A new research published in the medical journal Cancer Epidemiology, Biomarkers & Prevention analyzed the most recent trends of cancer rates. The results seem to point towards a general improvement in cancer rates in the Western world while the rest of the population appear to fare somewhat worse.
There aren’t many statistics that provide reliable data about worldwide cancer incidence and mortality trends, as much of this data only focuses on single countries.Lindsey A. Torre, an epidemiologist at the American Cancer Society and lead author of this study, checked together with her colleagues the data coming from the International Agency for Research on Cancer (IARC) Cancer Mondial database on cancer incidence and death rates for the years 2003-2007. The database also included mortality data through 2012 for 50 countries from selected regions that represent five continents, coming from a collaboration between the International Association of Cancer Registries and IARC, as well as data from the WHO Cancer Mortality Database.
Differences in reporting standards from one country to another provided a limitation to the study. For example, data collected in urban centers may not accurately represent regions where most of the population still lives off the countryside such as many African regions. Also in many countries registration of death in not mandatory, actually skewing mortality data.
The Results of the study
Data from the World Cancer Research Fund International showed that in 2012, 14.1 total patients suffered from cancer, with a slight prevalence for men (7.4 million cases) compared to women (6.7 million). This number, however, will increase to 24 million in twenty years. Lung cancer seems to be the most widespread worldwide, with 13% new yearly diagnoses, followed by breast cancer, accounting for 1.7 million new cases. Breast cancer is the most common women cancer, on the other hand, with over 25% new cancer cases, followed by cervical cancer accounting for nearly 8% of female cancers. Colorectal cancer counts approximately 1.4 million new cases and is thus the third most common cancer. These three types of malignancies alone account for almost half of all cancer types. Lung cancer is instead the most common men malignancy, covering almost 17% total new diagnosis in 2012. Together with colorectal and prostate cancers, it contributes to 42% of all cancers. Other common oncologic diseases were liver, esophageal, cervical and stomach cancers. These eight cancers accounted for 60% total cases of cancer and deaths.
According to the data provided by this study, in 2012, almost 8.2 million patients died because of cancer. Oncologic diseases represent the leading cause of mortality worldwide, regardless of the region or income level. The number of cancer cases diagnosed every year is expected to increase especially in LMIC, as the lifestyle behaviors adopted and overall population growth will increase cancer risk.
Differences between the various countries worldwide
Although the incidence rates for all sites as well as for breast, lung, prostate and colorectal cancer seems to be highest in high-income countries (HIC), the overall rates showed a general decrease. Some low- and middle-income countries (LMIC) instead now show higher cancer rates, and even count among those with the highest rates for some of the HIC cancer types. Cancer prevention and screening programs seem to be the principal responsible for improved cancer control in richer countries. An extensive effort in promoting healthier lifestyle changes to reduce risk factors such as bad dietary habits, overweight, lack of physical activity, smoking and alcohol consumption also contributed to the general improvement in cancer rates in these countries.
On the other hand, it seems that in low- and middle-income countries, these same risk factors typical of the Western lifestyle are increasing, leading to a higher prevalence of some particular types of cancer such as lung and colorectal cancer. Regional differences still play a critical role, however. For example, in South and South-East Asia betel leaves and areca nuts are chewed as mild stimulants although habitual high consumption may account for the higher percentage of oropharyngeal malignancies diagnosed in these regions.
Article by Dr. Claudio Butticè, PharmD.
1. Lindsey A. Torre, Rebecca L. Siegel, Elizabeth M. Ward, Ahmedin Jemal “Global Cancer Incidence and Mortality Rates and Trends—An Update”. Cancer Epidemiology, Biomarkers & Prevention, December 2015, 24 (12). doi: 10.1158/1055-9965.EPI-15-0578
2. Colditz, Graham A. The SAGE Encyclopedia of Cancer and Society (Second ed.). Thousand Oaks: SAGE Publications, Inc. ISBN 9781483345734.