Various STAGES of CANCER

We actually cannot stage cancers as such as various cancers have different pathogenesis or mode of development. Some grow very rapidly while some take many years & moreover growth may get arrested at any stage. It has also been seen that rarely cancers may revert back spontaneously. 

In broad sense if we have to study various stages of cancers development, we can stage them as follows:-

Metaplasia:- This stage may be absent in many cancers such as most f blood cancers but in epithelial cancers such as cervical cancer, its frequently seen. It refers to change of a mature epithelium into another. Epithelium refers to lining cell of any cavity/ skin/ organ. There are various kinds of epithelium for different organs according to function they are supposed to perform. When epithelium changes, its ability to perform its function is impaired and moreover it may be hazardous or injurious.

Next comes stage of DYSPLASIA:- as we know word DYS refers to something abnormal. So is dysplasia refers to abnormal epithelium i.e. Epithelium gets poorly arranged. Various changes seen microscopically are increase in number of layers of cells, changes in epithelial attachment etc. Dysplasia can further be classified into mild, moderate and severe according to size, extent of tissue involvement, microscopic changes etc.

Next is the stage K/A carcinoma in situ:-  Sometimes it may be used interchangeably with dysplasia as its progression of dysplasia only. Carcinoma in situ means it is restricted to epithelium only and has not crossed its boundaries.

Last is the stage of overt carcinoma :- Once carcinogen in situ crosses epithelial boundaries, it starts spreading it becomes overt carcinoma. Usually tumor first invades the local structures n start growing there, it increase in size. At this time usually clinical manifestations start occuring but these may occur sooner or later. These are mostly either due to impaired function of affected organ or due to pressure symptoms i.e. When it grows in size, it puts pressure on surrounding organs disturbing their function also.

Stage of carcinoma can be further categorized on basis of spread. This is different for various cancers. We have various systems of staging such as TNM Staging, very commonly used. AJCC  staging mostly used for cancers of genital tract.

Last and most aggressive of spread of cancer is that of METASTASIS.

Metastatis refers to distant spread of tumor cells.

Example, cancer stomach spreading to bone or lung or any other organ. Various cancers have different tendency to metastatize. There are various theories regarding metastasis. Most commonly cells follow one of these two pathways- HEMATOGENOUS- via blood stream. Tumor cells enter blood vessel supplying tissue if origin, then enter circulation and settle in any other suitable organ. In this way a small cancer can spread to multiple organs. Following a similar fashion, cell may spread through LYMPHATICS. Various cancers have different tendency, regarding which pathway they prefer.