Cancer metastasis--a multistep process

Dermatologists are confronted daily with proliferative growths which can reach considerable size, but mean no danger to the patient. Seborrheic keratoses are one example. Other growths, such as basal cell carcinoma, are locally destructive. Normally, however, we do not hesitate to reassure the patient about the benignity of the tumor once excised. The malignancy of squamous cell carcinomas and melanoma, however, is undoubted. Thus, excessive proliferation and even local invasiveness are not sufficient to define malignancy. It is the life-threatening aspect of metastasis that physicians are mostly concerned about.