By Carolina Lima | Published October 6th, 2025 | 3 min read
#BreastCancerAwareness
#PinkOctober #OncologyUpdates
Breast
cancer is the most frequently diagnosed cancer among women worldwide and its
prevention remains a global health priority. While genetic
predisposition—particularly BRCA1 and BRCA2 mutations— often dominates public
discourse, recent evidence suggests that lifestyle factors significantly
influence risk, even in genetically susceptible individuals. This article
summarizes findings from Zhang et al. (2024), published in the Journal
of the National Cancer Institute (JNCI), which evaluated the combined
impact of genetic risk and lifestyle behaviours on early-onset breast cancer.
Study
Overview
Zhang
et
al. conducted a large prospective cohort study including over 10,000 women to
evaluate how genetic risk and lifestyle factors jointly influence breast cancer
incidence.
The genetic
risk was quantified using a polygenic risk score (PRS) based on multiple
susceptibility loci. Participants were stratified into low, intermediate,
and high genetic risk categories.
Lifestyle
was assessed using a
composite score based on five modifiable factors:
- Poids corporel sain (IMC)
- Activité physique régulière
- Consommation limitée d’alcool
- Non-tabagisme
- Alimentation équilibrée
Women were
classified as having a favourable, intermediate, or unfavourable
lifestyle profile. The primary outcome was the incidence of diagnosis of breast
cancer before age 50.
Key
Findings
- Genetic Risk Matters, but It’s Not Deterministic
Women in
the highest genetic risk category had a significantly elevated risk of
early-onset breast cancer compared to those in the lowest category. However,
genetics alone did not fully explain the variation in risk.
- Lifestyle Has a Strong Independent Effect
Across all
genetic risk groups, women with a favourable lifestyle had a substantially
lower risk of developing breast cancer than those with an unfavourable
lifestyle. Among women at high genetic risk, adopting healthy behaviours
reduced the relative risk by nearly 40%.
- Combined Impact Is Powerful
The lowest
risk was observed in women with both low genetic risk and favourable lifestyle,
while the highest risk occurred in those with high genetic risk and unfavourable
lifestyle. Importantly, even women with high genetic susceptibility
benefited from lifestyle improvements.
Clinical
Implications
The study
by Zhang et al. reinforces a critical message: genetic risk does not negate
the benefits of lifestyle interventions. While genetic testing remains essential
for identifying high-risk individuals, prevention strategies should not stop
there.
Healthcare
professionals should reinforce the importance of empowering women toward better
lifestyle choices — maintaining a
healthy weight, exercising regularly, limiting alcohol, avoiding smoking, and
following a balanced diet. These simple actions can significantly reduce breast
cancer risk, even in women with strong genetic predispositions.
Final
Thought
It may be
time to
shift the conversation from what women
cannot change to what they
can.
Breast cancer prevention is not only about genetic testing and imaging—it is
built on
everyday lifestyle decisions. By empowering patients with practical,
evidence-based guidance, clinicians can play a pivotal role in
reducing the
global incidence of breast cancer.
Read next: Transforming lifestyle habits during chemotherapy: Insights from the LEANer trial
About
the Author – Carolina Lima
Carolina is a specialist in Anaesthesiology with a deep passion for learning and sharing medical knowledge. Dedicated to advancing the field, Dr. Lima strives to bring fresh, evidence-based insights to the medical community. Viewing medicine not merely as a profession but as a lifelong journey of continuous learning, Dr. Lima is committed to making complex information clear, practical, and useful for healthcare professionals around the world.
