Invasive Breast Cancer Death Rates Are Falling

A new analysis has found that since 1988, breast cancer-specific mortality has fallen by nearly one-third.

Researchers at the US National Cancer Institute (NCI; Rockville, MD, USA) and Dongguk University (Seoul, Republic of Korea) conducted a study to estimate hazard ratios for breast cancer specific death from time of invasive breast cancer diagnosis using data from the NCI surveillance, epidemiology, and end result registries database from 1973–2010. The study included 543,171 women with first primary invasive breast cancer. They calculated the proportion of improvements in stage- and age-specific breast cancer survival in the United States—as explained by tumor size or estrogen receptor (ER) status—both with and without stratification.

The results showed that hazards from breast cancer specific death declined from 1973 to 2010, not only in the first five years after diagnosis, but also thereafter. Stratification by tumor size explained less than 17% of the improvements, except for women aged 70 years or older with local (49%) or regional (38%) disease. Additional adjustment for ER status (positive, negative, or unknown) from 1990-2010 did not explain much more of the improvement, except for women aged 70 years or older within five years after diagnosis. The study was published on July 20, 2015, in the Journal of Clinical Oncology.

“These results indicate that factors other than nonsurgical size or ER status accounted for most of the stage-specific survival improvements in women younger than age 70 years,” said corresponding author Mitchell Gail, MD, PhD. “For women 70 years of age and older, changes in nonsurgical size explained much of the improvement from 1973 to 1979 and 2005 to 2010 in the first five years. After five years, neither nonsurgical size alone nor nonsurgical size and ER status explained much improvement in women older than 70 years.”

Studies reveal that the proportion of women who underwent screening mammography increased from 29% in 1987 to approximately 70% from 2000 onward. Other studies indicate that 70% of women age 70 or older with invasive breast cancer received adjuvant hormonal therapy and/or chemotherapy in 2000; 78% of patients aged 50–69 years received such treatment; and for patients younger than 50 years of age, the percentage jumped to 88%.

ER status helps guide treatment for breast cancer. Breast cancers that have a large number of ER+ tumors can be treated with hormone therapies like tamoxifen and aromatase inhibitors, and tumors tend to be linked to better survival than ER- tumors. Overall, five-year survival is about 10% better for women with ER+ breast cancer than for those with ER- tumors. However, after five years, this survival difference begins to decrease and over time may even disappear.

Related Links:
US National Cancer Institute
Dongguk University