The cancer pattern in Africans at Baragwanath Hospital, Johannesburg

Traditional and commercial alcohols and esophageal cancer risk in Kenya

Squamous cell esophageal cancer is common throughout East Africa, but its etiology is poorly understood. We investigated the contribution of alcohol consumption to esophageal cancer in Kenya, based on a hospital-based case-control study conducted from 08/2013 to 03/2018 in Eldoret, western Kenya. Cases had an endoscopy-confirmed esophageal tumor whose histology did not rule out squamous cell carcinoma. Age and gender frequency-matched controls were recruited from hospital visitors/patients without digestive diseases. Logistic regression was used to calculate odds ratios (ORs) and their 95% confidence intervals (CI) adjusting for tobacco (type, intensity) and 6 other potential confounders. A total of 422 cases (65% male, mean at diagnosis 60 (SD 14) years) and 414 controls were included. ORs for ever-drinking were stronger in ever-tobacco users (9.0, 95% CI: 3.4, 23.8, with few tobacco users who were never drinkers) than in never-tobacco users (2.6, 95% CI: 1.6, 4.1). Risk increased linearly with number of drinks: OR for >6 compared to >0 to ≤2 drinks/day were 5.2 (2.4, 11.4) in ever-tobacco users and 2.1 (0.7, 4.4) in never-tobacco users. Although most ethanol came from low ethanol alcohols (busaa or beer), for the same ethanol intake, if a greater proportion came from the moonshine chang'aa, it was associated with a specific additional risk. The population attributable fraction for >2 drinks per day was 48% overall and highest in male tobacco users. Alcohol consumption, particularly of busaa and chang'aa, contributes to half of the esophageal cancer burden in western Kenya.

Informing etiologic research priorities for squamous cell esophageal cancer in Africa: A review of setting-specific exposures to known and putative risk factors

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers in most Eastern and Southern African countries, but its etiology has been understudied to date. To inform its research agenda, we undertook a review to identify, of the ESCC risk factors which have been established or strongly suggested worldwide, those with a high prevalence or high exposure levels in any ESCC-affected African setting and the sources thereof. We found that for almost all ESCC risk factors known to date, including tobacco, alcohol, hot beverage consumption, nitrosamines and both inhaled and ingested PAHs, there is evidence of population groups with raised exposures, the sources of which vary greatly between cultures across the ESCC corridor. Research encompassing these risk factors is warranted and is likely to identify primary prevention strategies.

Cancer of the oesophagus in Africans in sub-Saharan Africa: any hopes for its control?

Oesophageal cancer, a highly lethal tumour, occurs to a variable extent in Africans in sub-Saharan African countries. In many, its incidence remains low, as in the Ivory Coast, Mali and the Gambia. However, in other African countries, the incidence rate has risen considerably, especially in city populations, as in Durban, South Africa, in Kyadondo, Uganda, and in Harare, Zimbabwe, rising to levels far higher than those reported in white populations. As to risk factors, in some African settings, smoking is a factor, and in others, alcohol consumption. Nutritionally, one enquiry, made in Durban, indicated the use of less-refined cereal products, with higher consumptions of vegetables and fruit, to be protective. In developed populations, protective factors are considered to be those characteristic of a "prudent" lifestyle. However, known risk factors largely fail to explain the high variability in the disease's occurrence. In seeking to combat the disease, it is thought unlikely that most Africans, especially urban dwellers, are willing to alter their lifestyle appropriately, even with the understanding that the changes would confer other protective benefits. This suggests that further rises, especially in the contexts of high incidence rates, are inevitable.

