A cancer patient’s ordeal doesn’t end with an all-clear from the oncologist. In fact, even if they’re sent home with the wonderful news that they’re cancer free, cancer survivors are likely to face long-term health issues. Especially if they opted for conventional cancer treatments.
Many of these health issues may be well-known to you, but another recent health issue has emerged. I’m talking about how cancer affects the way you age as well as what you can do about it.
There are 17 million cancer survivors in the U.S.; a number that’s expected to grow to 22 million by 2030.
This is welcome news of course, but survival often comes with a hefty price tag. Those who accept chemotherapy, radiation, drugs, or hormones may suffer from long-term health complications from these treatments.
These health consequences were highlighted by Mayo Clinic researchers in a review entitled, “Biology of premature aging in survivors of cancer”, which was published in 2017.
The Mayo team began their review by looking at the effects of conventional cancer treatment on children.
Most Children Develop Chronic Health Problems
By the age of 50 almost half of children, adolescents and young adults who survived Hodgkin’s lymphoma experienced at least one severe cardiovascular condition due to the cardio-toxic nature of the treatment.
In fact, survivors of childhood cancer are up to six times more likely than their age-matched peers to develop a secondary cancer.
They are also more likely to develop chronic health conditions, premature frailty, neurocognitive dysfunction, and poorer overall health. The prevalence of at least one chronic condition among children who have survived cancer for five years or more ranges from 66 percent (ages 5-19) to 88 percent (ages 40-49).
Summing up the evidence of their study of survivors of childhood cancer and their subsequent health issues the Mayo Clinic researchers write, “cancer therapies may accelerate the biology of aging.”
Turning to adults, their literature review uncovered many aging-related illnesses that occur prematurely.
A Series of Health Woes
Radiotherapy can lead to attention deficit disorder, memory loss, dementia, hardening of the arteries and leukemia.
Depending on the drug used, chemotherapy can give rise to attention deficit disorder, dementia, hearing loss, high blood pressure, cardiomyopathy, congestive heart failure, pulmonary fibrosis, liver disease, chronic kidney disease, hypothyroidism, chronic constipation, arthritis, and early menopause.
Hormone therapies can lead to cataracts, arthritis, and decreased bone mineral density. Long-term corticosteroid treatment can induce cataracts, weakened limbs, osteoporosis, thinning of the skin, infection, and impaired wound healing.
For targeted cancer-killing drug therapies the conditions that can result include hypertension, hypothyroidism, cardiomyopathy, and congestive heart failure. After identifying all these health problems, the researchers report, “We have demonstrated with clinical data that cancer survivors develop the health-related manifestations of aging more quickly than their peers. While aging prematurely is a better alternative to dying prematurely, a better understanding of what drives this process presents an opportunity for improvement.”
How Cancer Influences Mechanisms of Aging
To seek a better understanding of how cancer affects the aging process, the researchers looked at mechanisms of normal cellular aging that are hastened by cancer therapies.
The processes they examined include:
- Telomere attrition: Telomeres are structures that protect the ends of chromosomes and prevent important DNA from being lost during cell division. Maintaining the length of telomeres is seen as one of the keys to good health and aging, yet many cancer therapies shorten them. There’s also a direct relationship between shorter length and the risk for developing cancer in the first place.
- Cellular senescence: Aging humans have an increased burden of senescent cells. These cells secrete a cocktail of toxins that poison surrounding healthy cells, cause chronic inflammation, compromise organ function, and promote tumors. Most cancer therapies accelerate senescence.
- Stem cell exhaustion: Stem cells repair dysfunctional, injured, and diseased cells, and grow new tissue, but become exhausted particularly after the age of 65. When this occurs, people become vulnerable to the diseases of aging. Anthracyclines (doxorubicin, daunorubicin), used in the treatment of many cancers, cause stem cell exhaustion.
- Epigenetic alterations: Epigenetics refers to control mechanisms that alter the expression of genes. Many epigenetic modifications occur during normal cellular aging and the ones that accumulate over time can be used as a measure of how quickly a person is aging. Radiotherapy, chemotherapy, and other agents used in cancer treatments accelerate epigenetic aging. The researchers also noted that “the same epigenetic alterations that are targeted by some anticancer drugs are likely involved in the development of new secondary cancers.”
Other effects of cancer treatment that accelerate aging are DNA damage, changes to DNA repair genes, and free radical generation, all of which can promote secondary malignancies.
Senior Mayo Clinic researcher, Dr. Shahrukh Hashmi, believes their review picks up and emphasizes an important need.
How Survivors Can Help Themselves
“We are now beginning to see the gravity of a multitude of complications among cancer survivors. There is an essential and immediate need for formal cancer survivorship programs to prevent complications in millions of cancer survivors.”
He suggests survivors help themselves by adopting healthier lifestyles such as quitting smoking, limiting alcohol consumption, eating right, and exercising regularly. “Taking these steps will help reduce the chances of new cancer development and the development of heart disease,” he said.
Asked to comment on the expert review, Dr. Charles Shapiro, director of cancer survivorship programs at the Tisch Cancer Institute at Mount Sinai, in New York City, said, “We’re now struggling with our own success. This only comes up as a product of how well we’re doing in terms of cancer mortality and increasing the population of survivors. Now we have to deal with the consequences. Sure, you’re alive and that’s great, but there are consequences.”
He also said ongoing studies and clinical trials are evaluating the effect of limiting the amount of treatment needed so these aging effects can be reduced or eliminated.
Recently, researchers from the National Cancer Institute carried out their own study on survivors to look at their physical status. It was published in the Journal of the American Geriatrics Society in August.
Their findings accentuate the urgent need to deal with this issue.
Physical Decline Speeds Up
For their study the NCI researchers examined 1,728 men and women aged between 22 and 100. Of these, 359 had a history of cancer. They were tested for grip strength, walking pace and other tests of physical performance.
After the participants’ age, gender, body mass index, race, smoking status, education, and number of comorbid conditions were accounted for, they found that compared to those without cancer, survivors were more likely to experience physical declines due to accelerated aging.
In fact, they were 42 percent more likely to display a weaker grip strength. Those over the age of 65 were 61 percent more likely to have a slowed walking pace. Older survivors also scored lower on additional tests of physical performance.
The NCI researchers concluded by writing, “Cancer survivors, especially older individuals, demonstrate greater odds of and accelerated functional decline, suggesting that cancer and/or its treatment may alter aging trajectories.”
Future Help For Cancer Patients
An editorial in the same August issue of the Journal of the American Geriatrics Society welcomed the research writing “how cancer and its treatment impact aging has received little attention” and as survivors are growing, “focus on treatment-induced accelerated aging has become even more imperative.”
The researchers believe that the most promising method to reduce the problem is via senolytic agents – drugs that reduce cellular senescence. But in the meantime, they, like Dr. Hashmi, suggest lifestyle interventions such as diet and exercise as an area of focus “to prevent late complications and improve the health and well-being of cancer survivors.”
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