Breast cancer in young women has increased 29% since 1990, raising urgent questions about lifestyle, reproductive changes, and prevention in U.S. communities.
Something is changing in breast cancer: it remains the most common tumor among women, but risk profiles are not the same. This group of diseases continues to be closely linked to aging, and in fact, most diagnoses occur in women over 55; However, in recent decades, cases in premenopausal women have been increasing more rapidly. A study published this Monday in The Lancet Oncology reveals that, while the rate of new diagnoses in older women has not changed substantially in the last three decades, in women between 20 and 54 years old it has increased by 29% since 1990.
According to the research, which provides an overview of the breast cancer situation in more than 200 countries, 161 new cases per 100,000 women over 55 were diagnosed in 2023. This is three times higher than the number diagnosed among women aged 20 to 54 (50 new cases per 100,000). The interpretation is that age remains a key factor in the risk of developing breast cancer, but by broadening the focus and observing the trend of recent decades, scientists have discovered that diagnoses among younger women, while far fewer, are increasing at a faster rate.
The researchers don’t delve deeply into the causes of this shift, but for oncologists like Gemma Viñas, head of the Breast Cancer Unit at the Catalan Institute of Oncology in Girona, in northeastern Spain, the data aligns with what they observe in their practice: “The incidence is increasing in all age groups, but we are seeing a greater increase in young women.” Isabel Echavarria, scientific secretary of the Spanish Society of Medical Oncology, agrees: “There is evidence that the incidence is increasing in young women, and this is something that worries us oncologists.”
The reasons behind this phenomenon are, to a large extent, still a mystery. Viñas asserts that there is probably “an impact from changes in reproductive factors,” such as the earlier onset of menstruation or the delay in motherhood and the number of children (breastfeeding and pregnancies are protective factors). Other modifiable risk factors, linked to lifestyle, such as being overweight or alcohol consumption, may also be playing a role, she suggests. “In young patients, we don’t know the real cause. It’s probably the sum of many factors,” she hints.
This isn’t the first time science has observed a rise in cancer, a disease traditionally associated with aging, among young adults. According to a study published in the journal BMJ Oncology in 2023, tumors in people under 50 have increased by almost 80% in three decades. Colon cancer is the most paradigmatic, and the one where this emerging trend has been most studied, but it’s not limited to that: it has also been observed in endometrial, kidney, thyroid, and breast cancer, among others. The scientific community is intrigued and has yet to fully define the scope of the phenomenon—some studies find this trend in 13 tumors, others reduce it to half a dozen—but many experts attribute it to the rise in unhealthy lifestyle habits, such as smoking, a poor diet, and being sedentary.
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