More U.S. women are surviving breast cancer than a generation ago.

Chalk it up to advances in screening and treatments since 1975, researchers report in The New England Journal of Medicine.

Which has been the bigger help — screening or new treatments? Scientists from seven different organizations tackled that question for the report.

They came up with different answers. Some showed that screening had been more important. Others sided with treatment.

Still, there was no mistaking the powerful impact those advances have had on saving lives.

Screening, Treatment Both Helped

Screening can flag breast cancer at an earlier, more survivable stage. But treatment is needed, too.

“While we didn’t agree with each other as to the percentages of benefit, all seven groups concluded that the decline in the rate of death from breast cancer is a combination of screening and therapy, and not restricted to one or the other,” says researcher Donald Berry, PhD, in a news release.

Berryworks at the University of Texas M.D. Anderson Cancer Center.

More Breast Cancer Survivors

For U.S. women, breast cancer is the No. 2 cause of cancer death. Lung cancer is women’s leading cause of cancer death.

Breast cancer is also women’s most common cancer, except for nonmelanoma skin cancers.

America’s breast cancer death rate has been dropping, even as more women have been diagnosed. In short, more women have, and survive, breast cancer than in the past.

Slightly more than 2 million living U.S. women have been treated for breast cancer, according to the American Cancer Society.

Breast Cancer Then and Now

Berry’s study paints a picture of breast cancer over the years. It shows many advances, though breast cancer hasn’t been defeated.

Consider these numbers from Berry’s study:

—Breast cancer killed 48 out of 100,000 women aged 30-79 in 1975.

—Breast cancer killed 38 out of 100,000 women aged 30-79 in 2000.

—Women’s breast cancer death rate dropped 24% from 1990 to 2000.

The study didn’t look at breast cancer in men. It also didn’t break down the death rate for different ethnic groups. Black women and women who are economically disadvantaged have been shown to be more likely to die of breast cancer than whites.

Advances in Treatment

Many treatments available to today’s breast cancer patients weren’t around in 1975.

Chemotherapy was virtually unheard of in 1975. Now, it’s commonplace.

“The percentage of women who received chemotherapy increased from essentially 0% in 1975 to about 80 percent in 2000,” write the researchers.

Tamoxifen is another example. It’s a drug that blocks the hormone estrogen from estrogen-sensitive breast tumors. It’s typically taken for five years after other treatments (such as surgery, chemotherapy, and radiation).

“The use of tamoxifen increased from essentially 0% in 1975 to about 50% in 2000,” write the researchers. They add that tamoxifen has mainly been used in patients with estrogen-sensitive tumors.

Other hormone-related drugs have also been developed, such as the new aromatase inhibitors, which cut estrogen production.

The Age of Mammography

Breast cancer screening “increased dramatically” from 1975 to 2000, the researchers write.

The number of women age 40 and older who reported getting mammograms annually, every other year, or at least irregularly rose from 1985 to 2000, the study shows.

Mammography uses X-rays to photograph breast tissue. Those images are checked for breast abnormalities, which may raise suspicions of cancer. Mammograms can help detect tumors at early stages that might be missed during a breast exam.

Mammography isn’t perfect. It may miss some tumors, sometimes needs follow-up tests, and does expose patients to some radiation. But it’s still widely recommended as a major screening tool and has helped save many lives.

Researchers continue to work on new ways to find and treat breast cancer. Their progress may further boost the ranks of breast cancer survivors.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Berry, D. The New England Journal of Medicine, Oct. 27, 2005; vol 353: pp 1784-1792. News release, University of Texas M.D. Anderson Cancer Center. American Cancer Society: “What Are the Key Statistics for Breast Cancer?” WebMD Medical News: “Fewer American Women Dying of Breast Cancer.” WebMD Medical News: “Breast Cancer: Explaining Ethnic Differences.”