Trendspotting: Breast Cancer Mortality Rates are Rising Among Women Under 40

NEWSWIRE: 3/03/21

• After declining for decades, breast cancer death rates are no longer falling among U.S. women under age 40. Researchers attribute the increase to “rapidly rising” rates of Stage 4 diagnoses among women in their 20s and 30s. (Radiology)
• NH: Between 1989 and 2017, breast cancer mortality rates in the U.S. fell 40%. This has been attributed to improved treatment and increased screening rates starting in the 1980s. The death rate declined rapidly (between -1.5% and -3.4% per year) for all age brackets among adult women between age 20 and 79.
• According to new research, this decline continues among women age 40 and older. But it has ceased among younger women. Since 2010, the breast cancer mortality rate has risen +2.8% per year among women in their 20s and +0.3% per year among women in their 30s. (Thus we're talking about women born in the 1980s and 1990s, aka Millennials.) One contributing factor is a significant rise in Stage 4 breast cancer in younger women, especially white women. From 1976 to 2015, the distant-stage (metastatic) breast cancer rate among 25- to 39-year-olds jumped 151%. From 2009 to 2015 alone, it rose 32%.
• As seen below, this increase can be observed in a rising metastatic incidence rate (blue and green dots) over at least the last 20 years and in a rising mortality rate (red dots) over the last 10 years. 

• Breast cancer cases and deaths are still much more likely (roughly 10X) to occur in women over 40, as shown in the charts below. Among women ages 20 to 39, the mortality rate is roughly 3 per 100,000 women. Among women ages 40 to 69, it’s around 30 per 100,000.  

• Why is this increase happening? Regular mammograms are not typically recommended for women under 50, so younger women are more likely to have cancer that goes undetected. Less clear is why younger women are seeing more later-stage diagnoses in the first place.
• This reversal could be part of a troubling pattern that we first reported on a couple of years ago. The incidence rates of several different types of cancer, including colorectal and pancreatic cancer, were found to be rising faster or falling slower among Americans under 50 than those over age 50. That was thought to be linked to increasing obesity rates. (See “Millennials at Higher Risk for Obesity-Related Cancers” and “Colorectal Cancer on the Rise.”)
• Breast cancer, though known to be linked with obesity, was not implicated in that study. But these researchers find that, indeed, the same younger-versus-older split is happening here. There has been a gradual rise (about +0.5% per year) in breast cancer incidence rates overall among women ages 20 to 39 since 2000, and an even more significant increase in distant-stage cases that is pushing up mortality rates.
• All of this underscores a broader point I’ve been making for several years now. The cessation of improvement in U.S. mortality rates and life expectancy is being driven by the non-elderly (see “Adults Under Age 65 Driving Decline in U.S. Life Expectancy”), and some of the most alarming developments we’re seeing are related to obesity in Millennials. The lead author of this study warns that, given the current trend, “in two to three years, the mortality rate will be increasing significantly in these women."