Thriving for Clues in Variations Seen in Mortality and Incidence of Cancer: Geographic Patterns, Temporal Trends, and Human Population Diversities in Cancer Incidence and Mortality

Worldwide, breast cancer is the most common cancer and is the leading cause of cancer death among women. To describe global trends, we compared age-adjusted incidence and mortality rates over three decades (from 1973-77 to 1993-97) and across several continents. Both breast cancer incidence and mortality rates varied 4-fold by geographic location between countries with the highest and lowest rates. Recent (1993-1997) incidence rates ranged from 27/100,000 in Asian countries to 97/100,000 among US white women. Overall, North American and northern European countries had the highest incidence rates of breast cancer; intermediate levels were reported in Western Europe, Oceania, Scandinavia, and Israel; and Eastern Europe, South and Latin America, and Asia had the lowest levels. Breast cancer incidence rose 30-40% from the 1970s to the 1990s in most countries, with the most marked increases among women aged > or =50 years. Mortality from breast cancer paralleled incidence: it was highest in the countries with the highest incidence rates (between 17/100,000 and 27/100,000), lowest in Latin America and Asia (7-14/100,000), and rose most rapidly in countries with the lowest rates. Breast cancer incidence and mortality rates remain highest in developed countries compared with developing countries, as a result of differential use of screening mammograms and disparities in lifestyle and hereditary factors. Future studies assessing the combined contributions of both environmental and hereditary factors may provide explanations for worldwide differences in incidence and mortality rates.

The idea of recording information on all cancer cases in defined communities dates from the first half of the twentieth century, and there has been a steady growth in the number of such cancer registries since. Originally, they were concerned primarily with describing cancer patterns and trends. Later, many were able to follow up the registered patients and calculate survival. In the last 20 years the role of registries has expanded further to embrace the planning and evaluation of cancer control activities, and the care of individual cancer patients. This Review looks at the current status of cancer registration practice and use from an international perspective, mindful that the registration of cancer has expanded into a global activity.

Cancer is rare before age 20 years. We aimed to use the European database of childhood and adolescent cancer cases, within the Automated Childhood Cancer Information System project, to estimate patterns and trends of incidence and survival within Europe. Comparable, high-quality data from 63 European population-based cancer registries consisted of 113000 tumours in children and 18243 in adolescents diagnosed in 1970-99. Incidence rates and survival were compared by region (east vs west), period, and malignant disease. In the 1990s, age-standardised incidence rates were 140 per million for children (0-14 years) and 157 per million for ages 0-19 years. Over the three decades, overall incidence increased by 1.0% per year (p<0.0001) in children (increases for most tumour types), and by 1.5% (p<0.0001) in adolescents (15-19 years; notable increases were recorded for carcinomas, lymphomas, and germ-cell tumours). Overall 5-year survival for children in the 1990s was 64% in the east and 75% in the west, with differences between regions for virtually all tumour groups; 5-year survival was much the same in adolescents. Survival has improved dramatically since the 1970s in children and adolescents, more so in the west than in the east. Our results are clear evidence of an increase of cancer incidence in childhood and adolescence during the past decades, and of an acceleration of this trend. Geographical and temporal patterns suggest areas for further study into causes of these neoplasms, as well as providing an indicator of progress of public-health policy in Europe.