The world will likely witness a significant increase in new cancer cases and deaths by the end of the next decade. The most recent projections from the World Health Organization’s International Agency for Research on Cancer (IARC), which is responsible for investigating the causes of cancer and producing international statistics, suggest that the total number of new cases per year is going to rise by 56%, jumping from 19 million in 2020 to 30 million in 2040. Deaths are expected to rise from 10 million to 16.3 million in the same period. The increase in cases in Brazil is likely to be almost 70% and in deaths, 80%. “No nation is prepared to deal with the tsunami of cancer cases coming in the next few decades,” Brazilian epidemiologist Elisabete Weiderpass told Pesquisa FAPESP.
Weiderpass, the first woman to head the IARC, was born in Santo André, part of the São Paulo Metropolitan Area, and chose to study medicine at the Federal University of Pelotas (UFPel), drawn to the ideas of Brazilian public health expert Kurt Kloetzl (1923–2007), who founded the institution’s Department of Social Medicine. After doing an internship at IARC, Weiderpass went on to study a PhD at Karolinska Institutet in Sweden, where she would later become a professor. In 2019, she was named director of the WHO’s cancer research agency, a position to which she was reappointed for a further five-year term last May. As head of IARC, she intends to increase scientific exchanges with researchers from Brazilian institutions.
Aged 57 and married to Finnish toxicologist Harri Vainio, Weiderpass has published a huge volume of scientific work and hopes to help establish universal access to early cancer detection and basic treatment. On July 17, while taking part in an event at the São Paulo State Cancer Institute (ICESP), she spoke to Pesquisa FAPESP about the projected increase in cases and how we might prevent a large proportion of them by reducing exposure to risk factors such as tobacco and alcohol.
According to IARC’s most recent projections, new cases of cancer worldwide are expected to rise from 19 million in 2020 to 30 million in 2040. What is behind this jump?
Above all, it is the growth of the global population in absolute numbers. But it is also related to the aging population. A person born in any given year has an average life expectancy two months longer than people born the previous year. Over 10 or 20 years, this longevity becomes significant. Cancer is primarily a disease of the elderly—the average age of diagnosis is 66. In many countries, the life expectancy is just starting to reach this sort of age range. These countries are seeing a substantial increase in cancer cases. The annual incidence [number of new cases] is also influenced by exposure to risk factors, which vary from one region to another. The most influential factor is smoking. Tobacco consumption in its various forms is directly responsible for around 20% of cancer cases worldwide and is still rising in some regions, particularly among women.
The increase will not be homogeneous. What is the situation like in Brazil?
The rise or fall in incidence and mortality is different in every region of the world, just as the most common types of cancer vary from one to another due to differing patterns of exposure to risk factors. Brazil is expected to see an increase of almost 70% in the number of cases per year by the end of next decade, rising from 592,000 in 2020 to almost 1 million in 2040. Mortality is expected to increase by 80%, from 260,000 to 470,000. In the poorest countries, cases and deaths could increase by as much as 400%. No nation is prepared to deal with the tsunami of patients that is likely going to occur.
Cancer is currently the second leading cause of death worldwide, with 10 million deaths in 2021. Will it be the top killer in the future?
It will be the leading cause of death in all countries by the end of the century, especially premature deaths, meaning those that occur before the age of 70 and would, in principle, be preventable. In at least 55 countries, cancer is already the number one cause of premature death. Cancer mortality is expected to result in stagnating life expectancy around the world.
The projections in the World Cancer Report 2020 indicate that in a few decades, 75% of cancer deaths will occur in low- and middle-income countries. What are the reasons for that?
Asia currently accounts for half of the world’s cancer cases and 58% of deaths. Europe represents 23% of cases and 19% of deaths; in the USA, 21% of cases and 14% of deaths; in Latin America and the Caribbean, 8% and 7%; and in Africa, 6% and 7%. There is a clear difference between incidence and mortality. The incidence depends on the size, age, and life expectancy of the population. Mortality, however, is influenced by the type of health system available and the etiology of the cancers. In Africa and Asia, most cancers still result from infectious diseases and are very aggressive. In India, there is a lot of mouth cancer associated with tobacco use. People there spend the day chewing on tobacco leaves. It’s a habit that starts in childhood and lasts for decades. When the cancer is diagnosed, it is so advanced that there is no way to cure it.
