DCIS is a very early form of breast cancer. There are cancerous cells there, but they are all confined to the inside of the ducts (tubes) within the breast. As they have not broken through the wall of the breast ducts, there is no risk of the cancer having spread. This is why DCIS is sometimes called a 'pre-cancerous' condition.
In the past, DCIS has been treated with mastectomy (complete removal of the breast). Now, similarly to invasive breast cancer, it is thought that if only a small area of DCIS is found in the breast then it may be possible to remove just the lump with a small area (margin) of surrounding healthy tissue (lumpectomy or wide local excision). This is known as ‘conservative surgery’.
For both DCIS and invasive breast cancer whether a mastectomy may be necessary will depend on the following factors:
- how large the tumour is
- if more than one area of the breast is affected
- where the tumour is positioned in the breast.
With both DCIS and invasive breast if the area affected is very large, more than one area of the breast is affected or it is positioned behind the nipple then a mastectomy might still be the best option.
Because DCIS cannot spread, there generally isn’t any need to remove the lymph nodes. However, with invasive breast cancer there is a risk of the lymph nodes being affected, so either a sample of lymph nodes or all the lymph nodes will additionally be removed.
At this time if a lumpectomy or wide local excision is done, for both DCIS and invasive breast cancer, these are both likely to be followed by radiotherapy. Research studies are exploring whether certain types of DCIS may not need radiotherapy after conservative surgery.
Tamoxifen, which is a hormonal treatment, again may be given for both DCIS and invasive breast cancer (following surgery) if ‘oestrogen receptors’ are found on the surface on the breast cancer cells.
So the decision about the extent of surgery needed to be done for either DCIS or invasive breast cancer really depends on the individual situation.