Paris (France) (AFP) – Every year in France, more than 3,000 women under the age of 40 learn that they have breast cancer, the most common and deadliest among women. At this age, what are the particularities of this disease? What are its social and professional consequences?

Published on: 03/10/2026 - 09:54 Modified on: 03/10/2026 - 10:28

What specifics?

Of more than 61,000 new cases of breast cancer diagnosed each year in France, around 5% concern women under 40, according to the Institut Curie.

These cancers are generally more aggressive, and young age constitutes a less favorable prognosis factor, for several reasons.

Organized screening targets 50-74 year olds, but breast cancers in young women are "often discovered at a more advanced stage, with larger tumor sizes and more frequent lymph node invasion", points out Curie.

They are also more frequently affected by triple negative breast cancer (22% compared to 11% in the general population), which is more difficult to treat.

And among women under 40, the proportion of cancers linked to genetic predispositions is higher (15% compared to 5 to 7%).

“The announcement of breast cancer and its treatments is a tsunami for these young women,” underlines Florence Coussy, medical gynecologist and oncologist at Curie. Nearly three in four young women receive chemotherapy, compared to around one in three after the age of 60.

What impact on fertility?

“A pregnancy is possible after breast cancer,” assures Dr. Coussy, but “at a distance from treatment.”

A pregnancy plan can be considered "around 18 months after the end of treatments" for localized cancer. But "the higher the risk, the more we will ask for a small delay, so go to two years, sometimes three", specifies Elie Rassy, ​​oncologist at Gustave Roussy.

Also possible: “take a break from hormone therapy to allow for pregnancy, and resume afterwards, without impacting the prognosis of these young women,” notes the Curie specialist.

And added: “Breast cancer treatments do not cause infertility”: “the majority of pregnancies after breast cancer are spontaneous pregnancies”.

To preserve the chances of a post-cancer pregnancy, freezing of eggs or embryos can be offered.

What impact on professional life?

“Major side effects, including symptoms similar to those of menopause, difficulties in maintaining a professional life in parallel with long and heavy care,” observes the Institut Curie.

Overall, 20% of people with cancer suffer from professional disintegration, mainly within two years following the end of treatment.

“A feeling of mental fog” due to treatments, “for someone who is in the middle of university studies or starting a career, it is very limiting,” notes Dr. Rassy.

The constraints are also important "for a young mother who lives alone or is not well supported": "She has to take days +off+ from work to go for her treatments. And who will take care of her little ones when she is sick?".

If the patient receives chemotherapy and radiotherapy, heavy treatments requiring travel, this involves approximately 6-7 months of treatment.

An increasing incidence?

The incidence level of early-onset breast cancer increased continuously in France between 1990 and 2023, by an annual average of 1.5% among women aged 30 and by 0.9% among women aged 40, according to a study in October 2025.

Same trend by age subgroups: constantly increasing rates among 30-34 year olds and 35-40 year olds.

“Changes in hormonal factors may not be sufficient to explain this increase,” the study observed. Genetic or epigenetic factors, as well as the influence of environmental factors, could also influence this.

Towards earlier detection?

In France, the High Authority for Health (HAS) is currently evaluating the advisability of lowering the age of organized screening from 50 to 45 years and extending it to women aged 75 to 79.

The idea of ​​screening based on individual risk is also gaining ground, as suggested by the Court of Auditors.

An international clinical study (MyPeBS for My Personal Breast Screening), funded by the European Union and carried out in six countries (Belgium, Spain, France, Israel, Italy, United Kingdom), aims to evaluate the effectiveness and feasibility of personalized screening in women aged 40 to 70. Results expected at the end of 2027.

© 2026 AFP

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