New cancer cases have been increasing in the West. Those that top the list are breast, prostate, and lung cancer, with colorectal cancer (CRC).
A new study in Scientific Reports attempts to estimate the reduction in prevalence that could be accomplished by rigorously applying all known preventive measures against cancer.
Study: Non-preventable cases of breast, prostate, lung, and colorectal cancer in 2050 in an elimination scenario of modifiable risk factors. Image Credit: fizkes/Shutterstock.com
Background
The researchers used the Nordic cancer statistics database NORDCAN to arrive at their results. Previous predictions for Nordic countries showed an increase in new cases by over a quarter, with the highest spike being shown by CRC at ~30% above the 2021 levels.
Cancers are long-term and exacting health issues that require intensive and prolonged healthcare. Thus, it is important to build in cancer capacity into existing healthcare systems if the cancer burden is expected to rise.
The current study explored the ability of preventive actions to minimize or eliminate the increase in cancer risk. These included the Big Three, namely, quitting smoking, managing excessive body weight, and reducing alcohol consumption to acceptable levels.
Earlier studies indicated that attention to just one risk factor at a time could help prevent about 15% of new cancers over the next three decades. A later study linked a third of all cancers in the USA to these three factors.
Yet, the biggest risk for cancer remains age, particularly for epithelial cancers. As the aging population shoots up, especially in Nordic countries where the fertility rate is below the net replacement rate, there will be a 34% rise in the number of people aged 65 years or more. This age group contributes to two of every three cancers in Denmark.
Statistics Denmark says that the number of those aged at least 80 is expected to double by 2050 from 2020 levels.
Using three scenarios, the investigators modeled the effects of targeting these three risk factors. In each case, the first scenario was a no-change assumption. The second and third were reducing the exposure by half and eliminating it altogether, beginning in 2022.
They then estimated the number of new cases of each of Denmark's four most common cancers. A macrosimulation model called Prevent developed different estimates for each prevention scenario.
The researchers categorized exposures, such as light, moderate, and heavy drinking, for alcohol consumption (one or less drink per day, 1-4 per day, and > four drinks a day, respectively).
What were the effects of prevention?
The model projected an increase in prostate cancer by 25% in 2050 relative to 2020, with a ~20% rise in breast cancers. The highest increase was for CRC in women, at 33%, and CRC in men, by ~39%.
CRC in men and women could fall by ~28% and 16%, respectively, in 2050 if all three risk factors were no longer in play from this moment onwards.
Postmenopausal breast cancers would go down by 15%, while prostate cancer showed no change. The latter finding is predictable since these risk factors play no role in the etiology of prostate cancer.
Without such preventive measures, there was an estimated 25% increase in expected new prostate cancer patients.
Lung cancer incidence was predicted to fall by ~17% in both sexes. If smoking were instantly eliminated, the greatest possible reduction in new cases of lung cancer by 2050 would be by 70% in both sexes. At least 75% of new lung cancers in Denmark are caused by smoking.
Conclusion
Even if all known major risk factors identified to be at work in Denmark in 2022 were to be removed with the wave of a magic wand, there would be no decrease in the number of newly diagnosed cases of breast cancer and CRC in 2050, while new prostate cancers would be up by 25% vs the figure in 2021.
This effect is “unavoidable” and traceable to the increasing number of elderly people in the population that overwhelms the impact of cancer prevention.
“Increase in life expectancy and age will entail an increase in cancer incidence, despite maximum effect of preventive actions in the population.” Survival rates are increasing among cancer patients, many of whom live to develop one or more other types of cancer.
This is the conclusion of a recent study on cancers related to smoking or drinking, where secondary cancers are more likely in the same population.
This will mean much rethinking of options to ensure that cancer patients are catered for in all future health plans, even as preventive strategies are also applied.
Investment in early detection and targeted screening are called for in this situation to help manage the higher prevalence of cancers in the aging population.
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