Cancer incidence and cancer mortality in relation to serum cholesterol.

We studied cancer incidence and mortality from cancer and coronary heart disease in relation to serum cholesterol levels in 92,710 individuals followed-up in the nationwide Swedish Cancer Register and the Swedish Cause of Death Register for 18-20 years. According to Cox's proportional hazard model, total cancer incidence and total cancer mortality were negatively correlated to serum cholesterol level (P less than .001). The negative correlations were most pronounced during the first years of follow-up. Cancer mortality data showed a stronger negative association to cholesterol than did incidence data during the first 10 years of follow-up (P less than .05). Mortality from coronary heart disease was positively correlated to serum cholesterol (P less than .001) during the entire follow-up. In contrast to most studies that were based on mortality data, our results of the comparison of incidence and mortality data of the same cohort are in agreement with those of a cholesterol-lowering effect of a preclinical cancer. Efforts by investigators and clinicians to lower serum cholesterol to prevent cardiovascular disease are, according to the present findings, not likely to increase cancer mortality risks but would extend life, irrespective of cause of death.

Serum levels of cholesterol and ischemic heart disease mortality. The Värmland Study.

The objective of the Värmland Study was to examine how serum cholesterol can be used to predict short- and long-term ischemic heart disease (IHD) mortality, especially in women aged 65 or older. This prospective cohort study involved about 20 years of follow-up after a single determination of serum cholesterol and included participants in a health screening undertaken from 1962 to 1965 (48,076 men, 48,732 women). The main outcome measures were mortality from IHD, acute myocardial infarction (MI), and chronic ischemic heart disease (CIHD). An IHD mortality trend was associated with increasing cholesterol levels for people younger than 65 years, and was more pronounced for men than women. For people 65 years or older, there was a weak trend for men, but not even a tendency for women. Regarding acute MI, significant trends were observed for males as well as females, for young as well as old people. A mild CIHD mortality trend was observed for young men. Otherwise no significant trend was seen.

Stability and validity of a single serum cholesterol measurement in a prospective cohort study.

The variation of serum cholesterol level was studied in a cohort of 16,281 individuals, with repeated measurements of cholesterol. The mean correlation coefficient between the two cholesterol values taken with a six-week interval on two occasions was 0.74. This correlation coefficient indicates a short-term variation of serum cholesterol, and reflects measurement errors and intra-individual fluctuations in cholesterol level, eg due to variations in dietary habits. The correlation coefficient for serum cholesterol values taken with a two-year interval was 0.66 and reflects a long-term variation. The ratio between these coefficients may be interpreted as a rough estimate of a correlation between the true cholesterol levels at a two-year interval, free from measurement errors and short-term intra-individual variations in dietary habits. The validity was assessed with the correlation between a single serum cholesterol value and mortality from myocardial infarction, in a cohort of 92,839 individuals followed-up for 14-16 years. The relative risks (RR) for death in myocardial infarction increased with increasing cholesterol levels. The RRs were in accordance with the well-established correlation between serum cholesterol and death from myocardial infarction. The results indicated a fairly high stability of the cholesterol level in blood and that the cholesterol values in the studied cohort were not less reliable than in comparable studies.

Screening for early detection of cancer--ethical aspects.

Ethical principles to be followed in cancer screening programmes are intended mainly to minimize unnecessary harm for the participating individuals. The principles that have been recommended by the Council of Europe, Committee of Ministers are: 1) Effectiveness is a necessary prerequisite for a screening activity to be ethical. 2) The need for a balance between the advantages and disadvantages of screening for a target population and an individual, between social and economic costs, equity and individual rights and freedoms. 3) The need for information about both the positive and the negative aspects of a screening programme. 4) The decision to participate in a screening programme or in research should be taken freely. 5) The right to integrity, i.e., the results of the tests are not communicated to those who do not wish to be informed, and the need to have laws and regulations on any communication of personal data derived from screening to third parties.

Relationship between Quetelet's index and cancer of breast and female genital tract in 47,000 women followed for 25 years.

The relationship between Quetelet's index and subsequent risk for cancer of endocrine target organs was studied in a cohort of 47,003 women, examined for height and weight in the years 1963-65, and followed up in the Swedish Cancer Register until 1987. High Quetelet's index was associated with a decreased risk for breast cancer among women less than 55 years of age at risk, while a high Quetelet's index predicted an increased risk among older women. Among women > or = 55 years of age, the excess relative risk for breast cancer associated with high Quetelet's index declined significantly during the follow-up period. Cancer of the ovaries and the uterine cervix were not significantly related to Quetelet's index in any age group. In women > or = 55 years of age, the relative risk for cancer of the uterine corpus associated to Quetelet's index was higher than that for breast cancer, and this association persisted during the entire follow-up period of more than 20 years. In spite of the fact that endometrial cancer is less common than breast cancer, because of the stronger relation between overweight and endometrial cancer, more endometrial cancer would be attributable to obesity than breast cancer.

