🎗️ Early Warning Signs of Stage 0 Cancer: Recognising Carcinoma In Situ in Mouth, Skin, Breast & More Cancer doesn’t always begin with visible symptoms — it often starts quietly at Stage 0, known as Carcinoma in Situ (CIS). At this stage, abnormal cells are still confined to their place of origin and haven’t spread — making early detection highly curable. Here are common early warning signs to look out for: 👄 Mouth: Persistent white or red patch, sore that doesn’t heal. 🩷 Breast: Small lump,