to indict chewing and smoking of tobacco as factors of great importance in the etiology of oral, pharyngeal, laryngeal, and esophageal cancers—the most common sites affected by the disease in Greater Bombay. This cause/ effect association is probably as intimate as that of cigarette smoking and lung cancer. The carcinogenic action of chewed tobacco is particularly evident at those sites where the bolus is retained in place for any length of time. Likewise, inhalation of tobacco fumes during the act of smoking produces a stream of gas and of solid particles which impinges directly on the oropharynx and especially on the soft palate initially and exposes smokers to the increased risk of developing cancer at exactly these posterior sites in the oropharynx, rather than more anteriorly in the oral cavity where the tissues do not directly bear the brunt of the onslaught from the smoke. It is revealing to find that the high risk sites involved in tobacco chewers appear to be the least affected in smokers, and vice versa.

Evaluation of cancer risk in tobacco chewers and smokers: an epidemiologic assessment

Some human milk contains particles physically identical to the mouse mammary tumour virus. Tumorigenesis in the mouse could serve as a model in the study of human breast cancer.

Search for a Human Breast Cancer Virus

Ribonucleic acid (RNA)-dependent deoxynucleic acid (DNA) polymerase activity in virus-like particles isolated from human milk was investigated. The survey included 13 human milks: all milks positive (4) for type B particles by electron microscopy contained particles that band at densities identical to those of the known oncogenic RNA viruses (1.16-1.19 gm/ml) and exhibited RNA-dependent DNA polymerase or "reverse transcriptase". The milks negative (9) for particles were also devoid of detectable reverse transcriptase. It is now possible to resolve by molecular hybridization the relationship between the human type B particles and the similar agents associated with mammary tumors in animals.

RNA-dependent DNA polymerase activity in virus-like particles isolated from human milk.

Incidence of cancer in India is lower than in the West and the commonly affected sites are very different. Cancers of the upper alimentary and respiratory tracts (oral cavity, pharynx, larynx, oesophagus, and lung) contribute more than half of the cancers in men and about a quarter in women. In this category, cancers of the oral cavity are very common in some parts of the country and cancers of the pharynx, larynx and lung in others. Indigenous habits of chewing and smoking seem to be primarily responsible for the high incidence of these cancers. Cancer of the cervix uteri is a major problem in women and cancer of the penis in men is relatively common in some parts of the country. Practical measures are discussed for the prevention of these cancers common in India.

Cancer epidemiology: the Indian scene.

The Bombay Cancer Registry has been in operation since June 1963 and reliable morbidity data on cancer have since been obtained for the first time in India, from a precisely outlined population base delineated by residential qualifications within strict geographicalboundaries. An attempt has been made to examine the differences noticed in the site-specific cancer risks, between 2 groups of people living in this area—the Parsi community and the total Bombay population. The over-all age adjusted rates for the Parsis were found to be lower than those for the total population and more noticeably, their site-specific risks seem to differ radically from the Greater Bombay pattern. Thus, cancers of the buccal cavity, pharynx, larynx, oesophagus and cervix uteri, which are frequently seen in the total Bombay population, are less commonly observed in the Parsi community. On the other hand the Parsi rates are higher at sites such as the female breast, body of uterus, ovary, prostate and skin and for all leukaemias. Even though the population pyramid of the Parsi community is very different from that of the total population of Bombay, age correction does not change the basic outline of risk patterns noted in the 2 groups. Such site-specific contrasts are believed to be due to differences present in the habits, customs and economic status of the two groups. (A study of the probable aetiological factors of epidemiological importance involved in this segment of the population, is already under way in Bombay, in an effort to identify the reasons for the differences noted in cancer risks at different sites.)

Differences observed in the site incidence of cancer, between the Parsi community and the total population of greater Bombay: a critical appraisal.

THE Bombay Cancer Registryt has been in operation since June 1963 and reliable morbidity data on cancer are being obtained for the first time in India, from a precisely outlined population group resident within strict geographical limits. Techniques of proved value, used by well-established registers, have been adopted. In this report, the results ofthe first 2 years ofthe survey (1964-65) are presented and an assessment is made of the value of the diagnostic criteria used. Evaluation of the rate at which cancer incidence increases with age gives additional useful data for establishing the degree of cancer risk in a given population, when considered together with evaluation of the incidence rate.

M V Natekar

Papers

Differences observed in the site incidence of cancer, between the Parsi community and the total population of greater Bombay: a critical appraisal.

Cancer incidence in greater Bombay: assessment of the cancer risk by age.