An early form of breast cancer that affects only the cells inside the milk ducts warrants at least three decades of close monitoring after treatment due to persistent higher-than-expected long-term risks, a large study published on Wednesday in The BMJ found.
Ductal carcinoma in situ (DCIS), sometimes called Stage 0 breast cancer, is most often detected on screening mammograms. Whether aggressive treatment is warranted has been controversial, because not all cases of DCIS will eventually invade surrounding tissues.
Sometimes, DCIS is diagnosed outside of screening programs, when women find a palpable lump. For this study, UK researchers tracked 27,543 such women who were diagnosed between 1990 and 2018.
Annually, 13 of every 1,000 developed invasive breast cancer – more than four times the number expected among women in the general population, according to the report.
Each year, 3 per 1,000 died of breast cancer, almost four times the expected number, the report said.
Higher than average risks for invasive breast cancer and death from breast cancer persisted for at least 25 years after a DCIS diagnosis prompted by the discovery of a lump, they found.
The same research team had previously reported that rates of invasive breast cancer and breast cancer death in women with screen-detected DCIS are more than double those of women in the general population and remain raised for at least 20 years after diagnosis.
In the new study, mastectomy did not lower the risk of breast cancer death compared with breast-conserving therapy, likely because of cancers that developed in the opposite breast, an editorial published with the study noted.
A 2023 study found that among nearly 13,000 women treated for DCIS at more than 1,300 hospitals across the United States, only 52% consistently went for annual mammograms afterward.
