A.R.P. Walker

Case-control study of prostate cancer in black patients in Soweto, South Africa

nean countnes, such as Greece. In the same country. as in the UK (Cancer Statistics Group, 1982). rates vary regionally. Thev can also vary even between adjacent districts. as in Scotland (Kemp et al.. 1985). Incidence and mortality rates are rising in many countries (Davis et al.. 1990: Dofl, 1990). However, survival rates are improving (Bonnett et al.. 1988). In Third World populations. prostate cancer rates are very low among those living traditionally. However, rates rise in urban populations in transition, associated with changes in diet and other aspects of life-style (Parkin, 1986). In rural Africa, rates are very low (Gilpin et al.. 1989; Bah et al.. 1990): but are higher in those living in big cities (Cancer Registry of South Africa, 1988). According to this Registry.

Faecal pH, dietary fibre intake, and proneness to colon cancer in four South African populations.

In a series of South African populations, mean faecal pH values were found to be: rural and urban blacks, 6.12 and 6.15; Indians 6.21; coloureds (Eur-African-Malay), 6.29; these are significantly lower (p less than 0.01) than that of whites, 6.88. Apart from that of the coloureds, mean values for series of children and adults did not differ significantly. In the populations mentioned, corresponding mean dietary fibre intakes of childrens mothers (or associates of mothers) were all relatively low, namely, roughly 25 g, 18 g, 20 g, 21 g, 23 g, respectively. Frequency of colon cancer (also other non-infective bowel diseases, e.g. appendicitis) is very low in rural and urban blacks, is low in Indians and coloureds, yet much higher in whites. Thus, in these different ethnic populations, rarity or low frequency of colon cancer is associated more with low faecal pH than with level of dietary fibre intake, suggesting that components additional to fibre have a role in determining the milieu intérieur of the bowel and its proneness to disease.

Obesity in Black Women in Soweto, South Africa: Minimal Effects on Hypertension, Hyperlipidaemia and Hyperglycaemia:

STUDIES were made on 50 South African urban black obese women aged 25-40 years, with Body Mass Index (BMI) (Kg/m2) of 29.5 or more, and on 50 non-obese women with BMI of 25 or less. In the two groups, mean triceps skinfolds were 25.5mm and 17.8mm, respectively. Hypertension (≥160/95mm Hg) was present in 6 and 4 women (12% and 8%), hypercholesterolaemia (≥5.2mmol/l) in 5 and 3 women (10% and 6%), hypertriglyceridaemia (≥1.8mmol/l) in 5 and 3 (10% and 6%), and hyperglycaemia (≥7.8mmol/l) in 2 and 1 women (4% and 2%). One or more adverse sequelae were present in 11 (22%) obese and in 9 (18%) of non-obese women, proportions not significantly different. Dietarily, mean daily intakes were — Kcals 2273 and 2240, protein 73g and 70g (12.9% and 12.5% energy), fat 65g and 67g (25.7% and 26.9% energy), carbohydrate 349g and 330g (61.4% and 60.5% energy), and dietary fibre, 12g and 13g. In this low socioeconomic and low fat dietary context, obesity in the black women studied was not specifically evocative of deleterious sequelae of obesity.

Some puzzling situations in the onset, occurrence and future of coronary heart disease in developed and developing populations, particularly such in sub-Saharan Africa:

Coronary heart disease (CHD) was rare in developed populations until the early 1900s; this prevailed even among the small segments who were prosperous and who, in measure, had most of the currently recognised risk factors. However, in the 1930s, with improved circumstances from general rises in socio-economic state, there were major increases in the occurrence and mortality rate from the disease, the latter reaching a third of the total mortality in some countries, as in the United Kingdom (UK). Puzzlingly, the inter-population diversity of the increases in CHD has been such that there are as much as five fold differences in CHD mortality rates, as, for example, between Poland and Spain. Within recent years, with appropriate treatments, the mortality rate has halved in some countries, again, as in the UK. However, the incidence rate of the disease has diminished little or hardly at all. Risk factors include a familial component and, nutritionally, over-eating, a high fat intake, relatively low intakes of plant foods, especially of vegetables and fruit and, non-nutritionally, smoking, excessive alcohol consumption and a low level of everyday physical activity. On the one hand, known risk factors, broadly, are considered to be capable of explaining only about half of the variation in the occurrence of the disease. Even at present, known risk factors far from fully explain the epidemiological differences in mortality rates. Yet, on the other hand, there is abundant evidence that in population groups, among whom risk factors are low or have been reduced, CHD incidence and mortality rates are lower. Notwithstanding this knowledge, broadly, there is very little interest in the general public in taking avoiding measures. As to the situation in developing populations, in sub-Saharan Africa, in urban Africans, as in Johannesburg, South Africa, despite considerable westernisation of life style and with rises in risk factors, CHD remains of very low occurrence, the situation thereby resembling, historically, its relatively slow emergence in developed populations. In most eastern countries, mortality rates remain relatively low, as in Russia and Japan. However, in major contrast, in India, rates have risen considerably in urban dwellers. Indeed, in Indian immigrants, as in those in the UK, their rate actually exceeds that in the country’s white population. In brief, much remains to be explained in the epidemiology of the disease.

