Seven warning signs of breast cancer: a new lump or thickening in the breast or armpit; change in breast size or shape; skin changes such as dimpling, puckering, redness, or scaliness; nipple changes (inversion, discharge, bleeding); persistent breast or nipple pain; swelling of part of the breast; a rash or crusting on the nipple/areola.

Mammography and ultrasound are first-line scans to detect suspicious breast changes; MRI is used for problem-solving or staging. However, imaging alone cannot confirm cancer. Definitive diagnosis requires tissue sampling—most commonly an image-guided core needle biopsy (stereotactic, ultrasound-guided, or MRI-guided) or, less commonly, an excisional biopsy—followed by pathological examination. Pathology determines cancer presence and subtype to guide treatment.

For routine screening, digital mammography—especially 3D tomosynthesis—is the best initial scan. Ultrasound is a useful adjunct for evaluating dense breasts and distinguishing cysts from solid masses. Breast MRI is the most sensitive test and is preferred for high‑risk women, problem solving, or staging. PET/CT is reserved for assessing suspected metastatic disease.

The first red flag of breast cancer is usually a new breast lump or thickening, often painless, that feels different from surrounding tissue. Changes in size, shape, persistent localized pain, skin dimpling, nipple inversion, or unusual discharge can also signal concern. Any new or unexplained breast change should prompt medical evaluation promptly.

Breast cancer begins when DNA mutations in breast cells cause uncontrolled growth, forming a tumour. Most originate in the milk ducts (ductal) or lobules (lobular). Mutated cells can invade surrounding tissue and spread. Risk increases with age, genetics, hormones, and lifestyle factors, though not all tumours have clear causes. Early signs include a new lump, nipple changes, discharge, or skin dimpling.

See a clinician if breast pain is focal, persistent, or linked to a new lump, nipple discharge (especially bloody), skin changes (dimpling, redness, ulceration), swollen axillary nodes, unexplained weight loss, or onset after trauma. Seek prompt care for severe pain, fever, spreading redness (possible infection/abscess), or if you’re over 40 or have a strong family history of breast cancer—evaluation rules out serious causes.