International Agency for Research on Cancer: The number of cancer patients doubles in the next 50 years, three points are essential for prevention and control

Currently, cancer is the leading or second most common cause of premature death in most countries in the world
.

Due to factors such as population aging and population growth, it is expected that the number of cancer patients in the world will continue to increase in the next 50 years

In a recent article published in Nature Reviews Clinical Oncology under Nature, a research team from the International Agency for Research on Cancer (IARC) estimated the burden of cancer in the next 50 years and the impact of comprehensive prevention strategies on the number of cancer cases in the future
.

The article pointed out that if the current trend is to develop, the annual new cancer cases will reach 34 million by 2070, which is double the data in 2020; and in the comprehensive cancer prevention strategy, the main cancer risk factors, such as smoking and overweight Obesity and high-risk human papillomavirus (HPV) infection will be the top priority for prevention and control
.

Future cancer burden forecast

Future cancer burden forecast

Based on the IARC global database, the "Cancer Incidence in Five Continents" (Cancer Incidence in Five Continents) published continuously since 1996, as well as demographic changes (fertility rate, immigration, and life expectancy) and changing trends in risk factors, the research team predicts:

The absolute burden of global cancer is rising, and 34 million new cancers are expected to occur by 2070, twice the estimated number in 2018
.

Mainly driven by demographic changes, changes in risk factors have little impact

Although countries with high Human Development Index (HDI) have the largest absolute increase, countries with low HDI have the most relative growth (400%), and countries with extremely high HDI have the least relative growth (53%).

▲Expected changes in new cases of all cancer types in the world in 2070, divided by HDI
.

The blue part is compared with the increase in 2018, and the arrow represents the increase/decrease of the cancer burden caused by the change of risk factors (picture source: reference [1])

The largest increase is expected to be breast cancer and colorectal cancer.
Population changes and rising incidence will result in 4.
7 million new cases and 4.
4 million new cases in 2070 (1.
8 million and 2.
1 million cases respectively in 2018)
.

Next is lung cancer, with 3.

The incidence of cervical cancer and gastric cancer is declining and stabilizing globally
.

The burden of cervical cancer varies significantly in different regions
.

In countries with a medium to extremely high human development index (HDI), the decline in the incidence of cervical cancer will offset the population impact, and the overall number of cervical cancers will drop from 484,000 cases in 2018 to 409,000 cases in 2070; at the same time , The incidence of cervical cancer in countries with the lowest HDI will increase by 150%, from 84,000 cases in 2018 to 212,000 cases in 2070

▲The trend of the number of new cases of major cancers in the world from 2018 to 2070, from top to bottom are colorectal cancer, breast cancer, lung cancer, prostate cancer, gastric cancer and cervical cancer
.

(Image source: Reference [1])

Three effective measures to prevent cancer

Three effective measures to prevent cancer

The causes of different cancers are diverse, the incubation period of the disease is long, and the benefits of effective preventive interventions usually take many years to be observed
.

Considering the importance of targeted interventions, the study focused on analyzing data from areas where the prevalence of known risk factors is high and the burden of specific cancer types is high, and focused on the three categories of tobacco control, obesity prevention and control, and HPV vaccination and screening The impact of measures on the incidence of cancer

1.
Tobacco Control

From 1990 to 2015, although the overall global smoking rate dropped significantly, from 34% to 25% for men and from 8% to 5% for women, the prevalence of tobacco in low- and middle-income countries stabilized and the incidence of tobacco-related cancers The rate continues to increase, and the overall reduction in the global tobacco-related cancer burden is not obvious
.

More than 14% of cancers worldwide are caused by smoking
.

In addition to lung cancer, there are at least 15 other types of cancer related to smoking, including oral cancer, nasopharyngeal cancer, oropharyngeal cancer, nasal cavity cancer and paranasal sinus cancer, laryngeal cancer, esophageal cancer, gastric cancer, pancreatic cancer, colorectal cancer, Liver cancer, kidney cancer, ureteral cancer, bladder cancer, cervical cancer and ovarian cancer, and myeloid leukemia

It is currently estimated that about 2.
8 million cancers worldwide are related to smoking a year
.

If there is no change in current tobacco control, the research team estimates that by 2070, there will be more than 4 million new cancer cases globally attributable to smoking

Therefore, ensuring the implementation of tobacco control measures is a key driver for substantially reducing the burden of cancer in the future
.
A number of studies have shown that when comprehensive tobacco control measures are taken, the effect of reducing related cancers will be much more pronounced than a single strategy
.

Indonesia is one of the ideal samples for evaluating the effectiveness of tobacco control
.
Indonesia is the fourth most populous country in the world and one of the countries with the highest proportion of male smokers.
In 2015, more than 70% of current male smokers in the country were over 15 years old.
The current smoking rate has not declined, and tobacco control activities are weak
.
The research team estimates:

Among the 3.
2 million cases of lung cancer projected in Indonesia from 2018 to 2070, raising tobacco prices can prevent about 15% of the cases;

Implementing a comprehensive tobacco control plan (including implementing a smoke-free policy, improving health warnings on tobacco packaging, strengthening media publicity, and promoting smoking cessation treatment, etc.
) can help prevent an additional 5% (160,000) of lung cancer;

Of these preventable cancer cases, 94% are male cases
.

2.
Obesity prevention and control

In the past few decades, the global prevalence of overweight and obesity (BMI≥25 kg/m2) has increased significantly
.
Overweight and obesity are known risk factors for at least 10 cancers, including esophageal adenocarcinoma, cardia cancer, colon cancer, rectal cancer, liver cancer, gallbladder cancer, pancreatic cancer, postmenopausal breast cancer, uterine cancer, and renal cell carcinoma
.

