The Obesity Epidemic and Cancer in Africa

Overweight and obesity have increased since the 1980s. It reached 37% for men and 38% for women in 2013. The situation worsened for children and adolescents in developed countries. Recent reports showed that African and other developing nations are not immune from the devastating obesity epidemic. Many studies revealed a relevant strong relationship between obesity and cancers such as esophageal, postmenopausal breast, colorectal and endometrial cancers. Obesity-related cancers have increased exceptionally in adolescents and young adults but decreased in more advanced ages. Currently, cancer care services in Africa are still limited despite the rising demand; therefore, access to them is relatively difficult for many cancer patients with low income. Considering the fact that some cancers may be preventable, we reviewed articles about obesity and cancer to highlight the magnitude of the problem and raise awareness among African leadership on the importance of cancer prevention measures targeting obesity.


The obesity epidemic
The number of obese children and adolescents (aged 5 to 19 years) in the World has increased ten times in the past 40 years, according to a newly published study by Imperial College London and the World Health Organization (WHO) 1 .
If the situation remains unchanged, the World will have more obese children and adolescents than underweight in less than 5 years.The study that was published in the Lancet a month ago, scrutinized weight and height measurements from about 130 million individuals of more than five years (31.5 million people aged 5 to 19 and 97.4 million aged 20 and older), the greatest known number of individuals included in a study.More than 1000 researchers played part in this famous study that stared at body mass index (BMI) and how obesity has evolved worldwide from 1975 to 2016.Within this period, obesity rates in the world's children and adolescents rose from less than 1% for both sex to14% in 2016 1 .
Obesity in children which decelerates in developed countries is rising in developing countries as an impact of unhealthy food marketing and lack of preventive policies 1 .

Obesity and cancer
The idea that obesity may cause cancer started in early 1930s after observing that over nutrition is frequent in cancer patients.It was postulated that excessive food intake may be the origin of malignancy 2 .In 1997, the World Cancer Research Fund / American Institute for Cancer Research published a first report on evidence between diet and cancer causal relationship 3 .
In 2002, the International Agency for Research on Cancer (IARC) published a report on the evaluation of cancer-preventive strategies, emphasizing on weight control and physical exercises 4 .Later, the WHO published another report focusing not only on nutrition and prevention of chronic diseases but also investigated the association of diet with cancer by evaluating causal relationship.There was strong evidence that obesity increases risk of colorectal cancer, postmenopausal breast cancer, endometrial cancer, renal cell carcinoma and adenocarcinoma of the esophagus.In addition, in 2003, another study reported that obesity was vigorously associated with cancer mortality and morbidity in men and women 5,6 .

Obesity in Africa
Obesity has also increased in African children, adolescents as well as adult people.Table 1 summarizes the age standardized obesity in some African Countries in 2013 7 .North African countries occupied the first place for the age patterns of obesity in 2013.The Age related obesity was different between men and women and between developing counties themselves.For African countries, women are more obese than men older than 25 old years.The highest level of obesity was observed at about age 55 years for women with 14.4% (13.5-15.5)rate, and about 45 years for men with 8•1% (7•5-8•80) rate 7 .The above mentioned findings correlate with the previously published data on obesity in Africa.Sub-Saharan Africa was also affected by the emerging obesity epidemic despite unstoppable malnutrition in many countries 8 .Obesity rates in females were observed in Sub-Saharan countries particularly in urban settings 9- 13 .It doubled in urban West African population in the past 10 years 14,15 .In addition, more than a half of South African women and nearly 30 % of men were overweight or obese in the past 17 years 16 .
The obesity increase in Africa is attributed to high calorie food intake, changes in diet composition especially fast foods consumption which are cheap and abundant, decreased physical exercises, sedentary life, and possible changes in the intestinal microbiome.Reducing unhealthy food marketing, strengthening surveillance, good public health practice and awareness increase may be valuable 7 .

