Understanding Papillary Thyroid Cancer Papillary thyroid cancer starts in the thyroid gland, a butterfly-shaped organ at the base of your neck. This gland produces hormones that regulate metabolism, heart rate, and body temperature. Papillary cancer develops from the follicular cells in the thyroid and tends to grow slowly. This cancer often appears as a small lump or nodule in the thyroid. Many people discover it during routine checkups or imaging tests done for other reason