Several women I have talked with recently have had multiple tumors, with one being invasive ductal carcinoma (IDC)—cancer that has invaded the cell wall—and another being ductal carcinoma in situ (DCIS)—cancer that remains inside the cell wall. Research published in the British Journal of Cancer (online, April 27, 2010) shows that, when both IDC and DCIS are present, the cancer tends to be less aggressive, with a five-year disease-free survival of 97.4 percent versus 96 percent for IDC alone.
The two were more likely to co-exist in younger, pre-menopausal women and in those whose cancers are hormone-positive.
Research was done on 1355 women. Researchers speculate that the co-existence of DCIS and IDC may mean a distinct type of less-aggressive cancer.
Source: Wong, H., Lau, S., Yau, T., Cheung, P. Epstein, R. J., ‘Presence of an in situ component is associated with reduced biological aggressiveness of size-matched invasive breast cancer’, British Journal of Cancer, vol. 102, no. 9, 1391-1396 (2010).