Cancer care defect in Africa
The newly published preliminary analysis of colorectal cancer in South African urban settings revealed that colorectal cancer had a tendency to occur at the younger age at presentation in black South African people, the frequently encountered tumor location was the left colon and rectum.This confirmed the data published previously showing a difference in age at presentation and site of tumor according to ethnicity.Risk factors such as smoking and obesity remain significantly worrisome even in lower and middle income countries 17 .
Another published article retrospectively studied the risk factors of breast cancer in Bangui questioned overweight and obesity among the breast cancer behavior risk factors in the Central African Republic women living the capital 18 .
An Egyptian published study on BMI and breast cancer in Upper Egypt concluded that overweight and obesity were strongly associated with the later stages of breast cancer at diagnosis (stage III, IV).This may be related to lack of screening awareness of obese women.Additionally, the increased fats in obese women may have affected early breast cancer detection.Obese and overweight women with breast cancer in this study were more often older, with a significant p-value (p=0.002), which confirmed that excessive adipose tissue in postmenopausal women may raise the production of endogenous estrogen due to elevated production and activity of enzymes aromatase and 17β-hydroxysteroid dehydrogenase.Moreover, a decrease in the sex hormone-binding globulin due to obesity results in elevated formation of estrogen and testosterone which may accentuate the cellular proliferation and inhibit apoptosis in the breast 19 .
The African population cancer survival rate is far worse than the one of developed countries.For instance, the 5-year survival rate of breast cancer women in Europe is 82%, while it is 46% in Uganda, 39% in Algeria, and 12% in Gambia Available data revealed causes of cancer management defect in Africa and proposed some solutions to the shoddy outcomes.However, there is lack of clear targets and time frame work towards the needed success 20 .The WHO-Brazzaville Declaration on Non-communicable Diseases Prevention and Control in Africa recommended to raise awareness among Governments concerning noncommunicable diseases such as cancers.The declaration also emphasized on prevention, health system strengthening, budget provision and data generation 21 .
Among other problems revealed, there was lack of sufficient operational policies and cancer control plans which look after cancer control strategies, monitor cancer magnitude and provide cancer statistics and their country distribution [22][23][24][25] .
The updated GLOBOCAN report revealed that more than 850,000 new malignaces were diagnosed in Africa 15 years ago and within the same period 600,000 cancer related deaths occurred.And it was predicted that in 2020 the number of new cancers will be doubled 24 .
The most common cancers in Africa were breast cancer and cervical cancer in females and prostate cancer in males.Other common malignancies are lung, liver, colorectal, esophageal, non-Hodgkin's lymphoma, Kaposi sarcoma and other skin cancers.The annual crude cancer incidence in Africa was 79/100,000 people 25 .
Cancer care facilities in Africa are still limited, but through collaboration with the Organization for Research and Training in Cancer (AORTIC), up to 102 cancer centers were established.They provide clinical oncology, radiation oncology, medical oncology, pediatric oncology, palliative care and other organ specific oncologic services.Among the working centers almost a half of them is located in South Africa and Egypt.The defective surgical oncology services makes the problem more complicated and massive doctor's emigration to Europe is incriminated 26 .
Most of African countries don't have radiation therapy services which are considered to cure up to 40% of cancer patients.In developing, counties due to the Felix Sinzabakira & Samy Alsirafy Res Oncol.2018; 14(1): 2-5.

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defective surgical oncology services, radiation could treat up to 70% of new patients on palliative basis 27 .It was revealed that only 277 external beam radiation therapy machines were available in Africa 7 years ago and 60 % of them are located in Egypt and South Africa, at the same time 700 additional machines were needed to cover the gap.Unfortunately, for the time being a large number of newly presenting cancer patients in Africa do not have chance to access the health services adequately.Chemotherapy services that are available in Sub-Saharan Africa covers only the half of the demand .They were revealed to be generic and very expensive for many poor families 28 .
Pathology services and other diagnostic tool remain challenging.There are no available data about these important services in Africa.However, it was revealed that the number of pathologists in Africa is less than 10% the one of developed countries 29,30 .
Recent data for cancer prevention revealed that most of frequent malignancies in Africa are, predominantly, preventable.For instance, cervical cancer prevention is possible by human papilloma virus (HPV) vaccination, liver can be prevented by Hepatitis C prevention and Burkitt's lymphoma risk can be reduced by malaria eradication.In addition, the risk of Kapsi sarcoma and by prevented by HIV control and the risk of skin cancers by reducing sun light exposure.Unfortunately, the review revealed that the preventive measures in many African countries are still inadequate 31 .Add to these, the potential impact of obesity control on cancer prevention.

Conclusion
Cancer prevention pledges the most auspicious channel of minimizing cancer burden in many developing countries.To achieve that, we need to fight against known modifiable risk factors, such as obesity.If untrammeled, the obesity epidemic in Africa will significantly increase health and economic consequences, especially for those most vulnerable, poor people and the young generations.Implementation of potent mechanisms to address this epidemic is a worry of urgency on the African continent.