The past few months I have seen too many reports of friends being affected by cancer. Cases roll in daily at the hospital, and though I can handle the workload, there are days when I see a folder and a name and wonder what they are dealing with personally. I have a friend that is on the brink of discovering what is going on with a possible diagnosis and another in Australia who is fighting for her life. My husband lost both of his parents and grandparents to cancer. I have another acquaintance back home dealing with cancer and younger than me, and then at church the other night heard about yet another case. Even my own mother has been diagnosed in the past. I am in tears, folks. I do not understand how it seems there are more cases in my life whether it is that I am growing older or that the article mentions cancer is on the rise. I have to agree. The International Agency for Research on Cancer, the specialized agency of WHO for cancer, has launched "World cancer report 2014". The report reveals prevention is key and that cases of cancer are growing at an alarming rate.
From the WHO website:
- Cancers figure among the leading causes of death worldwide, accounting for 8.2 million deaths in 2012 (1).
- Lung, liver, stomach, colorectal and breast cancers cause the most cancer deaths each year.
- The most frequent types of cancer differ between men and women.
- About 30% of cancer deaths are due to the five leading behavioral and dietary risks: high body mass index, low fruit and vegetable intake, lack of physical activity, tobacco use, alcohol use.
- Tobacco use is the most important risk factor for cancer causing over 20% of global cancer deaths and about 70% of global lung cancer deaths.
- Cancer causing viral infections such as HBV/HCV and HPV are responsible for up to 20% of cancer deaths in low- and middle-income countries (2).
- More than 60% of world’s total new annual cases occur in Africa, Asia and Central and South America. These regions account for 70% of the world’s cancer deaths (1).
- It is expected that annual cancer cases will rise from 14 million in 2012 to 22 within the next two decades (1).
The main types of cancer are:
- lung (1.59 million deaths)
- liver (745 000 deaths)
- stomach (723 000 deaths)
- colorectal (694 000 deaths)
- breast (521 000 deaths)
- oesophageal cancer (400 000 deaths) (1).
What causes cancer?
Cancer arises from one single cell. The transformation from a normal cell into a tumour cell is a multistage process, typically a progression from a pre-cancerous lesion to malignant tumours. These changes are the result of the interaction between a person's genetic factors and three categories of external agents, including:
- physical carcinogens, such as ultraviolet and ionizing radiation;
- chemical carcinogens, such as asbestos, components of tobacco smoke, aflatoxin (a food contaminant) and arsenic (a drinking water contaminant); and
- biological carcinogens, such as infections from certain viruses, bacteria or parasites.
WHO, through its cancer research agency, International Agency for Research on Cancer (IARC), maintains a classification of cancer causing agents.
Ageing is another fundamental factor for the development of cancer. The incidence of cancer rises dramatically with age, most likely due to a build up of risks for specific cancers that increase with age. The overall risk accumulation is combined with the tendency for cellular repair mechanisms to be less effective as a person grows older.
Risk factors for cancers
Tobacco use, alcohol use, unhealthy diet and physical inactivity are the main cancer risk factors worldwide. Chronic infections from hepatitis B (HBV), hepatitis C virus (HCV) and some types of Human Papilloma Virus (HPV) are leading risk factors for cancer in low- and middle-income countries. Cervical cancer, which is caused by HPV, is a leading cause of cancer death among women in low-income countries.
How can the burden of cancer be reduced?
Knowledge about the causes of cancer, and interventions to prevent and manage the disease is extensive. Cancer can be reduced and controlled by implementing evidence-based strategies for cancer prevention, early detection of cancer and management of patients with cancer. Many cancers have a high chance of cure if detected early and treated adequately.
Modifying and avoiding risk factors
More than 30% of cancer deaths could be prevented by modifying or avoiding key risk factors, including:
- tobacco use
- being overweight or obese
- unhealthy diet with low fruit and vegetable intake
- lack of physical activity
- alcohol use
- sexually transmitted HPV-infection
- urban air pollution
- indoor smoke from household use of solid fuels.
Tobacco use is the single most important risk factor for cancer causing about 22% of global cancer deaths and about 71% of global lung cancer deaths. In many low-income countries, up to 20% of cancer deaths are due to infection by HBV and HPV.
- Increase avoidance of the risk factors listed above.
- Vaccinate against human papilloma virus (HPV) and hepatitis B virus (HBV).
- Control occupational hazards.
- Reduce exposure to sunlight.
Cancer mortality can be reduced if cases are detected and treated early. There are two components of early detection efforts:
The awareness of early signs and symptoms (for cancer types such as cervical, breast colorectal and oral) in order to get them diagnosed and treated early before the disease becomes advanced. Early diagnosis programmes are particularly relevant in low-resource settings where the majority of patients are diagnosed in very late stages and where there is no screening.
Screening is defined as the systematic application of a test in an asymptomatic population. It aims to identify individuals with abnormalities suggestive of a specific cancer or pre-cancer and refer them promptly for diagnosis and treatment. Screening programmes are especially effective for frequent cancer types for which a cost-effective, affordable, acceptable and accessible screening test is available to the majority of the population at risk.
Examples of screening methods are:
- visual inspection with acetic acid (VIA) for cervical cancer in low-resource settings;
- PAP test for cervical cancer in middle- and high-income settings;
- mammography screening for breast cancer in high-income settings.
Cancer treatment requires a careful selection of one or more intervention, such as surgery, radiotherapy, and chemotherapy. The goal is to cure the disease or considerably prolong life while improving the patient's quality of life. Cancer diagnosis and treatment is complemented by psychological support.
Treatment of early detectable cancers
Some of the most common cancer types, such as breast cancer, cervical cancer, oral cancer and colorectal cancer have higher cure rates when detected early and treated according to best practices.
Treatment of other cancers with potential for cure
Some cancer types, even though disseminated, such as leukemias and lymphomas in children, and testicular seminoma, have high cure rates if appropriate treatment is provided.
2. de Martel C, Ferlay J, Franceschi S, et al. Global burden of cancers attributable to infections in 2008: a review and synthetic analysis. The Lancet Oncology 2012;13: 607-615.
I suppose it is time that instead of thinking it is caused by genetics and cigarettes alone, but sugar, high fat diets, low fruit and vegetable intake among the other risks listed above. I think it is time to change my diet.