Young women are increasingly affected by breast cancer, according to a French study. Over the past three decades, the increase in breast cancer among young women has been constant. Every year, without interruption since the 1990s, the incidence of breast cancer increases by 1 to 2%.
Breast cancer: you can be affected from the age of 30
The study was carried out using the cancer registries of the Francim network, in collaboration with Public Health France (SPF), the National Cancer Institute (INCa) and the French Society of Predictive and Personalized Medicine (SFMPP). It was presented on October 8 at the 11th congress of the SFMPP and was published simultaneously in the international journal The Breast.
Between 1990 and 2023, 229,352 cases of breast cancer were recorded in France. The incidence of these early cancers has increased continuously over this period:
- +63% in women aged 30 (increasing from 15.1 to 26.3 cases per 100,000 person-years);
- +33% in women aged 40 (rising from 98.7 to 131.2 cases per 100,000 person-years).
These results confirm data from other international studies. In the United States, for example, an annual increase of 1.4% in the incidence of breast cancer in women under 50 was observed between 2012 and 2021. In the United Kingdom, the incidence increased by 22% in women aged 25 to 49 between 1993-1995 and 2016-2018.
Overall, the incidence of breast cancer is increasing in all Western countries. But this increase among young women is particularly worrying in France: young age, less than 40 years old, is in itself a poor prognosis factor, independently of other parameters such as the size of the tumor or lymph node invasion.
Why are more and more young women discovering breast cancer before the age of 35?
Although the causes of this progression are not clearly identified, the role of environmental and hormonal factors is strongly suspected. Professor Pascal Pujol, president of the French Society for Predictive and Personalized Medicine (SFMPP) and first author of this study, explains:
“This observation raises two questions: that of the cause and that of the age of screening. Concerning the probable cause, organized screening cannot be held responsible for this increase since it does not concern young women. Environmental and hormonal factors are therefore in the foreground.”
According to a recent American study, it is hormone-dependent cancers (expressing estrogen receptors) that are increasing the most. Hormonal factors are therefore the first to be suspected:
- Decrease in age at puberty;
- Increase in age at first pregnancy;
- Decline in the number of children;
- Decrease in breastfeeding;
- Increased use of oral contraceptives.
These developments follow a trajectory parallel to that of the incidence of breast cancer. “Nevertheless, these hormonal factors do not appear to be sufficient to explain the sharp increase in breast cancer”specifies Professor Pujol. “Other lifestyle changes probably play a role: dietary habits, exposure to pollutants and radiation, sedentary lifestyle, stress, etc. Certain pollutants, called endocrine disruptors, particularly those from the plastic and PVC industry, have chemical activities close to estrogens (“estrogen-like effects”).
Worrying increase in breast cancer among young women: should we review screening in France?
Faced with this worrying situation, several avenues are mentioned. Such as better preventing obesity, a sedentary lifestyle and “junk food”, as well as reducing exposure to pollutants.
But given the increasingly younger age of affected women, the professor especially recommends lowering the age of breast cancer screening. As is also done in the United States, where the American Cancer Society has recommended a mammogram every two years from the age of 40 since 2024.
While waiting for such a development in France, Professor Pujol underlines the importance of personalizing screening according to risk factors, particularly familial ones. And to investigate any breast mass in a young woman:
“If benign tumors (fibroadenomas) are the most common in these age groups, mammography is not always effective due to breast density. An ultrasound and/or MRI is often useful to complete the diagnosis. MRI is the test of choice in case of doubt. Because its sensitivity is significantly better than that of mammography or ultrasound.”
The increase in breast cancer among young women is a warning signal, but also an opportunity: to rethink our relationship with health, prevention and the environment. Understand to act, before it is too late.