In a potentially ominous report, researchers have found "a small but statistically significant" increase in the incidence of advanced breast cancer in younger women in the United States.
“The trajectory of the incidence trend predicts that an increasing number of young women in the United States will present with metastatic breast cancer in an age group that already has the worst prognosis, no recommended routine screening practice, the least health insurance, and the most potential years of life,” the authors write a study appearing in the February 27 issue of JAMA.
"Young women with breast cancer tend to experience more aggressive disease than older women and have lower survival rates," the researchers noted.
The study was conducted by Rebecca H. Johnson, M.D., of Seattle Children's Hospital and University of Washington, Seattle, and colleagues, using data from three U.S. National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) registries.
“In the United States, breast cancer is the most common malignant tumor in adolescent and young adult women 15 to 39 years of age, accounting for 14 percent of all cancer in men and women in the age group. The individual average risk of a woman developing breast cancer in the United States was 1 in 173 by the age of 40 years when assessed in 2008," the article noted.
Younger not always better
The researchers also found that the rate of increasing incidence of distant disease -- meaning malignancies that had metastisized, or spread to other parts of the body -- was higher in younger women. The greatest increase occurred in 25- to 34-year-old women. Progressively smaller increases occurred in older women by five-year age intervals and no statistically significant incidence increase occurred in any group 55 years or older.
“For young women aged 25 to 39 years, the incidence of distant [metastisized] disease increased in all races/ethnicities assessed since at least 1992, when race/ethnicity became available in the SEER database,” the authors write. These increases occurred in both metropolitan and nonmetropolitan areas, and were statistically significant in African American and non-Hispanic white populations.
The researchers said the causes for the increase are not known but said more study is needed.
"If verified, the increase is particularly concerning, because young age itself is an independent adverse prognostic factor for breast cancer, and the lowest five-year breast cancer survival rates as a function of age have been reported for 20- to 34-year-old women.
"The most recent national 5-year survival for distant disease for 25- to 39-year-old women is only 31 percent according to SEER data, compared with a 5-year survival rate of 87 percent for women with locoregional breast cancer,” the authors write.