Breast cancer risk in relation to serum cholesterol, serum beta-lipoprotein, height, weight, and blood pressure.

The relation between breast cancer risk and serum levels of cholesterol and beta-lipoprotein (BLP), height, weight, Quetelet's index and blood pressure was studied in a cohort of 46,570 Swedish women less than 75 years of age. The cohort was examined between 1963 and 1965 and followed up in the Swedish Cancer Registry until 1983. During this period 1,182 cases of breast cancer were reported. Of those, 196 were reported among women less than 50 years of age. Statistically significant positive associations were observed between height, weight, and systolic blood pressure and breast cancer risk. No clear trend in cancer risk related to serum cholesterol or BLP was seen in the total material. In a stepwise Cox multiple regression analysis only the associations with height and blood pressure remained significant. Among women, having their cancer diagnosed before the age of 50, higher Quetelet's index was associated with a lower cancer risk, whereas a positive correlation was seen among women greater than or equal to 50 years. In the group of younger women a high BLP level was associated with an increased risk of breast cancer. This relation became even stronger when studied in a multivariate analysis, which also showed a negative correlation between serum cholesterol and cancer risk.

Risk of stomach cancer in association with serum cholesterol and beta-lipoprotein.

The relation between serum levels of cholesterol and beta-lipoprotein (BLP) and stomach cancer risk was studied in a Swedish cohort of 92,710 individuals. The cohort was examined with a single measurement of cholesterol and BLP between 1963 and 1965 and followed up in the Swedish Cancer Registry until 1983. During the follow-up period 576 stomach cancers were reported. The risk of stomach cancer was negatively correlated to serum levels of cholesterol with a relative risk (RR) of 0.85 for every 40 mg/dl increase of cholesterol (p less than 0.001) and to BLP with an RR of 0.90 for every 3 units increase of BLP (p less than 0.01) when analysed one at a time. In a multiple regression analysis, however, only the relation to cholesterol remained statistically significant. The risk association seemed to be most pronounced between the third and fifth years of follow-up.

Risks of cancer of the colon and rectum in relation to serum cholesterol and beta-lipoprotein.

We studied the risk of colorectal cancer in relation to serum cholesterol and beta-lipoprotein in more than 92,000 Swedish subjects less than 75 years old. The cohort was examined between 1963 and 1965 and followed by means of the Swedish Cancer Register until 1979. During this period, 528 colon cancers and 311 rectal cancers developed. A positive association was observed between the serum cholesterol level and the risk of rectal cancer among men (P less than 0.05), with a relative risk of 1.65 in men with levels greater than or equal to 276 mg per deciliter (7.1 mmol per liter). An association was also observed between the serum beta-lipoprotein level and the risk of rectal cancer among men (P less than 0.05). When cholesterol and beta-lipoprotein levels were considered together, they were associated with both rectal and colon cancer in men. The relative risk in men with both cholesterol greater than or equal to 250 mg per deciliter (6.5 mmol per liter) and beta-lipoprotein greater than or equal to 12 units (2.2 g per liter) was 1.62 for colon cancer (95 percent confidence interval, 1.18 to 2.22) and 1.70 for rectal cancer (1.18 to 2.44). Similar trends were observed in women, although they were not statistically significant.

The general mammography screening program in Stockholm. Organisation and first-round results.

This presentation describes the organization and first-round results of the Stockholm mass mammography screening program, and discusses ways of checking the quality of an ongoing screening program. The Stockholm mammography screening program started in 1989 at five independent screening units, and comprises more than 150,000 women aged 50 to 69 years. The first round was completed in June 1991. Compliance during the studied period was 70.6%, and the recall rate was 3.0% of the attending women. Breast cancer was diagnosed in 676 women, of whom 90 (13.3%) had a cancer in situ. The cancer prevalence rate was thus 6.3 cancers per 1,000 screened women. Surgery was performed on 925 women, of whom 249 had benign lesions, giving a benign/malignant ratio of 0.37 to 1. Fifty-two per cent of the cancer patients were operated with breast conserving surgery. The median size of the invasive cancers was 12 mm; almost 80% were node-negative. Experience from the first two years of this mass mammography screening program shows that it meets the major quality requirements. One of the main future goals is to maintain the high quality of the program. Another important goal is a further increase in compliance.