Background:The potential of an increased risk of breast cancer in women with diabetes has been the subject of a great deal of recent research.Methods:A meta-analysis was undertaken using a random effects model to investigate the association between diabetes and breast cancer risk.Results:Thirty-nine independent risk estimates were available from observational epidemiological studies. The summary relative risk (SRR) for breast cancer in women with diabetes was 1.27 (95% confidence interval (CI), 1.16–1.39) with no evidence of publication bias. Prospective studies showed a lower risk (SRR 1.23 (95% CI, 1.12–1.35)) than retrospective studies (SRR 1.36 (95% CI, 1.13–1.63)). Type 1 diabetes, or diabetes in pre-menopausal women, were not associated with risk of breast cancer (SRR 1.00 (95% CI, 0.74–1.35) and SRR 0.86 (95% CI, 0.66–1.12), respectively). Studies adjusting for body mass index (BMI) showed lower estimates (SRR 1.16 (95% CI, 1.08–1.24)) as compared with those studies that were not adjusted for BMI (SRR 1.33 (95% CI, 1.18–1.51)).Conclusion:The risk of breast cancer in women with type 2 diabetes is increased by 27%, a figure that decreased to 16% after adjustment for BMI. No increased risk was seen for women at pre-menopausal ages or with type 1 diabetes.

The purpose of this report is to present the descriptive epidemiology of colorectal cancer using the most recent data available to highlight two characteristics of the disease. First is the great variation which takes place in the frequency of this disease over geographic areas of all sizes. Colorectal cancer is common in most countries of North America and Europe, is rare in Asia and is particularly uncommon in Africa. Internationally, the variation in colon cancer is 60-fold, and within Europe there is a 4-fold difference in the incidence of colon cancer between areas with the highest and lowest rates. For cancer of the rectum, variation internationally is 18-fold and within Europe it is 3-fold. Within the United Kingdom, colon cancer is uniformly higher in the 5 Scottish Cancer Registry Regions than in their counterparts in England and Wales. Even within Scotland there is a 4-fold range of colon cancer incidence in rates, with the North and South clearly demarcated by a striking difference in colon cancer incidence in both sexes. Secondly, examination of international mortality rates for colorectal cancer demonstrates remarkable differences in trends over time between countries. In countries where colorectal cancer mortality rates were initially low, rates have increased substantially. In many countries where rates circa 1950 were moderately high, they have increased slightly or become stabilized. However, in countries such as Scotland, Canada, England and Wales and the United States, where rates were initially high, there have been gradual falls in mortality over time.

From 1972 to 2009, breast cancer mortality rates in Swedish women aged 40 years and older declined by 0.98% annually, from 68.4 to 42.8 per 100,000, and it continuously declined in 14 of the 21 Swedish counties. In three counties, breast cancer mortality declined sharply during or soon after the implementation of screening; in two counties, a steep decline started at least 5 years after screening was introduced; and in two counties, breast cancer mortality increased after screening started. In counties in which screening started in 1974-1978, mortality trends during the next 18 years were similar to those before screening started, and in counties in which screening started in 1986-1987, mortality increased by approximately 12% (P = .007) after the introduction of screening compared with previous trends. In counties in which screening started in 1987-1988 and in 1989-1990, mortality declined by approximately 5% (P = .001) and 8% (P < .001), respectively, after the introduction of screening. Conclusion County-specific mortality statistics in Sweden are consistent with studies that have reported limited or no impact of screening on mortality from breast cancer.

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The most recent data available demonstrate a 120-fold difference between the lowest and highest incidence rates of prostatic cancer, the disease being very common in North America, particularly among Blacks, and in Scandinavia, while it is rare in Japan and other oriental countries. The highest mortality for prostatic cancer is reported from St. Vincent and Grenadines, Martinique and Bermuda, from countries where the morbidity statistics are not available; the mortality rates reported from the United States and Canada are considerably lower. The incidence of and mortality from prostatic cancer have increased in most countries, in particular in areas with an initially low frequency of this disease. The ratio of mortality to incidence for prostatic cancer varies rather widely, being low in North America, Hawaii and Scandinavia. It is suggested that the observed variation in the mortality to incidence ratio for prostatic cancer could be due to differences in diagnostic practices between countries. This could explain, at least in part, the fact that the increasing trends of prostatic cancer incidence in North America are not accompanied by an increase in mortality from this tumour. This notion, however, does not exclude advances in treatment as possible determinants of the improved survival rate from prostatic cancer in this part of the world. The available statistics on prostatic cancer are based on the sum of clinically diagnosed carcinomas and those latent tumours found unexpectedly at prostatectomy and autopsy. The proportion of latent carcinomas among all prostatic cancer cases depends on the detection rate and varies from country to country, thus casting uncertainty on the comparability of prostatic cancer statistics from different areas. To avoid confusion in the statistics of prostatic cancer, it would be useful to consider introducing latent prostatic cancer as a separate entity in the next revision of the International Classification of Diseases (ICD).