Breast cancer cells. Coloured scanning electron micrograph (SEM) of a clump of breast cancer cells, showing their uneven surfaces and cytoplasmic projections. Clumps of cancerous (malignant) cells form tumours, which possess the ability to invade and destroy surrounding tissues and travel to distant parts of the body to seed secondary tumours. Malignant cells proliferate and grow in a chaotic manner, with defective cell division retained within each new generation of cells. Breast cancer is treatable if it is detected early. Surgical removal of the tumour followed by radio- or chemotherapy can effect a complete cure. Magnification unknown.