RENEE MONTAGNE, HOST:
More young women are being diagnosed with advanced breast cancer. It's a newly recognized trend. The numbers are small, but it's been going on for a generation; and researchers say it's been accelerating in recent years. NPR's Richard Knox has this report on the findings, which appear in the current "Journal of the American Medical Association."
RICHARD KNOX, BYLINE: The discovery that breast cancer incidence is rising among women under 40 had unusual origins. It was in a Houston book group about seven years ago. Turns out three of the women in the group were diagnosed with breast cancer, and Alison Henning was one of them.
ALISON HENNING: The fact that I know two other people in my circle of friends who've been diagnosed with breast cancer under 40, is amazing. I mean, it's just - it's ridiculous, to me, in an otherwise very healthy population.
KNOX: One of the other women was Dr. Rebecca Johnson, who was diagnosed at the age of 27. She's now a pediatric cancer specialist at Seattle Children's Hospital. She kept in touch with Alison Henning after she moved to Seattle, and she wondered about the bigger picture.
DR. REBECCA JOHNSON: Sort of the going wisdom was that breast cancer is uncommon in young women, compared to older women. But I wondered how common it actually was.
KNOX: So Johnson decided to do a national study of breast cancer incidence in young women - the one that's published this week. It found that metastatic breast cancer - disease that's spread to the bones or other organs - tripled in incidence among women under 40, since 1976. These are women whose cancer had already spread by the time it was diagnosed. But the actual numbers of women are small. About 800 women under 40 are being diagnosed with advanced cancer nowadays, compared to 250 back then. By comparison, 212,000 U.S. women of all ages get breast cancer every year.
The research has uncovered other troubling things. Incidence has gone up fastest in younger women, 25 to 34. It affects women of all ethnic backgrounds, and it's been accelerating in recent years. I asked Johnson what she thinks all this means.
JOHNSON: Well, it suggests to us that the trend is real. And it certainly suggests to us that the acceleration is happening at an exponential rate. It tells us nothing about why the increase is occurring, of course.
KNOX: Dr. Len Lichtenfeld, of the American Cancer Society, says one thing that famously distinguishes women of this generation is that they've been delaying childbirth. And most of the cancer increase involves tumors that are sensitive to the hormone estrogen.
DR. LEN LICHTENFELD: There is some thinking, on our part, that this is related to perhaps delay in childbirth; or the actual effects of pregnancy itself, in this age group, that may have something to do with the hormonal relationship.
KNOX: Another possible cause is toxic chemicals in the environment or possibly, increasing obesity, although obesity in adolescents and young women may actually protect against breast cancer. Lichtenfeld says women shouldn't over-react to these findings
LICHTENFELD: When people hear about research like this, they tend to become far more concerned than the numbers reflect. These are very small numbers.
KNOX: But he says scientists should, and will, investigate what's going on.
LICHTENFELD: When we see trends that continue to increase over time, we have to be concerned.
KNOX: And Alison Henning, the Houston woman who helped inspire the new study, says young women should pay attention, too.
HENNING: If you think that something's wrong or feels funny, follow through yourself. Don't allow your doctors to dismiss it just based on your age.
KNOX: You have to be your own advocate, she says. Richard Knox, NPR News
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