Serum carotenoids and uric acid levels in relation to cancer.

We studied the levels of serum total carotenoids and uric acid in newly diagnosed cancer cases. The levels of carotenoids and uric acid in serum samples from 94 subjects with cancer affecting different sites (21 breast, 26 head and neck, 13 lung, 17 genitourinary and 17 other sites) were compared with those of 92 controls who were matched for age, sex, Quetelet index and smoking history. Mean (+/- SE) levels of carotenoids were significantly lower among the cases than the controls (51.41 +/- 3.32 vs. 102.75 +/- 4.52 micrograms/dl, P < 0.001), when all the different sites were considered together. The mean (+/- SE) uric acid levels among cases and controls were 5.14 +/- 0.16 mg/dl and 4.21 +/- 0.18 mg/dl (P < 0.001), respectively. It was of interest that patients with genitourinary cancer had the lowest serum carotenoids levels, and the highest levels were found in patients with breast cancer. These results are informative but do not establish a causal link. There was no apparent association between serum urate levels and cancer site. The data presented here do not provide support for the protective antioxidant properties of uric acid in cancer.