In 2012, at least 500,000 (3.
6%) cancers worldwide were attributed to overweight and obesity
.
If the BMI of the global population continues to grow linearly between 2018 and 2030, even if this growth rate slows down by 25%, 50%, and 75%, respectively, every 10 years in the future, until the BMI reaches a stable level, it is estimated that the global population will exceed 2 million by 2070.
Cases of cancer (7% of all predicted cancer cases) are attributable to obesity
.

Although the number of cases that can actually be avoided through public health interventions is not sufficient in existing studies, reducing BMI has a moderate potential impact on the burden of cancer
.

For example, a study conducted in five Nordic countries showed that if the proportion of overweight and obese people decreases by 1% and 2% each year, in 2016-2045, an estimated 204,000 cases of cancer attributable to overweight and obesity , 13,000 cases can be prevented
.

The Mexican population is one of the typical samples
.
In 2017, about two-thirds (>50 million) of the population were overweight and obese.
The country has formulated a series of national programs to prevent and control obesity, such as increasing the supply of healthy food and reducing sugar consumption
.
In 2018, there were about 10,000 new cases of colon cancer in Mexico, about 15% of which can be attributed to high BMI (≥25 kg/m2)
.

If the intervention is successful in the next 10 years, the average BMI of the Mexican population will fall back to the 1990 level (that is, the BMI of men will be reduced from 27 kg/m2 to 25 kg/m2, and the BMI of women will be reduced from 28 kg/m2 to 26 kg/m2).
It is expected that 2018- In 2070, the number of colon cancer cases will be reduced by 110,000, and business as usual will total 1.
7 million
.

If the BMI of both sexes is gradually reduced by 1 kg/m2 every ten years from 2018 to 2070, about 165,000 cases of colon cancer can be prevented in total, and the burden of colon cancer in the local area will be reduced by nearly 10%
.

All in all, we need to take comprehensive actions, including food consumption interventions, promotion of healthy diet and physical activity, personal hygiene services, and clinical interventions to avoid overweight and obesity that will bring a huge cancer burden
.

3.
HPV vaccination and cervical cancer screening

In 2018, there were an estimated 570,000 newly diagnosed cases of cervical cancer and 311,000 deaths worldwide
.
The prevalence of cervical cancer varies greatly in different countries.
Part of the reason is that the prevalence of high-risk HPV strains, the coverage of HPV vaccines, and the coverage of screening programs are different
.
The WHO calls for the promotion of HPV vaccination and HPV screening for early detection to prevent cervical cancer
.

The research team used Uganda as a sample for analysis
.
A model study published in The Lancet in 2020 estimated that only 2.
7% of local women aged 10-20 received full vaccination in 2014
.
In the next 50 years, compared with the predicted value of no action, achieving a 90% HPV vaccination coverage will reduce the cumulative local cases by 40%; screening women once or twice in their lifetime will make The cumulative number of local cases has been reduced by 52% and 60%, which is equivalent to avoiding 550,000 and 630,000 cumulative cases, respectively
.
It is worth noting that increasing the screening program will accelerate the reduction of the incidence of cervical cancer: by increasing the once-in-a-lifetime screening, the time limit for elimination of cervical cancer is expected to be 5 years ahead of schedule, two screenings in a lifetime, and even 15 years in advance of the elimination of cervical cancer
.

The "Lancet" model study also emphasizes that under the combined effect of the triple intervention measures of vaccination, HPV screening and timely treatment, about 300,000 women will be prevented from dying of cervical cancer in 2030, which is equivalent to a reduction of 34.
2%.
Death from cervical cancer
.
By 2070, 14.
6 million deaths can be avoided and the mortality rate will be reduced by 92.
3%
.

In 2018, an estimated 690,000 cancers worldwide (4% of all cancer diagnoses) can be attributed to all subtypes of HPV infection, of which 80% (570,000 cases) are cervical cancer
.
Among other HPV-related cancers, the proportion of cancers caused by HPV varies greatly, ranging from 2% of oral cancers to about 100% of anal cancers
.

Since there is currently no effective screening plan for other HPV-related cancers, the effect of HPV vaccination on the prevention of other HPV-related cancers is also worth looking forward to
.
A study showed that the bivalent vaccine against HPV16 and HPV18 effectively reduced the prevalence of HPV in multiple sites (cervix, anus, and oral area) by 83.
5%
.

Preventive measures implemented

Preventive measures implemented

The study also emphasized that the evidence of cancer prevention continues to accumulate, and the next perfect prevention implementation is the key
.
However, when formulating and implementing these preventive measures, it is necessary to consider the differences in local health care systems and infrastructure, as well as socio-cultural and economic diversity, to help different groups of people in a targeted manner and to ensure that all groups can benefit from the prevention plan
.

For example, in the prevention and control of obesity, people generally believe that urbanization is the main determinant of negative health outcomes, but in fact, the observation results are contrary to intuition.
Overweight and obesity in rural areas are increasing
.

summary

summary

The study concluded that many common types of cancer can be prevented, and cancer prevention needs to be viewed from a long-term perspective: short-term prevention efforts will greatly reduce mortality and improve survival in a few decades
.

Note: The original text has been deleted

Reference materials:

[1] Soerjomataram, I.
, Bray, F.
Planning for tomorrow: global cancer incidence and the role of prevention 2020–2070.
Nat Rev Clin Oncol (2021).
https://doi.
org/10.
1038/s41571-021- 00514-z

[2] Planning for tomorrow: global cancer incidence and the role of prevention 2020–2070.
Retrieved July 5, 2021, from https:// cancer-incidence-and-the-role-of-prevention-2020-2070/