More women are now undergoing early tests that reveal pre-cancerous breast tissue.
Early diagnosis can save lives but in reality, few of those lesions go on to become tumours - and doctors have no good way of predicting which ones will.
As a result, many women have to undergo surgery who might never develop the disease!
All that may change soon.
Researchers from the Wyss Institute of Biologically Inspired Engineering at Harvard University have discovered a new breast-cancer therapy that partially reverses the cancerous state in cultured breast tumour cells and prevents cancer development in mice.
This could pave the way to treat early stages of the disease without resorting to surgery, chemotherapy or radiation, said a new study published in the journal Science Translational Medicine.
"The findings open up the possibility of someday treating patients who have a genetic propensity for cancer, which could change people's lives and alleviate great anxiety," said Don Ingber, founding director, Wyss Institute.
Amy Brock, a former Wyss Institute post-doctoral fellow, grew healthy mouse or human mammary-gland cells in a nutrient-rich, tissue-friendly gel.
Healthy cells ensconced in the gel formed hollow spheres of cells akin to a normal milk duct. But cancerous cells, in contrast, packed together into solid, tumour-like spheres.
Brock treated these cancerous cells with a short piece of RNA called a small interfering RNA (siRNA) that blocks only the HoxA1 gene, said the study.
The cells reversed their march to malignancy, stopping their runaway growth and forming hollow balls as healthy cells do. What's more, they specialised as if they were growing in healthy tissue.
The siRNA treatment also stopped breast cancer in a line of mice genetically engineered to have a gene that causes all of them to develop cancer.
"There was no aha moment. But after enough evidence builds up, you turn to each other and say this is really doing something here," Brock added.