6. A Lump, Thickening, or New Mass
A new lump or swelling, particularly one that is painless and continues to grow, may be an early sign of cancer, such as lymphoma or skin cancer. Lumps in the breast, testicles, lymph node areas — neck, armpits, groin — or anywhere else on the body that persist beyond two weeks should be checked by a doctor.
Signs of breast cancer can include a lump in the breast, nipple changes, or changes to the skin such as redness or dimpling. Changes in the skin and tissue in the armpit can also be an early sign of breast cancer. The same American Cancer Society annual report estimates tens of thousands of new cases of breast ductal carcinoma in situ (DCIS — an early form of breast cancer confined to the milk ducts) in 2025 alone, underscoring why any breast change warrants professional evaluation.