People who have had cancer age faster than those who haven't lived with the disease, according to a study.
Writing in the online journal ESMO Open, experts called for more research to be done to reduce the accelerated ageing process, lengthen lifespan and improve the quality of their lives.
Thanks to more effective diagnosis and treatment, the number of cancer survivors is set to rise. Currently there are 30 million around the globe, but by 2025, around 19 million new diagnoses will be made every year and most of these will produce long term survivors, the researchers said.
Why do people with cancer naturally age faster?
Researchers said cancer survivors are more likely to develop long-term conditions, and sooner than the rest of the general population.
They hypothesised that this is most likely due to the damage caused by chemotherapy and radiotherapy to normal healthy tissues.
These types of treatment can diminish 'physiological reserve'- the capacity in organs and biological body systems given to us at birth - and the body's natural resilience to overcome internal and external biological stressors
"While ageing prematurely is a better alternative to dying prematurely, a better understanding of what drives this process presents an opportunity for improvement," said researchers.
They trawled databases for published evidence on the cellular processes involved in ageing and the potential impact of cancer treatments on these and found a wide range of side effects and late complications, which have implications not only for the individuals concerned, but also for health services.
The key findings of the study were:
:: Childhood cancer survivors are between three and six times as likely to develop a second cancer.
:: Childhood cancer survivors' estimated life expectancy is 30% lower than that of the general population.
:: The risk of frailty among bone marrow transplant recipients is around eight times as high as that of their siblings.
:: Long term steroid treatment, a component of many cancer treatment strategies, is associated with a higher risk of cataracts, osteoporosis, nerve damage, skin thinning, infection and impaired wound healing.
:: Cancer treatment is associated with various aspects of biological ageing.
:: Certain primary cancer drugs are associated with hearing loss, reduced thyroid gland activity, high blood pressure, congestive heart failure, muscular weakness, arthritis, kidney and liver diseases, chronic constipation, and infertility.
:: Radiotherapy is associated with dementia, memory loss, carotid artery hardening, and secondary bone marrow cell and blood cancers.
:: Tamoxifen (adjuvant treatment to stave off the return of cancer) is associated with cataracts.
A need for future research
The researchers said that despite these undesirable side effects, cancer treatments are worthwhile for scores of patients with the disease, and that ageing is 'part of life'.
But accelerated ageing, experienced by many cancer survivors as a direct consequence of their treatment is something that can, and should be, minimised. For one thing, cancer survivors deserve it, and for another, it's a public health issue, they said.
"We believe that cancer survivors deserve long-term follow up for the mitigation of the late effects," they concluded.
"Future research to better understand mechanisms of accelerated ageing-like phenotypes is essential for the oncology community as well as from a public health and health policy perspective.
"The ultimate goal of these studies will be to prevent late complications using early interventions, including lifestyle changes and medications."
In response, Dr Aine McCarthy, from Cancer Research UK, told HuffPost UK: "The results of this study highlight that while more people are surviving cancer than ever before, we have to do more to ensure cancer survivors have a good quality of life. A big part of this will be carrying out more research to develop kinder treatments that still work, but have fewer short and long-term side effects."
Macmillan's specialist advisor for treatment and recovery, Dany Bell, told HuffPost UK: "This research reflects just how much the story of cancer has changed in this country. A cancer diagnosis is now a moment that is frequently not life-ending, but nearly always life-changing.
"Earlier diagnosis and more effective cancer treatment means that more people are living for longer after a cancer diagnosis. Whilst this is welcome, surviving does not always mean living well, with thousands of people living with long-term side effects of treatment that can have a profound effect on the body.
"These findings hammer home that whilst survival rates are important, they aren't the only measure of success. An important part of cancer care should be for patients to be able to discuss with their doctor how their cancer experience might affect their quality of life in the longer term. People must also have access to a personalised package of care and support from the point of diagnosis so they are able to have as good a quality of life as possible, for as long as possible."