Johnson decided to do a national study. It’s published this week in the Journal of the American Medical Association.
It found that metastatic breast cancer — disease that spread to the bones or other organs — tripled in incidence among women younger than 40 between 1976 and 2009. These are women whose cancer had already spread by the time it was diagnosed.
The study just shows what many have suspected — the incidence of breast cancer in young women is increasing. It does not say why, although Dr. Len Lichtenfeld of the American Cancer Society did speculate.
[O]ne 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, levels of which soar during pregnancy.
“There is some thinking on our part that this is related to perhaps delay in childbirth or to the actual effects of pregnancy itself in this age group,” he says. “That may have something to do with the hormonal relationship.”
Lichtenfeld says another possible cause is toxic chemicals in the environment. Or possibly increasing obesity — though obesity in adolescents and young women may actually protect against breast cancer.
Something I want to point out about reporting of this story. NPR said that these are women whose cancer had already spread by the time it was diagnosed. Reading the JAMA article, I’m not sure that’s true.
Since 1976, there has been a steady increase in the incidence of distant disease breast cancer in 25- to 39-year-old women, from 1.53 per 100,000 in 1976 to 2.90 per 100,000 in 2009.
It doesn’t say that the initial diagnosis was metastatic breast cancer (mbc), at least by my reading.
EDIT: According to Jody (in the comments), this was a study of those who were initially diagnosed with mbc, so I stand corrected. However, that just leads me to wanting more information, like about how many women diagnosed with early stage cancer went on to develop metastatic disease?
Only that these women had mbc, or distant disease breast cancer as they call it here. Why split hairs? Because many in the cancer advocacy world fight against the ubiquitous perception that breast cancer caught early is curable. That was the common wisdom behind the campaign for early detection. The reality is much more complicated, as Dr. Susan Love explains.
Some of them are so “good” that they will never metastasize (spread throughout the body). And that means it doesn’t matter when you find them. They just don’t have the ability to cause someone to die of breast cancer. Others are very “bad” and so aggressive that no matter when you find them—which means even if you find them when they are still very small—they have already begun to wreak havoc. These are the types of cancers that cause women to die of this disease. Still others, probably about 30 percent, have the potential to become “bad” if not stopped early.
Still, this false perception, or perhaps incomplete perception, perpetuates. I understand why – we want to believe that cancer is predictable and that we can control it if we do it all according to the textbook. The reality is unsettling.
In an indirect way, I feel that NPR’s reporting of this story undermines the truth of breast cancer by subtly reinforcing this idea that the cancer is caught late. Sometimes when a cancer is diagnosed, it has already metastasized. But sometimes, a women is diagnosed with an early stage breast cancer, does everything “right,” and it still returns as metastatic breast cancer.
Additionally, this article makes no mention of mortality at all. If you didn’t know better, you might think that metastatic breast cancer is curable. As the JAMA article points out, “[t]he most recent national 5-year survival for distant disease for 25- to 39-year-old women is only 31 percent according to SEER data.” The flip side of that statistic, virtually ALL breast cancer deaths are from metastatic breast cancer.
I know it’s hard to get all that information in a short news story, but as this makes its rounds in the media outlet, let’s keep in mind what is not being said.
(1) We don’t know why this is happening.
(2) We don’t know which breast cancers will metastasize and which won’t.
(3) Very little research is done on metastatic breast cancer, despite it’s deadly nature.
(4) While this rise is concerning, in real numbers it’s pretty rare. Don’t panic.