Cancer constitutes an enormous burden on society in more and less economically developed countries alike. The occurrence of cancer is increasing because of the growth and aging of the population, as well as an increasing prevalence of established risk factors such as smoking, overweight, physical inactivity, and changing reproductive patterns associated with urbanization and economic development. Based on GLOBOCAN estimates, about 14.1 million new cancer cases and 8.2 million deaths occurred in 2012 worldwide. Over the years, the burden has shifted to less developed countries, which currently account for about 57% of cases and 65% of cancer deaths worldwide. Lung cancer is the leading cause of cancer death among males in both more and less developed countries, and has surpassed breast cancer as the leading cause of cancer death among females in more developed countries; breast cancer remains the leading cause of cancer death among females in less developed countries. Other leading causes of cancer death in more developed countries include colorectal cancer among males and females and prostate cancer among males. In less developed countries, liver and stomach cancer among males and cervical cancer among females are also leading causes of cancer death. Although incidence rates for all cancers combined are nearly twice as high in more developed than in less developed countries in both males and females, mortality rates are only 8% to 15% higher in more developed countries. This disparity reflects regional differences in the mix of cancers, which is affected by risk factors and detection practices, and/or the availability of treatment. Risk factors associated with the leading causes of cancer death include tobacco use (lung, colorectal, stomach, and liver cancer), overweight/obesity and physical inactivity (breast and colorectal cancer), and infection (liver, stomach, and cervical cancer). A substantial portion of cancer cases and deaths could be prevented by broadly applying effective prevention measures, such as tobacco control, vaccination, and the use of early detection tests.

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Global cancer statistics, 2012

While incidence and mortality rates for most cancers (including lung, colorectum, female breast, and prostate) are decreasing in the United States and many other western countries, they are increasing in several less developed and economically transitioning countries because of adoption of unhealthy western lifestyles such as smoking and physical inactivity and consumption of calorie-dense food. Indeed, the rates for lung and colon cancers in a few of these countries have already surpassed those in the United States and other western countries. Most developing countries also continue to be disproportionately affected by cancers related to infectious agents, such as cervix, liver, and stomach cancers. The proportion of new cancer cases diagnosed in less developed countries is projected to increase from about 56% of the world total in 2008 to more than 60% in 2030 because of the increasing trends in cancer rates and expected increases in life expectancy and growth of the population. In this review, we describe these changing global incidence and mortality patterns for select common cancers and the opportunities for cancer prevention in developing countries.

https://cebp.aacrjournals.org/content/cebp/19/8/1893.full.pdf

Global Patterns of Cancer Incidence and Mortality Rates and Trends

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(13)62218-7.pdf

Efficacy of HPV-based screening for prevention of invasive cervical cancer: follow-up of four European randomised controlled trials

BACKGROUND: Baseline information on human papillomavirus (HPV) prevalence and type distribution is highly desirable to evaluate the impact of prophylactic HPV vaccines in the near future. METHODS: A meta-analysis was performed of studies published between 1995 and 2009 that used polymerase chain reaction or Hybrid Capture 2 for HPV detection in women with normal cytological findings. RESULTS: The analysis included 194 studies comprising 1016719 women with normal cytological findings. The estimated global HPV prevalence was 11.7% (95% confidence interval 11.6%-11.7%). Sub-Saharan Africa (24.0%) Eastern Europe (21.4%) and Latin America (16.1%) showed the highest prevalences. Age-specific HPV distribution presented with a first peak at younger ages ( /=45 years). Among the women with type-specific HPV data ([Formula: see text]) the 5 most common types worldwide were HPV-16 (3.2%) HPV-18 (1.4%) HPV-52 (0.9%) HPV-31 (0.8%) and HPV-58 (0.7%). CONCLUSIONS: Although the prevalence of HPV in women with normal cytological findings is high and variable across world regions HPV types 16 18 31 52 and 58 are consistently found among the 10 most common types in all of them. These results represent the most comprehensive assessment of HPV burden among women with normal cytological findings in the pre-HPV vaccination era worldwide.

Cervical Human Papillomavirus Prevalence in 5 Continents: Meta-Analysis of 1 Million Women with Normal Cytological Findings

Worldwide burden of cervical cancer in 2008

In the HPV-testing group, cervical cancer was diagnosed in 127 subjects (of whom 39 had stage II or higher), as compared with 118 subjects (of whom 82 had advanced disease) in the control group (hazard ratio for the detection of advanced cancer in the HPV-testing group, 0.47; 95% confidence interval [CI], 0.32 to 0.69). There were 34 deaths from cancer in the HPV-testing group, as compared with 64 in the control group (hazard ratio, 0.52; 95% CI, 0.33 to 0.83). No significant reductions in the numbers of advanced cancers or deaths were observed in the cytologic-testing group or in the VIA group, as compared with the control group. Mild adverse events were reported in 0.1% of screened women. Conclusions In a low-resource setting, a single round of HPV testing was associated with a significant reduction in the numbers of advanced cervical cancers and deaths from cervical cancer.

Ashok Kothari

Papers

HPV screening for cervical cancer in rural India.