<s>[INST] I was first diagnosed with 1 nodule on half of my thyroid (I had left side removed /tumor in thyroid had to remove to do biopsy in 1989) then it became 2 and now 4. Three are solid and 1 with fluid. Had biopsy done early in April of this year and they were benign. My question and concern is can they eventually become cancer if they are not taken care of? [/INST] Benign nodules of the thyroid if left untreated can become malignant over a long period of time. Roughly 10% nodules become malignant over 20 years. The features of they're turning malignant are sudden increase in size, pain, appearance of other nodules outside the thyroid, change in voice, difficulty in breathing or swallowing. Any of these changes should prompt you to consider removal of the remaining thyroid. </s>