Regression of papillary thyroid cancer using metformin: a case report

: Metformin is a medication that has been used for almost a century for the treatment of type II diabetes. Relatively recent studies have discovered metformin to have utility for the treatment and prevention of number malignancies. Metformin has demonstrated in population studies to reduce papillary thyroid cancer however, the specific effect of metformin on papillary thyroid cancer in humans has not been previously reported. Herein we present the first clinical evidence of anti-tumor effect of metformin on papillary thyroid cancer resulting in clinical regression. This was found in a 35-year-old female who noticed a lump in her neck and was found to have a thyroid nodule. On biopsy, her nodule was proven to be papillary thyroid carcinoma. The patient chose to take metformin in lieu of surgical removal of her thyroid. Repeated monitoring demonstrated clinical regression of her carcinoma, with the size of her nodule decreasing from 1.4×1.1×1.2 to 0.66×0.52×0.67 cm 3 , or an 88% reduction in volume. There was also no evidence of any progression to her lymph nodes. This opens a potentially new treatment modality for papillary thyroid cancer which traditionally has had the mainstay treatment options of surgery and radioactive iodine, however more work is needed to be done to confirm the generalizable results for this one case.