Cancer, the Second Largest Cause of Human Mortality
After cardiovascular disease, cancer is the second most prevalent cause of death in our species. One of the most important parts of a future toolkit of diverse rejuvenation therapies is a robustly effective, low-cost universal cancer therapy, one that can be applied to near all cancers with little need for customization. The best approach to that end is likely some form of interference in telomere lengthening. Unlike other known differences in cancer cells, this is plausibly the one aspect of cancer biochemistry that is both vital and immune to mutational change. A cancer can evolve its way out from under many forms of treatment, but not one that blocks the means by which cells remain able to replicate. Without a way to lengthen telomeres, cells die after a given number of replications, even cancer cells.
As noted in today's open access paper, overall cancer incidence is rising as the number of older people increases. This is an expected consequence of success in raising life expectancy; cancer is an age-related disease. As the immune system declines in effectiveness and forms of damage spread in the body, there is an ever greater chance of cells suffering a combination of mutations and circumstances that leads to cancer. Meanwhile, the individual risk of cancer is declining and odds of survival following a cancer diagnosis are increasing, a consequence of both public health measures and improvements in medical technology.
Mutation and cancer are core features of the biochemistry of multicellular life. Evolution needs mutation, and stem cells require the ability to replicate without limit. Some species are much more resilient to cancer than ours, but cancer will never be entirely eliminated as a possibility given the way in which our biology functions. For so long as the ability for cells to replicate exists, there will be failures of regulation that allow that replication to run amok. Thus it will always be important to have a cost-effective, highly reliable universal cancer therapy. That such a thing does not yet exist imposes a vast cost in suffering, lives, and funds expended on medical treatment.
The results of this systematic analysis demonstrate the substantial and growing global burden of cancer, with patterns of burden differing by sociodemographic index (SDI) quintile. In 2019, cancer-related disability-adjusted life years (DALYs) were second only to cardiovascular diseases in their contribution to global disease burden, and in the high SDI quintile, cancer overtook cardiovascular disease to become the leading cause of DALYs. Between 2010 and 2019, the number of new global cancer cases and deaths increased by 26.3% and 20.9%, respectively. However, the largest percentage increases in cancer incidence and mortality during the last decade occurred in the lower SDI quintiles, likely reflecting ongoing epidemiologic transitions, demographic shifts, and disparities in cancer prevention, care, and control.
While the absolute burden of cancer grew from 2010 to 2019, global age-standardized incidence rates remained similar at -1.1% and mortality rates decreased by -5.9%. These age-standardized mortality results suggest cautious optimism that some progress may have been made in early diagnosis and cancer treatment globally during the last decade.
However, inequities in the distribution and growth of cancer burden around the world diminish this potential advancement and suggest that an acceleration of efforts to effectively address cancer burden are needed. Of particular concern, recent progress in reducing age-standardized incidence and mortality rates seems concentrated in higher SDI locations, while both rates are still trending upward in lower SDI locations. The increasing age-standardized incidence and mortality rates in lower SDI quintiles may reflect several factors, including shifting population age structures, increasing capacity for diagnosis and registration of cancer cases and deaths, and changes in cancer risk factors, such as metabolic, behavioral, environmental, and occupational exposures.