This article is more than 5 years old. Information may no longer be current.
Metformin attenuates radioactive iodine induced blood cell reduction in differentiated thyroid cancer
In patients with differentiated thyroid cancer, the use of metformin appeared to mitigate hematopoietic toxicity induced by radioactive iodine-131 treatment, according to recent findings.
Kenneth D. Burman, MD, of MedStar Washington Hospital Center, and colleagues evaluated 40 patients with differentiated thyroid cancer (DTC) and confirmed diabetes who underwent treatment with radioactive iodine-131 between January 2000 and December 2013. Eligible participants also had a baseline pretreatment complete blood count, a minimum of one available complete blood count at follow-up, and were concomitantly treated with metformin during and for at least 3 months before treatment with iodine-131. These patients were compared to a control group of 39 patients with DTC who were not treated with metformin.
Kenneth D. Burman
Researchers assessed white blood cell count, absolute neutrophil count, absolute lymphocyte count, platelet count, hemoglobin and red blood cell count at baseline and at 1, 6 and 12 months after treatment.
The researchers found that in the control group, white blood-cell count showed reductions from baseline of 35.8% at 1 month, 21.8% at 6 months and 19.4% at 12 months after iodine-131 treatment (P < .0001 for all). The metformin group demonstrated a 17.1% decrease in white blood cell count from baseline to 1 month post-radioiodine-131 (P < .0001) and an 8.6% decrease at 6 months (P = .01); there was a slight increase at 12 months (0.2%). A comparison of these changes between the two groups revealed highly statistically significant differences at all time points (P < .001 at 1 month; P = .0027 at 6 months; P < .0001 at 12 months).
Metformin also appeared to have a considerable effect on absolute neutrophil count. At 1 month, the decrease in absolute neutrophil count in the control group was 35% (P < .001) vs. 6.1% in the metformin group. At 6 months, the reduction was 17% (P < .0001) in the control group vs. 1.3% in the metformin group. At 12 months, there was a 16% reduction (P < .0001) in the control group whereas the metformin group showed at 5.6% increase.
In the analysis of absolute lymphocyte count, the difference between the control and metformin groups was significant only at 6 months (P = .029), although it approached statistical significance at 12 months (P = .069).
“It has been demonstrated that metformin attenuated hematopoietic toxicity caused by [iodine-131 treatment] in patients with differentiated thyroid cancer,” the researchers wrote. “The data highlight that metformin has the potential to be used as a novel radioprotective agent for the bone marrow. However, larger-scale prospective studies are needed in order to elucidate the mechanism that is responsible for the radioprotective properties of metformin, to verify these results in other forms of therapeutic radiation, and to examine whether metformin’s radioprotective properties extend to other tissues besides the hematopoietic system.” – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.