The number of young women presenting with metastatic breast cancer has been slowly but steadily rising over the past 3 decades, a national study found.
The incidence of advanced breast disease among women ages 25 to 39 crept upward by 2.1% per year from 1976 to 2009 (P<0.001), reported Rebecca Johnson, MD, of Seattle Children's Hospital and the University of Washington in Seattle, and colleagues.
However, the same trend wasn't seen among older women in the analysis of the Surveillance, Epidemiology, and End Results (SEER) database, appearing in the Feb. 27 issue of the Journal of the American Medical Association.
These findings are worrying for 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 group pointed out.
Why more young women would be presenting with tumors that have already spread to bone, brain, lungs, or other distant sites isn't clear, they noted.
Rising obesity rates, changes in alcohol and tobacco use, and genetics are possible causes, commented Thomas Julian, MD, director of surgical oncology at Allegheny General Hospital in Pittsburgh.
Whatever the cause, something needs to be done to find these women at an earlier stage of cancer, he told MedPage Today in an interview.
"That's a problem because we don't usually screen before age 40 unless you know there are genetics in the family or a strong family history," he said.
The analysis of three SEER registries spanning 1973-2009, 1992-2009, and 2000-2009 showed an increase from 1.53 to 2.90 per 100,000 in incidence of breast cancer with remote metastases beyond the lymph nodes or adjacent organs among women, ages 25 to 39, over that time period.
That age group didn't appear to have a turning point for the rise in metastatic cancer incidence, but the trend appeared to be accelerating.
The steepest uptick occurred in the most recent era from 2000-2009, during which incidence rose 3.6% per year.
As another point of evidence, metastatic presentation rose as a proportion of all invasive breast cancer in the 25 to 39 age group, from 4.4% in the 1970s to 7.2% after the turn of the century.
Moreover, "there is no evidence for stage migration from regional, localized, or in situ categories, none of which had a decline in incidence at any time since 1976," the researchers noted.
The trends were seen among all races and ethnicities and urban and non-urban areas alike, although the increase appeared to have been more in the estrogen receptor-positive subtypes than estrogen receptor-negative disease (annual percent change 8.2 to 8.9 versus -0.5 to 5.4).
Women ages 40 and older showed progressively smaller increases in metastatic presentation by age group, without any significant trends in any group 55 years or older except for an increase in localized disease associated with the start of screening mammography programs during the 1980s.
Part of the study funding came from a Seattle Children's Guild Association grant.