Thyroid cancer is usually discovered in patients when doctors are performing CT scans, MRIS, or ultrasounds for unrelated reasons. Nodules are often find by men while shaving and women discover them while applying makeup. 90 percent of thyroid nodules are benign, but if you find a large lump in the front of your neck, doctors advise you to "pay attention to how it acts." Hoarseness in your voice may also be a sign that there is a cancerous thyroid nodule damaging your voicebox. If you're experiencing a chronic, mysterious cough with no fever or phlegm this could signify a larger problem. And lastly, if you have trouble breathing or swallowing this is a symptom of the cancer becoming highly aggressive and malignant.