(NBC) -- It wasn't until women started having routine mammograms that Doctors were able to spot it: A type of breast cancer called Ductal Carcinoma in SITU, often called stage zero breast cancer.
"It's a precancer, or the last step before invasive cancer develops," said M.D. Oncologist Banu Arun of The University of Texas MD Anderson Cancer Center.
Patients usually undergo a Lumpectomy to get rid of the cancerous tissue, and then Doctors depend on the tumor size, a woman's menopause status and other factors to determine if she needs radiation to kill any remaining Cancer cells.
A test called Oncotype DX goes deeper, giving Doctors invaluable information about the tumor itself.
Using the tissue taken during the Lumpectomy, Doctors analyze the tumor's genes and plug that information into a mathematical model that gives women a score.
"This gene array test was able to identify low versus high risk individuals, and this score successfully identified these individuals," said Dr. Arun.
Oncotype DX has been used in women with more advanced stages of Cancer for seven years.
Since then the test became available the use of Chemotherapy in women has dropped twenty percent.
Dr. Arun hopes for similar results in women with Ductal Carcinoma in SITU.
"It will really discriminate between whether radiation is indicated or not," said Dr. Arun.
Sparing some women the side effects of potentially unnecessary treatment.
The test is not approved by the FDA, but experts say, very few gene tests have the agency's approval. They expect the test to hit the market by the end of the month.