Low survival of South African urban black women with breast cancer.

In rural South Africa, in Eastern Transvaal (Robertson et al., 1971) and also Transkei (Rose & Fellingham, 1981), 20 years ago breast cancer incidence in black women was very low-about 2-3 per 100,000 (standardized to World population) (Doll et al., 1970). As a comparison, in Los Angeles (USA), also in the Bay area, the incidence rate for white women is 85 per 100,000 (World population) (Waterhouse et al., 1982). Current enquiries in Eastern Transvaal indicate that scarcely any increase has occurred. In urban centres, as in Soweto, Johannesburg, according to records at Baragwanath Hospital, breast cancer certainly occurred in the past more frequently than in rural areas, yet it was very uncommon (Isaacson et al., 1978). At present, enquiries reveal that after allowing for population increase, hardly any rise in frequency has taken place. In 1971-1972 and 19801982, incidence rates were estimated to be about 9 and 11 per 100,000, respectively (World population). Contextually, therefore, South African black women, especially rural dwellers, are at very low risk to breast cancer. As to orthodox risk factors (Chamberlain, 1982), their prevalences in these populations are low. Studies have shown that South African black women, compared with white women, are characterized by a somewhat later menarche, relatively early age at birth of first child, and high parity, with lactation being almost invariable and usually prolonged. Furthermore, habitual diet is low in animal foodstuffs; in particular it is very low in fat. It is high in fibre-containing foods in rural areas, although less so in urban areas (Manning et al., 1974; Groenewald et al., 1981). An important aspect of characterization, in the milieu of low risk to breast cancer, concerns survival time in the relatively small numbers of patients with the disease. Locally, no information is available; indeed, knowledge is almost nil on survival times of all cancers in Third World

Survival of Black Men with Prostatic Cancer in Soweto, Johannesburg, South Africa

While prostatic cancer has a low frequency in rural African black men living traditionally, the disease occurs more often and is increasing in black men in the cities. Between 1982 and 1984, 101 patients with prostatic cancer were detected in Soweto, Johannesburg. Of these patients 90 had clinical stage D disease and metastasis was common. The 50 per cent mortality period of 1.6 years, while similar to that reported in some series of white patients, is considerably shorter than that noted in several others series.

Third World policies and realities.

Dr. Grayson (February 21, p. 445) asks about changes in vital statistics of 3rd world populations as they develop. Of African populations, those in Johannesburg and other large South African cities, while still in transition, have now reached a relatively high level of sophistication. Their health pattern is likely to be that of other African countries as they prosper. The (IMR) infant mortality rate of blacks in Soweto, Johannesburg, is about 40/1000 live births, although nearer 30 in the regularly employed elite. This figure is similar to that for blacks in New York in 1965 and for class 5 persons in the United Kingdom. Small-town dwellers have higher IMRs and in rural areas the rates are higher still although they are decreasing everywhere. Family size is decreasing; in urban areas the average family has 3-4 children and the elite have 2-3. In Johannesburg during the 1960s, the birth rate was about 40/1000 and it is now 25. While the rate is higher in rural areas, it is falling. In the very young, gastroenteritis with or without malnutrition is still the leading cause of sickness and death in both urban and rural areas. Rates are however decreasing. Deficiency diseases, especially pellagra, remain a health problem in some areas. Tuberculosis still continues to be a major hazard although it is being dealt with. With the rise in socioeconomic status and associated changes in diet and lifestyle, obesity, especially in urban areas and especially among women, is becoming very prominent. Hypertension is more common and is the leading cause of natural death among urban dwellers. The toll from coronary heart disease and noninfective bowel disease remains inexplicably low, but diabetes is only somewhat less prevalent than it is among whites. Changes in cancar pattern and rates are slight; however, esophageal cancer in men and cervical cancer in women are the main causes of concern in the urban centers and some rural areas. Rising alcohol consumption is a major problem with its ramifications in pancreatic, liver, and heart problems. Cigarette smoking is now as common as among whites. Because of low rates for most degenerative diseases, blacks have, at middle age, a life expectancy exceeding that of whites. As sections of the 3rd world population prosper, the IMR decreases enormously as does family size. However, infections and malnutrition among the very young and tuberculosis in older groups remain important problems. Among adults, rises occur in some degenerative diseases but not in others, and diseases linked with hypertension and alcohol consumption have become formidably common, as they have in other developing and developed countries.

Can the Risk of Colon Cancer Be Lessened

Colon cancer was rare or uncommon in the past, and still is in traditionally-living third world populations. It now affects 3-5% of western populations. Epidemiological, case control, experimental and other studies suggest that proneness to colon cancer can be lessened by major dietary changes, principally decreasing fat intake by a third, and doubling the intake of fiber-containing foods, especially vegetables and fruit--recommendations similarly advocated for the avoidance of coronary heart disease and other degenerative diseases. Among nondietary factors, evidence indicates familiality, obesity and atmospheric pollution to be contributory, while parity, physical activity, solar radiation, high social class, estrogen use, and aspirin use, appear protective. Despite insufficiencies of knowledge of prevention, avoiding action should certainly be taken by those familially prone. For the rest, conceivably a prudent life-style could benefit a proportion avoiding colon cancer.