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PubMed1977

[Determination of the importance of environmental factors in human cancer: the role of epidemiology].

The evidence in support of the assertion that 80% of human cancers are of environmental origin is reviewed. The environment is used in its broadest sense and is taken to include the widespread general exposures of air and water pollution, the work environment, exposures resulting from personal choice such as smoking and drinking, and the diet. Several examples are chosen to show that a wide range of environmental agents can cause cancer. Consideration of descriptive epidemiological data relating to migrants, geographical variation in incidence, changes in risk over time, correlation studies, clusters and case reports, supports an environmental etiology for many cancers the cause of which is at present unkown. The same data can be used to show that a large proportion of cancer is likely to be due to environmental factors. If the lowest rate observed in a series of populations be regarded as representing a residuum of cancers due to non-environmental causes then it is possible to imagine a hypothetical population with a very low rate indeed. However, it is unlikely that such a level could be achieved even if all causal mechanisms were understood as it is possible that factors leading to one cancer may protect against another. Until evidence to the contrary is aduced it is held that the vast majority of human cancers are due to the environment: the reasons why there has been reluctance to accept this conclusion are discussed.

Animals↗
PubMedDate not supplied

Rising trend of reported gonorrhoea and urethritis incidence in Burkina Faso from 1978 to 1983.

Rising trends in gonorrhoea and urethritis infection rates are being reported from most African countries. We investigated infection trends in Burkina Faso from 1978 to 1983, using data provided by the Ministry of Health. The data included monthly distribution of cases to permit analysis of seasonal variations, average number of reported cases per four-week period to estimate the yearly trend, actual number of reported cases per four-week period to measure the secular trend, and a single-period moving average as a more stable measure of disease occurrence. Seasonal trends demonstrate that the average number of reported cases of gonorrhoea is highest from January to May, declines from May to July, and levels off from August to December. The yearly trend from 1978 through 1983 increased by an average of 10.2% per year (P less than 0.001). The geographical distribution of the incidence in 1983 indicates that the northern region around Dori has the greatest number of reported cases. This high frequency is likely to reflect the severity of the problem among the nomads of the north since reporting would probably be low from this under-served and under-populated region. Peak incidence is correlated with the harvest season and may reflect increased sexual contacts among young, mobile men. The rising rate of gonorrhoea/urethritis infection is an especially urgent matter, given the expanding epidemic of human immunodeficiency virus in West Africa.

Burkina Faso↗
PubMed1991

Epidemic of caesarean sections in Brazil.

Brazil has one of the highest rates of caesarean section in the world. Patterns of caesarean sections were studied in a cohort of 5960 mothers followed from 1982 to 1986 in southern Brazil. Overall, 27.9% were delivered by caesarean section in 1982, this proportion being 30% for nulliparae, 80% for second deliveries when the first was by caesarean, and over 99% for third births when the first two were by caesarean. Socioeconomic status and requests for sterilisation by tubal ligation were important underlying factors. 9.4% of the women were sterilised during a caesarean section (3.7% in the lowest income group and 20.2% in the highest). 31% of women who had had their first child by a caesarean section and who were having a second operative delivery were sterilised. The high rates of caesarean sections and accompanying sterilisations reflect the lack of appropriate reproductive and contraceptive policies in the country.

Brazil↗
PubMed1988

Potential effect of revising the CDC surveillance case definition for AIDS.

The Centers for Disease Control (CDC) revised the surveillance case definition for acquired immunodeficiency syndrome (AIDS) in August, 1987. To determine the impact of this revision, information was extracted from the medical charts of the 630 patients receiving comprehensive medical care as of 1980 at 6 haemophilia treatment centres, and who were therefore likely to have been infected with human immunodeficiency virus (HIV). 38 (6%) and 47 (7%) met the 1985 and 1987 case definitions, respectively (22% increase). Of the cases added by use of the 1987 case definition, 3 patients had HIV dementia, 3 had Pneumocystis carinii pneumonia (2 of whom were presumptively diagnosed and 1 who had been receiving steroids and immunosuppressives), and 3 had HIV wasting syndrome. These data suggest that the revision of the AIDS case definition will have a substantial impact on future AIDS surveillance trends in persons with haemophilia and perhaps in other risk groups.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Residual paralytic poliomyelitis in a tropical region of Brazil, 1969-1977: prevalence surveys in different age groups as indicators of changing incidence.

The magnitude of the problem of paralytic poliomyelitis in recent years in the tropical Federal District of Brazil was estimated in 1980 by determining the prevalence of residual paralytic poliomyelitis in 10,007 schoolchildren born in 1969-1970 and in 10,794 schoolchildren born in 1973-1974. About 98% of these children attended school in the Federal District. The rate of residual paralytic poliomyelitis of 5.4 per 1000 children born in 1969-1970 was 2.3 times higher than the rate of 2.3 per 1000 born in 1973-1974, which may be related to increasing vaccination of children under one year of age. Paralysis appeared before four years of age in 96.5% of these children. These prevalence rates indicate a minimal average annual incidence of acute persisting paralytic poliomyelitis of 187 cases per million total population during the period 1969-1973 and of 80 per million total population during the period 1973-1977 compared with an average annual incidence of 135 reported persisting and non-persisting paralytic cases per million total population in the United States in the prevaccine era and of four persisting cases per 100 million during 1973-1978.

