The incidence of many cancers increases with age.
I wonder if you have ever wondered why the older you are, the more likely you are to get cancer?
Medical research generally agrees that the body ages as we age. At this time, the microenvironment in the body provides a more suitable environment for the growth of cancer cells.
First, one of the hallmarks of aging is an increase in systemic mild chronic inflammation. This constant inflammation is not the same as our everyday inflammation. For example, the fingers become inflamed and swollen after being cut, and pathogenic bacteria enter the respiratory tract to cause respiratory inflammation, all of which belong to daily inflammation.
Everyday inflammation does not have long-term effects, while systemic mild chronic inflammation tends to be less severe than everyday inflammation, lasts longer, and alters the body’s microenvironment , have long-term effects on the body. Scientists believe that this persistent inflammation is closely related to the development of cancer cells and the progression of cancer.
(Source: soogif)
Secondly, as people age, their immune function declines, which is another contributing factor to cancer. At this time, the physical strength of the police (immune cells) that help the body fight against the disease becomes weak. When cancer cells invade, the police (immune cells) defending the human body cannot identify and remove cancer cells, so that the team of cancer cells continues to grow and eventually develop into cancer.
(Source: soogif)
In addition to increased chronic inflammation and decreased immune function, aging also causes many other changes in the body’s microenvironment, which are important factors in the development of cancer [1].
In general, with the influence of many factors directly or indirectly produced by human aging, the probability of normal cells becoming cancerous increases, the immune cells defending the human body decline, and the ability to remove cancer cells increases. Weaker, older adults are also more likely to develop cancer.
In other words, aging itself is one of the important risk factors for cancer.
The treatment of cancer may also have adverse effects on older patients.
Currently, approximately 50% of all cancers occur in patients over the age of 65, and this proportion is estimated to rise to 70% as human lifespans increase[2].
However, recruitment of older patients has been limited in clinical trials of various cancer therapies. According to the U.S. Food and Drug Administration (FDA), only 40% of patients over the age of 65 and less than 10% over the age of 75 are enrolled in cancer clinical trials [3].
(Source: soogif)
And the results of these clinical trials are implemented in the real clinic, and doctors administer the treatment at relevant standard doses, which may challenge the treatment of elderly patients.
Example:
Chemotherapy rapidly kills proliferating cancer cells and prolongs survival in older adults. However, due to the influence of the aging microenvironment, the elderly may become resistant to chemotherapy;
Targeted therapy can target genes more precisely than chemotherapy and radiotherapy, but it can still lead to drug resistance. Whether the resistance to targeted therapy is age-related, further research is needed to confirm [2].
Perhaps the proportion of older adults in cancer patients should be fully considered in future cancer clinical trials.
A recent study published in Nature found that metabolic changes that occur in the body as we age can create an environment conducive to the metastasis of cancer cells.
The specific explanation is that the metabolism of protein and fat in our body produces a by-product called methylmalonic acid (MMA). Methylmalonic acid gradually accumulates in a person’s blood with age. Scientists have found that the accumulation of methylmalonic acid in the body can cause a series of chain reactions that can give cancer cells the ability to metastasize and continue to progress.
This means that if older adults have cancer, the cancer will spread more easily.
(Source: Organ Story)
However, the researchers also suggested that since protein and fat metabolize methylmalonic acid, reducing excessive intake of protein and fat may enhance the body’s ability to fight cancer.
So, in older adults, a low-protein and low-fat diet may reduce the risk of cancer metastasis[4].
In conclusion, increasing age may contribute to the development and progression of cancer. Compared with young people, the elderly should pay more attention to cancer screening, early detection and early treatment, and the prognosis will be better.
Reviewer: Chen Yupei| Attending Physician, Doctor, Department of Radiotherapy, Sun Yat-sen University Cancer Center
References
[1]Fane M, Weeraratna AT. How the ageing microenvironment influences tumor progression.
Nat Rev Cancer. 2020 Feb;20(2):89-106. doi: 10.1038/s41568-019-0222-9.
[2]Daste A, Chakiba C, Domblides C, Gross-Goupil M, Quivy A, Ravaud A, Soubeyran P. Targeted therapy and elderly people: A review. Eur J Cancer. 2016 Dec;69:199-215. doi: 10.1016/j.ejca.2016.10.005. Epub 2016 Nov 15. PMID: 27855351.
[3]Singh H et al. FDA analysis of enrollment of older adults in clinical trials for cancer drug registration: a 10-year experience by the US Food and Drug Administration. J. Clin. Oncol. 35 (Suppl. 15), 10009 (2017).
[4]Gomes AP, Ilter D, Low V, et al. Age-induced accumulation of methylmalonic acid promotes tumor progression. Nature. 2020 Aug 19. doi: 10.1038/s41586-020- 2630-0.
*The content of this article is for the popularization of health knowledge and cannot be used as a specific diagnosis and treatment suggestion, nor can it replace the face-to-face consultation of a licensed physician, and is for reference only.
*The copyright of this article belongs to Tencent Medical Dictionary. Unauthorized reprinting by media is prohibited. Illegal reprinting will be investigated for legal responsibility according to law. Individuals are welcome to forward to the circle of friends.