By Marilynn Larkin
NEW YORK (Reuters Health) - Survivors of the 12 most common cancers are at higher risk for a wide range of diseases that require hospitalization and should be monitored for new illnesses during follow-up visits, researchers say.
"The population of long-term cancer survivors is growing worldwide due to advances in early detection and cancer treatment," Dr. Trille Kristina Kjaer of the Danish Cancer Society Research Center in Copenhagen told Reuters Health. "This growing cancer survivor population requires a complete understanding of additional illness risk in order to enable proper planning for care and support."
"The key point of this article is that cancer survivors may be affected by a broad range of somatic symptoms and disorders - this is most pronounced in the first years after primary treatment but remains an issue for years beyond normal follow-up," she said by email. "As with most diseases, early detection and management is key to ensure optimal outcome for the survivor."
Dr. Kjaer and colleagues studied data for 458,646 survivors of the 12 most frequent primary cancers listed in the Danish Cancer Registry between 1997 and 2014, and 2,121,567 matched cancer-free controls. The mean age was 69.
A cohort of cancer survivors was formed for each combination of cancer type and diagnostic group, with a corresponding group of cancer-free individuals, resulting in 132 unique cohorts.
As reported online March 7 in JAMA Oncology, more cancer survivors had comorbid conditions at the time of cancer diagnosis or study entry (Charlson Comorbidity Index of 1 or higher, 19%, vs. 13% of controls).
The risk of hospitalizations for somatic diseases was significantly higher for cancer survivors in almost all diagnostic groups - for example, breast cancer survivors were at higher risk for diseases in the nervous system (hazard ratio, 1.20); lung cancer survivors, for diseases in the respiratory system (HR, 5.85); and prostate cancer survivors, for diseases in blood and blood-forming organs (HR, 2.60).
Further, compared with controls, survivors of lung cancer also had a higher risk of leukemia (risk difference, 11.92) and non-Hodgkin lymphoma (RD, 8.94). Survivors of leukemia had a higher risk of infections and parasitic diseases (RD, 10.12), as did survivors of non-Hodgkin lymphoma (RD, 7.49). Survivors of brain cancer had a higher risk of nervous system diseases (RD, 12.43), and a higher risk of digestive system diseases was found in survivors of colon (RD, 9.75), rectum (RD, 12.95) and pancreatic cancer (RD, 9.97).
"Our findings have implications for how cancer survivors are followed-up both within specialized cancer follow-up but also over the long-term within general practice," Dr. Kjaer said. "I would expect similar findings both in terms of specific disease risk and time relations in the U.S. and other Western countries that provide state-of-the-art cancer treatment."
"Given different follow-up systems in different health care systems, it is important to ensure that health professionals across specialties are aware of these long-term risks," she noted. "Primary care physicians may have limited knowledge about late adverse effects of specific cancer treatments and of how to manage these. It is important that patients are made aware that they should be observant of symptoms they may develop and are instructed in what to do if they experience a symptom."
Dr. Tessa Faye Flores, Director of Cancer Survivorship and Screening at Roswell Park Comprehensive Cancer Center in Buffalo, New York, commented in an email to Reuters Health, "We're seeing more attention to survivorship and the long-term needs and concerns of those who've been treated for cancer, but still relatively few dedicated programs nationally. I do think cancer centers and care providers have to keep getting better at outreach to make sure people don't fall through the cracks once active treatment ends."
"Our program focuses on survivors as a whole as opposed to their primary oncologic process," she noted. "We discuss possible long-term complications of their treatment and provide recommendations to their primary doctors on monitoring for these possible complications. We screen for cardiotoxicity and toxicity since many chemotherapies have these a consequence of treatment."
"We also offer many support services (and) stress the importance of maintaining cancer screening, relationship with their primary care provider, and lifestyle modifications to decrease the risk of cancers," she said.
"We ask if survivors were hospitalized in the interim, and it's a mixed bag," she added. "It's usually related to other comorbidities such as coronary artery disease or chronic obstructive pulmonary disease."
JAMA Oncol 2019.