Serum Iodine Levels and 8-Year Survival in Patients After Kidney Cancer Diagnosis

The aim of this study was to evaluate the association between serum iodine (I) levels and kidney cancer mortality. The role of serum iodine levels in relation to 8-year survival rates in survivors of kidney cancer has not previously been established. In this prospective study, we analyzed 284 consecutive, unselected survivors of kidney cancer and determined their 8-year survival in relation to iodine levels.

Micronutrient levels were measured using inductively coupled plasma mass spectrometry (ICP-MS). Each survivors of kidney cancer was assigned to one of four groups based on the quartile distribution of iodine levels, ranked in ascending order. The multivariable models included covariates such as age at diagnosis, sex, smoking status, type of surgery, histopathological classification and serum levels of selenium, zinc, copper and the zinc-to-copper ratio.

We observed that survivors of kidney cancer with serum iodine levels in quartiles III and IV had significantly higher all-cause mortality compared to those in quartile II (reference quartile) (HR = 2.83; p = 0.012; HR = 2.64; p = 0.017). Furthermore, multivariable analysis revealed a significant association between serum iodine levels (quartiles III and IV vs. quartile II) and mortality due to kidney cancer progression (HR = 4.17; p = 0.031; HR = 3.94; p = 0.038, respectively). This association was significant only among men in quartile IV (HR = 16.5; p = 0.027). Additionally a positive association was observed between iodine levels in quartile IV and all-cause mortality from non-kidney cancer-related deaths (HR = 5.41; p = 0.05).

To our knowledge, this study is the first investigation of relationship between serum iodine levels and survival of survivors of kidney cancer.