Age Factors↗
PubMed1990

Oral contraceptives and rheumatoid arthritis: new data from the Royal College of General Practitioners' oral contraception study.

From data available at April 1987 it was found that the standardised risk ratio for rheumatoid arthritis between current users of oral contraceptives and never users was 0.82 (95% confidence interval 0.59 to 1.15); the ratio between former users and never users was 0.94 (95% confidence interval 0.72 to 1.22). Important secular trends have occurred within our study population. The incidence of rheumatoid arthritis among former and never users has declined over the past two decades. Current users have not experienced this temporal trend, and the ratio between current and never users has, therefore, approached unity. These secular changes may explain why some studies have found that oral contraceptives have a protective effect, while others have been unable to show such an effect.

Adult↗
PubMed1978

Changes in the incidence of acute gonococcal and nongonococcal salpingitis. A five-year study from an urban area of central Sweden.

The incidence of acute gonococcal and nongonococcal salpingitis for a five-year-period (1970--74) was studied retrospectively in an urban area of central Sweden. The investigation was undertaken to see if the reported decrease of gonorrhoea in Sweden had been followed by a change in the incidence of gonococcal salpingitis--the most common complication of gonorrhoea. The study showed that the relative incidence of acute gonococcal salpingitis had decreased even more than urogenital gonorrhoea and these findings thus indicate a real decrease of gonorrhoea. At the same time there were more patients with nongonococcal salpingitis. During the period of the study the gonococcal complement-fixation test (GCFT) gave positive results in 40% to 80% of the patients with gonococcal salpingitis. The yield with this test was only 4% in patients with nongonococcal salpingitis during 1970 but it increased successively and was 23% in 1974. This increase was statistically highly significant (P less than 0.001).

Acute Disease↗
PubMed1989

Breastfeeding among low-income, high-risk women.

Data from a state supported project providing multidiscipline (clinical social work, nursing, nutrition, obstetrics, and pediatrics) assistance to low-income women judged to be at high perinatal risk by medical and social history were analyzed regarding infant feeding decisions. Data from 2,124 subjects delivered from 1976 to 1985 were available for analysis. The population tended to be single (77%), black (66%), poorly educated (63% less than a high school education), and young (mean age 21.8 years). Thirty-six percent were primiparas. The decision to breastfeed was associated with white race, older maternal age, higher educational level, marriage, and earlier utilization of prenatal care. Prenatal infant feeding plans were compared with actual postpartum decisions for 1,168 women. Only 3 percent of those initially planning to bottle feed changed their minds postpartum and breastfed although 31 percent of those initially planning to nurse ultimately chose artificial feeding. Ten percent of women were initially undecided; one-third of this group ultimately breastfed, two-thirds bottle fed. Overall the percentage of women in the project who were breastfeeding rose from 15 percent to 22 percent from the early to later years of the project (p less than 0.0001).

Adolescent↗
PubMed1992

Sex steroid hormones and breast cancer: is there a link with oral contraceptives and hormone replacement therapy?

OBJECTIVE: To determine whether use of sex steroid hormones for contraception and hormone replacement therapy alters the risk of breast cancer, and whether the risk varies with their composition, duration of use, the period of a woman's life when the hormones are used, and after successful treatment for breast cancer. DATA SOURCES: The results of important epidemiological reports, readily available from the English literature and published since 1981, were evaluated, using reports of basic scientific work as a background to the problem. STUDY SELECTION: An attempt was made to obtain most of the relevant reports. Twenty case-control and seven cohort studies were available on the oral contraceptive pill (OCP) and eleven case-control and five cohort studies on hormone replacement therapy (HRT). DATA EXTRACTION: The relative risk estimates for breast cancer (and their 95% confidence intervals) determined by each report were tabulated according to the specific conditions of analysis, for example users under age 25, duration of use. Results by meta-analysis from previous studies were also used to determine risk. A significant positive association was present when the risk estimate exceeded 1.0 and the 95% confidence interval did not cross 1.0. DATA SYNTHESIS: Among OCP users, the vast majority of reports showed no significant risk of breast cancer--overall, longest duration of use, and use before first full-term pregnancy. However, a positive association between breast cancer and users under age 25 was found in three of eight reports. Similarly, the majority of reports showed no significant risk of breast cancer among HRT users, overall as well as in relation to duration of use and interval since first use. There was no increased risk with additional progestogen; it may be protective. An improved prognosis was found in users who developed breast cancer. On the limited data, use of hormones for postmenopausal symptoms did not appear to be harmful to women who had been successfully treated for breast cancer. CONCLUSIONS: The review revealed good evidence that use of sex steroid hormones had no significant effect on the risk of breast cancer, whether given for contraception or hormone replacement. There was some concern about increased risk with prolonged use of the OCP, especially in younger women. At present, use of these hormones is a matter of informed choice, with individual considerations of the risk-benefit ratio.

