Oesophageal cancer in Africa: Nutrition is a significant risk factor

 
The Global Cancer Observatory (the World Health Organisation’s international agency for research on cancer) states that oesophageal cancer is “the 9^th most common cancer in the world, with over 300 000 new cases annually of which 80% occur in developing countries”.^[1] In Africa, where the incidence of oesophageal cancer is higher than the global average, researchers refer to the ‘African Oesophageal Cancer Corridor’ – an east African corridor “extending from Ethiopia to South Africa” ^[2], where both adenocarcinoma and squamous cell oesophageal cancer have a high prevalence. ^[3] In South Africa, for example, oesophageal cancer is responsible for the second highest number of cancer-related deaths ^[4]. (See Table 1, below, for a list of incidence rates of oesophageal cancer in selected African countries).

Aside from a genetic predisposition that is hypothesised to play a role ³, there are a number of diet- and lifestyle-related factors that have been associated with the high incidence of oesophageal cancer in Africa.

Risk factors demonstrate that healthy nutrition & lifestyle are critical

• A predominantly refined maize-based diet, with high use of refined maize meal as an affordable staple: Researchers have found a link between the incidence of oesophageal cancer and the easy availability of maize milling to subsistence farmers. ^[5] Similarly, there is a higher prevalence of cancer in low-income populations, which rely on maize-meal as a staple. It is believed that diets heavy in refined maize meal are deficient in healthy nutrients that reduce the risk of cancer. ⁵
• Nutritional deficiency: A deficiency of vitamins A, E, and B₁₂, as well as folate and selenium is associated with oesophageal cancer. ^{[6] & [7]}
• Heavy use of tobacco: Studies have shown that heavy smokers (or those that have smoked for prolonged periods, from a young age) are at greater risk of oesophageal cancer. ^[8]
• Obesity: This is a risk factor associated with the development of oesophageal cancer in both men and
  women. ³
• High cholesterol: A high cholesterol diet has been found to “significantly increase the risk of developing oesophageal cancer”. ^[9] It is regarded as a risk factor for both men and women. ³
• Alcohol use: Researchers believe that alcohol is a major contributor to the risk of oesophageal cancer in Africa (especially among men). ^[10]
• Pre-existing conditions: These may increase the risk of oesophageal cancer. These conditions include GORD (gastroesophageal reflux disorder) and Barrett’s Oesophagus (which causes long-term reflux of stomach acid into the oesophagus), as well as other types of cancer. ^[11]

Interventions to remedy the problem

A number of research-based interventions are proposed to address these risk factors, and in so doing, reduce the high incidence of oesophageal cancer.

• The formulation of national policy to address cancer, and a strategic plan to support the policy. ¹²
• The implementation of interventions to monitor and address obesity and metabolic syndrome (a significant risk factor for oesophageal cancer as well as cardiovascular disease). ³
• Improving access to healthcare, and in particular, to early detection screening. This would promote early diagnosis and improve the prognosis.³ The integration of these interventions into existing community healthcare services is key. ¹²
• Interventions that control alcohol consumption (especially harmful alcohol), by targeting drinking habits and educating individuals about the risks of unmoderated alcohol consumption. ^{3, 5 & 10}
• Supporting cancer research. ¹²
• Interventions that educate populations about the risks associated with smoking tobacco, including education programmes for school children. ^[12]
• Fortification of staple foods (such as maize meal) with vitamins and minerals. ⁵

The role that HCPs can play in the prevention and management of oesophageal cancer in Africa

Oesophageal cancer has a higher prevalence in men, with the World Cancer Research Fund (WCRF) finding that oesophageal cancer is the “7^th most commonly occurring cancer in men and the 13^th in women.” ^[13] Usually, oesophageal cancer begins in the cells lining the interior of the oesophagus but does not cause signs or symptoms during the early stages. ^[14] It is an aggressive form of cancer, and even when diagnosed (often only when it has advanced considerably), treatment options are limited. ^[15] As a result, this cancer has one of the highest mortality rates, and is responsible for more than 500 000 deaths annually. ³

Pertinently, the key risk factors are all manageable, via dietary and lifestyle interventions. This HCPs are well-positioned to provide reliable advice to patients, for the prevention of cancer. The recommendations include ⁹:

• Maintaining a healthy weight through diet and exercise
• Eating a diet rich in a variety of vitamins as well as macro- and micro-nutrients
• Avoiding unhealthy cholesterols
• Quitting smoking and avoiding chewing tobacco
• Consuming alcohol in moderation

 
Patients should be educated about the risk factors and informed of the symptoms of oesophageal cancer (see below). High-risk patients should be encouraged to go for screening, regularly.

Symptoms of oesophageal cancer ^{[14] & [16]}

• Difficulty swallowing (dysphagia)
• Weight loss without trying
• Chest pain, pressure or burning
• Worsening indigestion or heartburn
• Coughing or hoarseness
• Coughing up blood
• Dark or bloody stool

Table 1: Age-standardized incidence rates of oesophageal cancer in selected African countries. ^[17]