Toxicological evaluation of nitrosamines in condoms

Volatile N-nitrosamines have been found in rubber products including gloves, balloons, toys, baby bottle teats, soothers, and condoms. N-Nitrosamines are potent carcinogens, and therefore, European legislation has limited the release of N-nitrosamines and N-nitrosatable compounds in teats and soothers to 0.01-0.1 mg/kg rubber, respectively. Previously, endogenous nitrosamine formation in the vagina has been suggested as a cause of cervical cancer. It was speculated that exogenous N-nitrosamines and N-nitrosatable compounds from condoms may also lead to genital cancer. Therefore, we reviewed the literature and calculated the risk for the induction of tumors by nitrosamines from condoms. In vitro Biaudet et al. (1997) found up to 88 ng nitrosatable compounds migrating from condoms to cervical mucous within 24 hrs. During sexual intercourse about 0.6 ng may migrate in the female genital mucous membranes because of the short contact to the condom, e.g. 10 min. Comparable amounts of nitrosamines may also migrate in the penile skin. Estimating 1500 contacts to condoms during lifetime (50 condoms/year for 30 years) this may result in the adsorption of up to 0.9 microgram nitrosamines in total. Animal studies in Syrian hamsters showed the induction of local and/or systemic tumors, in particular liver tumors, after topical application of nitrosamines to the skin or mucous membrane at a total dose of about 1 g. This dose exceeds the dose to be expected from contact with condoms by more than 1 million. Also, epidemiological studies do not support a role for condoms in the induction of cancer. The incidence of cervical cancer and liver tumors is high in developing countries, where condoms are seldom used. In addition, humans are regularly exposed to nitrosamines from food and tobacco smoke at a dose which is 1,000 to 10,000 fold higher than expected from condom use. In summary, the risk for the induction of tumors from nitrosamines in condoms is very low.

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 children's 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.

Low survival of South African urban black women with cervical cancer

In Soweto, Johannesburg, the incidence of cervical cancer, the most common cancer in black women, is higher than in most white populations but lower than in many other populations. In a series of 210 patients who were diagnosed in 1981 and 1982, 50% had died within 1.6 years of diagnosis, a third of the reported survival time in white patients. The pattern of stage at presentation was similar to, although sometimes later than, those reported for various white communities. Data on patients' age at birth of first child, parity, smoking practice, and socioeconomic status, differed little from those in a control group. Neither these factors, nor availability of medical services, could be correlated with the distressingly short period of survival, which also occurs among urban black patients with breast and oesophageal cancers. Presumably, unidentified factors linked with low socioeconomic status affect survival time.

Bowel function in an urban black African population

Despite a low daily dietary fiber intake, an urbanized black African population in southern Africa has a low incidence of those diseases associated with fiber deficiency. Stool weights, defecation frequencies, and transit times in this group are much closer to those of westernized whites than to rural blacks.

Age of menopause in black women in South Africa

Among South African black women in rural areas, breast cancer is rare and remains very uncommon among urban dwellers in Soweto, Johannesburg. Since time of menopause is an influencing factor in breast cancer in white women, mean times were determined in series of 1850 and 1255 black women in rural and urban areas, respectively. Using probit analysis, respective means were 49.5 (SD 4.7) years, and 48.9 (SD 4.2) years. Values thus differ little from those reported for white women. Obviously case control studies are needed to learn of the bearing of menopausal age on breast cancer proneness in this very-low-risk population.

A suction-abrasive cytology tube for the diagnosis of esophageal carcinoma

A simple, easily constructed, and inexpensive suction-abrasive cytology tube was developed to study esophageal cytology. The reliability of this method for the diagnosis of esophageal carcinoma was evaluated in 101 patients. Of 47 patients with esophageal carcinoma, 93% were diagnosed correctly on exfoliative cytology. There were no false diagnoses of cancer. The cytology tube was well tolerated by all patients and provided a rapid and reliable method of diagnosis. As a screening procedure, this method may be applicable for widespread use to detect early esophageal cancer in high-risk populations.

Epidemiology of cancer of the penis

World-wide incidences of penile cancer are reviewed and epidemiologic factors including ciecumcision, hygiene, phimosis, smegma, irritation, infection, veneral disease, viruses, environment, race, immune response, trauma, and age are discussed. The lowest rates appear in groups practicing infant circumcision and in areas where standards of sexual hygiene are high.

