Breast cancer is the most frequently diagnosed cancer among women globally and remains the top cause of cancer-related death in women, according to the World Health Organization (WHO).
Tobacco use contributes to cancer risk due to harmful chemicals in cigarettes that can trigger abnormal cell growth. While smoking is not considered a direct cause of breast cancer, evidence suggests it may increase the likelihood of developing the disease in certain individuals.
The American Cancer Society reported that in 2021, an estimated 281,550 women in the United States would be diagnosed with breast cancer, with 43,600 expected to die from it. Globally, the WHO recorded 2.3 million new breast cancer diagnoses and 685,000 deaths in 2020.
Tobacco use remains widespread. According to the Centers for Disease Control and Prevention (CDC), roughly 50.6 million American adults—about 1 in 5—were current tobacco users as of 2019. On a global scale, over 80% of the 1.3 billion people who use tobacco reside in low- and middle-income countries, as noted by the WHO.
A 2017 study published in Breast Cancer Research revealed several findings about smoking and breast cancer risk:
- Women who had ever smoked were 14% more likely to develop breast cancer than those who had never smoked.
- Starting smoking before age 17 raised the risk by 24%, while beginning between ages 17 and 19 was associated with a 15% increase.
- Women who smoked for more than a decade faced a 21% greater risk; smoking for over 30 years elevated that risk slightly to 22%.
- Among those who had quit smoking, individuals who had stopped less than 10 years prior still had a 28% increased risk.
- Women with a family history of breast cancer faced the highest risk—56%—if they began smoking before turning 20.
The same study found that smoking was specifically associated with Luminal A breast cancer, a subtype that typically grows slowly and has a relatively favorable prognosis.
Nicotine, the substance in tobacco responsible for addiction, is not carcinogenic on its own. However, a 2021 study indicated that nicotine might promote the spread of breast cancer to the lungs.
Cannabis smoke, like tobacco smoke, contains many of the same harmful compounds. Although this has raised concerns, a 2019 meta-analysis found no conclusive link between cannabis smoking and breast cancer. Still, the researchers called for more extensive studies, as current data remains limited.
Passive smoke is composed of the smoke from burning tobacco and the smoke exhaled by smokers. The CDC reports that this type of smoke contains over 7,000 chemicals, with hundreds considered toxic and about 70 classified as carcinogenic.
Existing research suggests that smoking may elevate breast cancer risk, especially among women who started smoking young, smoked heavily, or began smoking before giving birth for the first time.
Since smoking is one of the few modifiable risk factors for breast cancer, health professionals strongly encourage prevention and cessation. Quitting smoking—or never starting—remains a key strategy for reducing cancer risk.