We carried out a study in France that showed that 40% of all cancer cases could be prevented by existing feasible measures
Is there a cultural influence on exposure to risk factors?
There is a cultural factor, but it is secondary to the impact of a country’s laws and how well educated the public is about preventing cancer. The adoption of carcinogenic lifestyles associated with tobacco and alcohol consumption is influenced by legislation and its enforcement, in addition to taxation. The percentage of smokers in the world increases or decreases in response to the implementation of laws and controls on using these products. The only international treaty on this issue negotiated by the WHO is the 2003 Framework Convention on Tobacco Control, of which Brazil is a signatory. It includes several recommendations on protecting the public from the consequences of tobacco consumption and exposure. But most countries do not follow them as they should.
What is your opinion on the antismoking measures adopted in Brazil?
Brazil is taking important steps to prevent smoking, but not all of the convention’s recommendations have been implemented. The price of cigarettes is still relatively low. There is scope to increase the price through taxation, which would further limit access. You can also restrict sales locations and times and make changes to the packaging, such as prohibiting brands from being displayed. Australia and Canada are implementing the WHO convention more effectively and the phrase “cigarettes kill” is now printed on the side of every single cigarette. In these countries, the packaging was already totally blank. Despite the steps taken in Brazil, the incidence of lung cancer is still on the rise. What has been done so far is important, but there is a long way still to go.
What about alcohol?
This is a major cancer risk factor, but the general population and some medical professionals are unaware of this fact. A study we did in France, which was replicated in Brazil, showed that 40% of all cancers there can be prevented by measures that we are already aware of and that are fully implementable if the political will exists to drastically reduce the problem. Eliminating tobacco consumption would prevent 20% of cancer cases in France. The second biggest risk factor was alcohol, responsible for 8% of cases. These are not negligible percentages, but many medical professionals are still unaware that alcohol causes tumors in the esophagus, liver, and breast, in addition to colorectal, oral cavity, and pharyngeal cancer. Until recently, the medical community frequently stated that alcohol had cardiovascular benefits. But the latest research contradicts this idea [see Pesquisa FAPESP issue nº 327].
How is Brazil doing with regard to regulating the sale and consumption of alcohol?
I don’t know the details. What we can see is that alcohol is sold everywhere, with almost no restrictions, and age controls are not strictly adhered to. Consumption is accepted in all social groups. There is a long way to go to make the medical profession aware of the risks linked to this consumption, particularly among young people.
Some WHO data indicated that 30% to 40% of cancer cases could be prevented. For which types of cancer does prevention work best?
That figure is more like 40% to 50%, depending on the country. An article published in 2018 showed the percentage that can be prevented from each type of cancer. For cervix cancer, for example, it is almost 100%. For lung cancer, more than 90%. For others, the number is lower.
How can we convince decision makers that prevention is the best approach?
Short-, medium-, and long-term actions need to be implemented. One is health literacy. If you ask people what causes cancer, they don’t know the answer. Most will say cigarettes but stop there. There are 12 forms of exposure that occur in everyday life and can cause cancer. Smoking, alcohol consumption, a diet low in fruits, vegetables, and fiber, exposure to intense sunlight, and more. It is essential to teach people these things from an early age. When they are sufficiently informed about the risks and better equipped to protect themselves, they adapt their exposure to risks to a certain extent. At a governmental level, cost-effective measures can be adopted, such as reducing tobacco and alcohol consumption, in addition to vaccinating against the HPV virus.
This creates conflict with industry.
A continuous and bloody conflict. The pesticide, herbicide, and ultra-processed food industries attack the IARC on a daily basis. The soft drinks industry too, since mid-July. Their tactics for demoralizing science are well known. When studies began to show that smoking kills people, the tobacco industry began intense efforts to spread doubt. It claimed the studies were poorly conducted, were insufficient, or that there was some form of scientific controversy. Another tactic is to hire scientists to produce studies that reject the evidence of cancer risks. The industry has also managed to place individuals in universities, government ministries, and regulatory agencies. The same strategy was used by the perchlorate [compounds used in non-stick coatings], processed meat, and alcohol industries. It is currently being adopted by the soft drink industry in response to an article we published in Lancet Oncology on July 14 that suggested that aspartame, a synthetic sweetener used in soft drinks, may possibly be carcinogenic.
