Sebelius issued her statement following a government panel's recommendation on Monday, that said most women don't need mammograms in their 40s and should get one every two years starting at 50.
That recommendation was a break with the American Cancer Society's long-standing position that women should get screening mammograms starting at age 40.
The task force does "not set federal policy and they don't determine what services are covered by the federal government," Sebelius said.
Medicare, which covers older Americans and some younger ones who are disabled, provides women on Medicare coverage for an annual mammogram at age 40 and older.
Sebelius noted that there has been debate about the age at which routine mammograms should begin, and how often they should be given.
"The task force has presented some new evidence for consideration but our policies remain unchanged," she said. "Indeed, I would be very surprised if any private insurance company changed its mammography coverage decisions as a result of this action."
"My message to women is simple. Mammograms have always been an important lifesaving tool in the fight against breast cancer and they still are today. Keep doing what you have been doing for years - talk to your doctor about your individual history, ask questions and make the decision that is right for you," Sebelius said.
In the meantime, she added, it is clear that more research is needed into ways to help women prevent and fight breast cancer.
The recommendations from the task force have left women across the country confused about which advice to take. It also quickly led to charges from opponents of changing health care policy that it is an example of what could be expected from government-managed care.
In its report the panel of doctors and scientists concluded that such early and frequent screenings often lead to false alarms and unneeded biopsies, without substantially improving women's odds of survival.
But their recommendation was loudly criticized by breast cancer survivors who were diagnosed at a young age.