Cases of advanced breast cancer among women younger than 40 have tripled in the U.S. over the last three decades, a trend that researchers said has “been increasing at a steady or even accelerating rate.”
Advanced breast cancer in women ages 25 to 39 rose to 2.9 cases for every 100,000 women in 2009 from 1.53 per 100,000 in 1976, a small though statistically significant increase, according to a study published in the Journal of the American Medical Association. Applying the findings to the U.S. population showed that more than 800 cases of advanced breast cancer occurred in this age group in 2009 from 250 in 1976.
“This study identifies a trend that hasn’t been described in the past,” said Rebecca Johnson, medical director of the Adolescent and Young Adult oncology program at Seattle Children’s Hospital and the study’s lead author. “We’ll definitely need future studies to figure out why this change is occurring.”
The analysis found the percentage of advanced cases increased annually and at a faster rate toward the end of the study, researchers said. The rise was independent of race and ethnicity. There was no corresponding increase among older women, the study found.
Breast cancer is the most common cancer in 15- to 39-year-old females in the U.S. and accounts for 14 percent of all cancer in women and men in this age group, the authors wrote. Those diagnosed with the disease at a younger age have a higher risk of dying than those who are older. The national five-year survival rate for 20- to 34-year-olds diagnosed with advanced breast cancer is 31 percent, compared with 87 percent for women with less aggressive forms of the disease, researchers said.
“It’s a real phenomenon and an important one,” said Len Lichtenfeld, deputy chief medical officer for the Atlanta-based American Cancer Society. “Why it’s happening, we don’t know. We have identified that this is happening and it’s consistent over time and it’s a source of concern that we have to keep evaluating.”
The researchers looked at data from the U.S. National Cancer Institute’s Surveillance, Epidemiology and End Results registries from 1973-2009, 1992-2009 and 2000-2009 to determine if the breast cancer rate in young women was rising. The findings show that only advanced cancers, those that have spread beyond the breast to other organs, are rising and mostly among 25-to 34-year-olds, Johnson said in a telephone interview.
A separate analysis, not included in the paper, showed that while the number of advanced breast cancers is rising, the younger women with the disease are living longer than those diagnosed in the mid-1970s. Death rates haven’t risen as treatments improved, Johnson said.
Until more studies are done, Johnson said she could only speculate on the reason behind the increase. She said it could be “toxic environmental exposure or changes in lifestyle over the past 34 years.” The obesity epidemic though cannot fully explain the rise as being overweight early in life is actually protective against early onset breast cancer, she said.
Lichtenfeld, of the cancer society, said some of the increase may be explained by the fact that women now delay having children more than women 30 years ago. Having children early in life is protective against the disease, he said.
Still, the findings don’t mean that more younger women need to be screened for the disease with mammograms, Johnson and Lichtenfeld said. Screening targets finding cancer at its earliest stages.
“I don’t think that screening mammography practices should change based on our findings,” said Johnson, a breast cancer survivor herself who was diagnosed with the disease at age 27. “We would advocate for awareness in younger women. In women who get breast cancer before they start mammograms, most find the tumors themselves.”
If young women and their doctors act quickly to diagnose breast cancer when women have breast lumps or other symptoms, perhaps some of these cases of metastatic cancers can be picked up earlier, she said.
The U.S. Preventive Services Task Force, an independent medical advisory group to the government, in 2009 recommended against routine mammograms for women ages 40 to 49 who aren’t at an increased risk for breast cancer, while suggesting a mammogram once every two years for those 50 to 74. The American Cancer Society suggests annual mammograms starting at 40.
Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York, said she has treated many younger women for breast cancer and hasn’t noticed an increase over the past 12 years she has been practicing. She called the findings “upsetting.”
She said doctors and women need to take any breast lumps seriously no matter the patient’s age.
“If you have a breast mass you need to bring it to medical attention sooner rather than later,” Bernik said in a telephone interview. “The goal is to find things as soon as possible so we can start treatment as soon as possible. We need to put more effort into finding a way to best treat young women with breast cancer.”