New treatments create hope for certain types of cancer, but they are still experimental and not available to the public
The IARC has already classified more than a thousand cancer risk factors. Which are the most dangerous?
Tobacco is number one. Other group 1 factors for which there is sufficient evidence that they cause cancer include solar radiation, the consumption of alcohol and processed meat, and exposure to benzene, ionizing radiation, atmospheric pollution, and asbestos. In group 2a, which means they potentially cause cancer, is the consumption of red meat and food fried at high temperatures, and exposure to glyphosate, DDT, and several other chemicals. Aspartame falls into group 2b—substances that may possibly cause cancer—alongside exposure to gasoline vapors and electromagnetic emissions in the radio frequency range. The complete list is available on the website iarc.who.int.
A 2022 study indicates that cancer rates in people under 50 is increasing. Why?
We have observed this phenomenon in several countries, especially in relation to colorectal cancer. One hypothesis is that it is a consequence of obesity and diet.
How does income inequality influence cancer incidence and outcomes?
Socioeconomic level is a key element when defining incidence and mortality. In a study published in Lancet Regional Health in 2022, we found that the incidence of cervical cancer varies little between women with medium and high socioeconomic status in the European Union. In women with a low income, however, there is a huge difference. This is a pattern that occurs worldwide: in the poorest areas, incidence and mortality are higher.
What explains this pattern?
The obvious suspects. Greater exposure to risk factors, such as tobacco and alcohol, inadequate diet, obesity, lack of physical activity, occupational exposure, and atmospheric pollution. Other reasons include less access to early screening for various types of cancer, late admission to the healthcare system, and lower adherence to treatment. This is repeated all over the world.
What is the solution?
Health policies that take social inequalities into account. Poorer people have less access to information and less of an understanding about carcinogenics. They also have greater difficulty identifying symptoms and seeking health services. Even with universal healthcare access in Brazil via the country’s national health system (SUS), this difference in incidence and mortality still exists. It is not a problem exclusive to any one country. Healthcare has to be adapted to the needs of less privileged populations.
What is your opinion on advances in cancer detection and treatment in recent decades?
There has been an improvement, and we are seeing a reduction in incidence and mortality in many countries as a result. This is mainly due to advances in prevention, which is what has the biggest impact, but also in earlier diagnosis and better access to effective treatments. Screening has really helped reduce cervical and breast cancer, as well as some forms of leukemia, but its success is still limited for tumors of the lungs, pancreas, esophagus, stomach, and brain. Most of the time, these cancers are detected late, when metastasis has already occurred.
What do you think of the latest treatments?
They are promising. They are a source of hope for some types of cancer. The most interesting is for melanoma, the most aggressive type of skin cancer. So-called targeted therapies have increased survival for most patients. But they are still experimental and not available to everyone. We will not see an immediate impact on mortality.
In 2022, we interviewed oncologist Chi Van Dang, scientific director of Ludwig Cancer Research in New York, who was optimistic and said he envisions a cancer-free future. What is your view on this?
I’m glad to hear he has such an optimistic outlook. Mine is tempered by the situations in the countries I visit. The path ahead of us is long and the challenge is immense. I’m not even talking about advanced therapies, just about early detection and access to basic treatment. Radiotherapy and chemotherapy are not available in many countries. In some places, there are no pathologists. My dream is for everyone to have access to screening, early detection, and basic treatment as a minimum human right. More than developing cutting-edge therapies, the challenge is to organize health systems to meet the demands of a growing and aging population.
What are the priorities in cancer research?
Today, most oncology funding is invested into research on advanced treatments. This is an important field, but unlikely to reduce mortality. New therapies generally extend life by days or weeks. If I had a magic wand, I would put a substantial proportion into prevention, which saves a greater number of lives, and I would increase research on how to implement the prevention possibilities that we already know about.
