Question: difference between carcinoma in situ and invasive carcinoma

title: Carcinoma in situ
text: Carcinoma in situ ( CIS ) , also known as in situ neoplasm , is a group of abnormal cells . While they are a form of neoplasm there is disagreement over whether CIS should be classified as cancer . This controversy also depends on the exact CIS in question ( i.e. cervical , skin , breast ) . Some authors do not classify them as cancer , however , recognizing that they can potentially become cancer . Others classify certain types as a non-invasive form of cancer . The term `` pre-cancer '' has also been used .