NEPHROTIC SYNDROME INCREASE CANCER RISK

NEW YORK (Reuters Health) - People with nephrotic syndrome are at increased risk of incident cancer within five years, new research from Denmark suggests, and such patients have a worse cancer prognosis than those without the disorder.

"We provide evidence linking nephrotic syndrome with cancer," the authors write. "The association was most pronounced for specific cancers, including lung cancer, kidney cancer, lymphoma, and multiple myeloma."

"Our study underscores that occult cancer, in particular lung cancer and multiple myeloma, should be considered in patients hospitalized with nephrotic syndrome. The risk of cancer may not be high enough to justify a regular screening program, but we suggest targeted clinical workups based on symptoms and clinical suspicion of specific cancer," lead author Dr. Christian F. Christiansen of Aarhus University Hospital in Denmark wrote in an email to Reuters Health.

Using Danish national registries, Dr. Christiansen and his colleagues conducted a population-based cohort study of all individuals diagnosed with nephrotic syndrome between 1980 and 2010 without a preceding cancer history.

Of 4293 individuals with nephrotic syndrome, 338 developed cancer over a median follow-up of 5.7 years. The 5-year risk of any cancer was 4.7% in patients who had nephrotic syndrome, a 73% increased risk compared with the general population. The association was strongest for lung cancer, kidney cancer, lymphoma, and multiple myeloma. It was highest within one year of nephrotic syndrome diagnosis (standardized incidence ratio=4.49), and it remained increased beyond one year (SIR=1.34).

The 5-year mortality after cancer was 68.5% in cancer patients who had nephrotic syndrome and 63.4% in cancer patients without the disorder (adjusted hazard ratio=1.20), according to findings online May 13 in The American Journal of Medicine.

Dr. Bradley Carthon of Winship Cancer Institute of Emory University School of Medicine in Atlanta, Georgia, told Reuters Health by email, "Most of what has been known about this prior to now has been based on case reports and smaller studies. This is one of the largest population-based cohort studies to try to accurately assess the association between nephrotic syndrome and future cases of all cancers. It reconfirms the prior case reports and series that show association with nephrotic syndrome and various cancer diagnoses. It also highlights the different rates of association that are higher with certain cancers than others."

"These findings are somewhat surprising," said Dr. Carthon, who was not involved in the study. "Prior small studies assessed the risk of cancer with certain glomerular disorders. This was the first study to look at all the associated glomerular disorders encompassed within the diagnosis of nephrotic syndrome."

As to whether these findings should change how patients with nephrotic syndrome are managed, he said, "While very intriguing, the data are a bit early to change management for all patients diagnosed with nephrotic syndrome. Further studies and analyses will help determine if different screening procedures need to be implemented in these patients, particularly for the disorders with the highest rate of association, such as multiple myeloma and Hodgkin's lymphoma."

The authors also call for more research and say limitations of the current study may include possible database coding errors and lifestyle and behavioral factors associated with long-term cancer risk that they did not capture.

However, they write, this study, based on data from the entire Danish population and containing complete follow-up for cancer and death, is essentially free from selection bias and losses to follow-up.

SOURCE: http://bit.ly/1kHFAm8

Am J Med 2014.