A carcinoma in situ is the very early stage of a cancer when the abnormal cancer cells are confined to their original site. At this stage no tumour has grown and no cancer cells have spread. It may be that many cancers remain at this dormant stage for months, or even years, before they start to grow and spread into a proper cancer. This may be because the cells of the carcinoma in situ do not have the ability to stimulate new blood vessels (see above under ‘Local growth and damage to nearby tissues’ – angiogenesis). If they cannot stimulate new blood vessels to grow then the cancer itself cannot grow or spread
Treatment aims to cure the cancer in many cases. With modern medicines and therapies, many cancers can be cured, particularly if they are treated in the early stages of the disease. (Doctors tend to use the word remission rather than the word cured. Remission means there is no evidence of cancer following treatment. If you are in remission, you may be cured. However, in some cases a cancer returns months or years later. This is why doctors are sometimes reluctant to use the word cured.)Treatment may aim to control the cancer. If a cure is not realistic, with treatment it is often possible to limit the growth or spread of the cancer so that it progresses less rapidly. This may keep you free of symptoms for some time.