Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies.

The development of radiotherapy in Slovenia.

The historical data on the development of radiotherapy in Slovenia are presented from its first use in this county in 1902 until the present. The Institute of Oncology in Ljubljana was established in 1938 with the intention of providing a sound development of radium and roentgen cancer treatment. After World War II, the development of radiotherapy was dynamic, which is evident from the data on new radiation sources in external beam therapy (accelerators, telecobalt units), in brachytherapy (various sealed radioisotopes) as well as in the introduction of therapy with unsealed radioisotopes.

Breast-cancer risk and oral contraceptive use in Slovenian women aged 25 to 54.

Results of a previous case-control study in Slovenia showed a significantly elevated risk of breast cancer for ever-OC users aged 25 to 54 years. A further study was conducted in 1988-1990 in the whole of Slovenia, employing more rigorous epidemiological methodology. Cases were 624 women with breast cancer, aged 25 to 54 years, diagnosed at the Institute of Oncology in Ljubljana and other Slovenian hospitals.

A case-control study of breast cancer in relation to oral contraceptive use in Slovenia.

With the aim to investigate a possible association between oral contraceptive (OC) use and breast cancer occurrence, 534 women aged 24--54 years with newly diagnosed breast cancer and 1989 individually matched hospital controls were interviewed during 1980--1983. The overall risk for ever-users vs. never-users estimated by logistic regression and adjusted for several possible confounding factors was 1.

Age at any birth and breast cancer risk.

In an effort to assess the relative importance of age at first birth, age at subsequent births, and total parity to the occurrence of breast cancer, reproductive data from 4,225 women with breast cancer and 12,307 hospitalized women without breast cancer were analyzed by a multiple logistic regression model. Age at first birth was confirmed to be the most important reproductive risk indicator; it was associated with a 3.5% increase of relative risk for every year of increase in age at first birth (the 95% confidence interval of this estimate was 2.

Age at menarche, urine estrogens and breast cancer risk.

In 511 nulliparous women aged 15-19 years and 347 aged 30-39, an analysis has been undertaken of the relationship of urine concentrations of the three principal estrogens to age, age at menarche and Quetelet's index of adiposity. The analysis was undertaken by means of multiple regression, controlling for each of the 12 centers from which the data originated, as well as for the other study variables. In the younger women, age was strongly and positively related to concentrations of E1 and E2 and less so to E3.

Age at menarche, probability of ovulation and breast cancer risk.

An analysis is undertaken of the frequency of ovulation in 17 groups of women aged 15 to 19 who had been the subjects of other studies. A urine specimen of at least 8 h accumulation had been provided on the 20th or 21st day of a menstrual cycle by 681 women. Analysis is restricted to 431 specimens which had been collected between 11 and 3 days prior to the onset of the subsequent menstrual period.

Computation of cancer incidence rates for defined small geographical areas--matching of numerator and denominator.

The authors present the problem of validity of numerator and pertinence of denominator for small geographical areas on sample of average annual crude incidence rates of stomach cancer in Slovenia during the period 1968--1974. At census in 1971 this country counted 1 727 137 of population. According to the residence of the patients the rates have been calculated for 60 municipalities, and besides for 29 so called "epidemiological regions", defined by their geographical and ethnic characteristics.

Maternal age and birth rank of women with breast cancer.

Data from a large international case-control study of breast cancer suggested that women born to young mothers had a 25% lower risk of breast cancer. The association was not secondary to a tendency for these women themselves to have had children at early ages. The data provided no indication of a meaningful association between breast cancer risk and birth rank.

Some international differences in treatment and survival in breast cancer.

In a recent study, 5-year survival rates for breast cancer patients in Boston (Massachusetts), Glamorgan (Wales), Slovenia (Yugoslavia) and Tokyo (Japan) were 57.3%, 49.5%, 41.

Age at first birth and breast cancer risk.

An international collaborative study of breast cancer and reproductive experience has been carried out in 7 areas of the world. In all areas studied, a striking relation between age at first birth and breast cancer risk was observed. It is estimated that women having their first child when aged under 18 years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of 35 years or more.

Lactation and cancer of the breast. A summary of an international study.

An international collaborative study has been carried out to test the hypothesis that prolonged lactation protects women against cancer of the breast. While pregnancy itself seemed to confer some protection against breast cancer in all areas studied, no consistent differences in duration of lactation were found between breast cancer patients and unaffected women, once the fact that breast cancer patients have fewer pregnancies had been allowed for. Even in areas where some women had lactated for a total of 5 years or more, such women occurred proportionately no less frequently among breast cancer patients than among unaffected women.