Colonic cancer--hypotheses of causation, dietary prophylaxis, and future research

Colonic cancer is rare in primitive populations. In western populations it was uncommon in the past, but now accounts for about 3% of all deaths. The cause almost certainly lies with dietary changes. Probably, alterations in bowel milieu interieur, from interaction between metabolites and microbacteria, promote carcinogenesis. Changes in intakes of protein, fat, sugar, refined cereal products, and crude fiber have been advanced as predisposing or causative factors. Evidence suggests that (i) fall in fiber intake, but (ii) rise in fat intake, in their ability to increase fecal concentrations of bile acids and sterols (possible precursors of carcinogens) are most likely to be culpable. As preventive measures, a significant rise in fiber intake is practicable only from regular bran ingestion. A major reduction in fat intake is grossly unlikely. Even were rigorous dietary changes implemented, an early fall in colonic cancer incidence is highly improbable due to the long-term character of the disease. Future research must include characterization of the diet, metabolism, and disease pattern of segments of western populations who have low colonic cancer mortality rates; also, elucidation of the bearing of various intakes of different food components on the biochemistry and microbiology of the feces.

Carcinoma of the esophagus in Africans: establishment of a continuously growing cell line from a tumor specimen

Biopsy material, from a patient with an esophageal carcinoma of a type occurring relatively frequently in Africans in some regions of Southern Africa, has been adapted to cell culture conditions and has developed into a continuously growing tumor cell line. The cells have a squamous pattern of growth which they maintain, without piling up, even in heavily confluent cultures.

A retrospective study of the cancer patterns among hospital in-patients in Botswana 1960-72

Records of approximately 310,000 patients admitted to the 10 hospitals in Botswana between 1960 and 1972 have been studied and details of 1445 patients with malignant tumours abstracted. For the 894 tumours for which there was some supporting evidence--at best histological proof and minimally a clinical description of symptoms--proportional frequencies have been calculated for all sites and comparison made with the findings of other surveys. Cancer of the cervix uteri is overwhelmingly the most commonly occurring malignant tumour and the proportional frequency is among the highest observed in Africa south of the Sahara. Skin tumours are unusually common for Southern Africa in both sexes. In males, penile and prostatic tumours have a relatively high frequency whilst the frequencies for liver and lung are lower than in other parts of Southern Africa. Oesophageal cancer in males has a moderate frequency. Other tumours which show a marked variation of frequency within Africa--Kaposi's sarcoma and cancers of the stomach and bladder--are all low in frequency in Botswana. Tumours which are rare throughout Africa but common in Western Europe and North America--cancers of the colon, rectum and corpus uteri--are also rare in Botswana.

Smoking, drinking and oesophageal cancer in African males of Johannesburg, South Africa

A study of the smoking and drinking habits of 196 oesophageal cancer cases and 1064 control patients was made. All subjects were African males aged 35 years or more, drawn from a mainly urbanized population.It was found that tobacco smoking was prevalent and that pipe tobacco (used in pipes or in hand rolled cigarettes) was used more frequently than has been found in westernized countries. The drinking of alcohol was also a prevalent habit. Tribal affiliations were examined and all three of these factors showed differences between cases and controls. Further analysis of smoking and drinking together showed that only smoking had a positive association with oesophageal cancer, and this was also true after tribal adjustment had been made. A comparable analysis of data on Durban African males yielded similar findings.It was concluded that tobacco smoking was a powerful oesophageal insult but the authors were not able to show that alcohol was important in the development of oesophageal cancer in these people. Cigarette tobacco does not appear to be a significant oesophageal insult but pipe tobacco does, and the use of both these types of tobacco together may have a synergistic effect. Tribal affiliation has bearing on the smoking pattern.

The cancer pattern in African gold miners

The incidence of cancer among the African workers on the gold mines of South Africa has been studied for the period 1964-68. Considering the degree of selection to which they are subjected, the crude cancer rate was unexpectedly high.The most common cancers were those of the liver, the oesophagus, the respiratory system and the bladder. Geographical and tribal analysis showed that both liver and bladder cancers were predominantly found in Africans from Mozambique, while most of the oesophageal cancer occurred in Xhosas from the Transkei. The highest rate for cancer of the respiratory system was found in Africans from Natal, predominantly Zulu.The findings of this survey confirm those of previous South African surveys. The differences in cancer incidence are linked to both geographical area (physical environment), and to tribe, which may mean an association with tribal habit and custom. These factors need further investigation.