In Situ Phase

In situ, Latin for "in its place", the carcinoma in situ is the earliest, usually curable, stage of cancer. In the in-situ phase, a small colony of malignant cells develops, which have already settled in the tissue but do not yet show any invasive growth. This growth phase is very slow because there is no actual blood vessel system and the transport of nutrients and wastes takes place by diffusion through the surrounding tissue. Such in situ carcinomas are usually only a few millimetres in size and spread flat. The in-situ phase of a tumor can last for many years. Tumours at this stage are often referred to as precancerous tumours.