Adult↗
PubMedDate not supplied

Family planning clinics: facing higher costs and sicker patients.

Family planning clinics throughout the United States are facing a variety of obstacles that threaten their ability to provide necessary contraceptive services to low-income women and teenagers, according to interviews with clinic administrators. In the last few years, the proportion of patients coming to family planning agencies in need of screening or treatment for sexually transmitted diseases (STDs) has increased dramatically. Many providers report that 10-15 percent of their clients are infected with chlamydia, the most prevalent STD. The increasing costs of Pap tests and contraceptives are also major problems: As a result of recent federal legislation, the price of Pap tests has risen substantially, and that of contraceptives is beginning to increase steeply. Finally, Title X funding for family planning services has decreased 66 percent over the last decade if both cuts and inflation are taken into account. As a result of the squeeze between increased costs and decreased public funding, clinics have been forced to charge higher fees, maintain long waiting lists for appointments and curtail community outreach. In addition, growth of the family planning patient population has slowed dramatically, and even declined, in some places.

Cost Control↗
PubMed1988

Risk factors for breast cancer in Chinese women in Shanghai.

Five hundred thirty-four histologically confirmed incident cases of breast cancer in Chinese women of Shanghai and an equal number of age and sex-matched population controls were interviewed as part of an epidemiological study of breast cancer risk factors. Early age at menarche was positively associated with breast cancer risk whereas early age at first full term pregnancy, high parity, and long duration of nursing were each negatively associated. We found high average body weight to be a risk factor, especially among women over age 60. Use of oral contraceptives after age 45 also was a risk factor, but use in general was not. Personal history of benign breast disease and history of breast cancer in first degree female relatives both increased risk. Multivariate analysis showed that each of these risk (or protective) factors was independently related to breast cancer. In addition to confirming most of the breast cancer risk factors of Western populations in a low risk developing Asian country, this study demonstrates a clear beneficial effect on breast cancer risk of lactation in a population characterized by a long cumulative duration of nursing in the majority of women. Finally, this study supports several other recent reports of a residual and beneficial effect of parity on breast cancer risk after controlling for age at first full term pregnancy.

Abortion, Spontaneous↗
PubMed1988

Recent decline in gonorrhea incidence in Israel: possible association with the AIDS pandemic.

The effect of the AIDS pandemic on the sexual behavior of the general population has not been clearly established. Since trends in the incidence of other sexually transmitted diseases may be a good marker of such behavioral changes, gonorrhea incidence in the civilian and military populations in Israel was examined during the period 1963-87. In the civilian population, the rates were relatively stable until 1967, when they increased to a peak in 1970 and then declined to the earlier levels. In 1982 a further decline began, which accelerated considerably in 1986 when the rates declined by 38%. During 1987 the decline was even more dramatic, with a drop of 60% compared with the rate of the previous year. A similar trend has been noted in the military population. The recent sharp decline in gonorrhea incidence may be related, at least partly, to a change in sexual behavior associated with the fear of AIDS. If so, its magnitude suggests that such changes have not been restricted to high-risk groups.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Cancers of the cervix uteri and breast: changes in incidence rates in Bombay over the last two decades.

The age-adjusted incidence rate of cervical cancer in Bombay has decreased over the last 20 years, whereas over the same period that of breast cancer increased slightly. Studies indicate that the incidence of cervical cancer is lower in successively later-born cohorts, but no cohort effect has been observed for breast cancer. Age at marriage is an important factor in the etiology of both these cancers, and it is plausible that the decrease in cervical cancer has resulted from the increase in age at marriage of women over the last 20 years in the city. The changing pattern of incidence of cancer for women in Bombay, among whom the incidence of breast cancer is the highest of all forms of cancer, indicates that, from a long-term perspective, cancer control programmes in India as a whole should aim at minimizing the risk of both cervical and breast cancer.

Adult↗
PubMed1987

Lactation and reproduction in Western Australian women.

There has been an increase in the incidence of breast-feeding in industrial areas, particularly in Western Australia, where one in four infants is breast-fed into the second year of life. Most of this increase in the incidence of breast-feeding is found in the higher socio-economic groups, pointing to a need to collect data on milk yield in such women. The levels of milk yield in women with infants between 1 and 6 months ranged from a mean of 1.13-1.24 kg/24 h. This is a higher level of milk production than the generally accepted range of 0.7-0.9 kg/24 h. However, this difference is due, in part, to a failure of previous test weighing methods to correct for the evaporative water losses in either the infant or mother. There was no relationship between the introduction of solids and a return to fertility in 38 women breast-feeding on demand. The return of the ovulatory menstrual cycle in women resulted in two acute changes in milk composition. These changes were characterized by a rise in the concentration of sodium and chloride and a fall in the concentration of potassium, glucose and lactose in breast milk. The first change occurred five to six days before ovulation, and the second occurred six to seven days after it. Following the cessation of breast-feeding, the concentration of lactose in breast milk gradually declined, but the concentrations of anti-bacterial proteins (IgA and lactoferrin) gradually increased to high levels over a period of 30-40 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Australia↗