Smoking raises levels of male-type hormones called androgens in women’s blood, which may help explain why smoking increases breast cancer risk. A study of 867 Italian women found that current smokers had about 13 percent higher testosterone and 14 percent higher androstenedione levels than never smokers, with the effect stronger in postmenopausal women who smoked more pack-years.
A new study of 867 women found that cigarette smoking is linked to higher levels of male hormones called androgens in the bloodstream. Researchers discovered that both current smokers before and after menopause had elevated testosterone and androstenedione compared to women who never smoked. The more pack-years a woman smoked, the higher her androstenedione levels climbed, especially after menopause. According to Gram Research analysis, this connection between smoking and these hormones may help explain why smoking increases breast cancer risk in women, offering scientists a new piece of the puzzle in understanding how smoking damages health.
Key Statistics
A 2026 cross-sectional study of 867 women from the EPIC Florence cohort found that current smokers had 13 percent higher testosterone levels compared to never smokers, regardless of menopausal status.
According to research reviewed by Gram, women who currently smoke showed 14 percent higher androstenedione levels than never smokers in both pre- and postmenopausal age groups.
A 2026 analysis of 867 Italian women revealed a dose-response relationship in postmenopausal smokers, where androstenedione levels increased predictably with lifetime smoking exposure measured in pack-years.
Research from the EPIC Florence cohort demonstrated that smoking’s association with elevated androgens remained significant even after adjusting for body weight, exercise, alcohol use, and diet.
The Quick Take
- What they studied: Whether smoking cigarettes changes the levels of male-type hormones (androgens) in women’s blood, and if this might explain why smoking increases breast cancer risk
- Who participated: 867 women from Italy who were part of a large health study called EPIC Florence, recruited between 1993 and 1998. The group included both women before menopause and after menopause, with different smoking histories
- Key finding: Women who currently smoke have about 13 percent higher testosterone and 14 percent higher androstenedione levels than women who never smoked. The effect was seen in both younger and older women, and the longer someone smoked, the higher their hormone levels climbed
- What it means for you: If you smoke, your body may be producing higher levels of hormones that could increase breast cancer risk. This research suggests one biological pathway through which smoking damages health. Quitting smoking could help normalize these hormone levels, though this study cannot prove causation
The Research Details
Researchers used a cross-sectional study design, which means they took a snapshot of 867 women at one point in time and compared their smoking habits to their hormone levels. The women were part of the EPIC Florence study, a large health research project that started in 1993. At enrollment, women answered detailed questions about their diet, lifestyle, exercise habits, alcohol use, and reproductive history. Scientists also measured their height, weight, and waist size. Blood samples were collected and frozen in liquid nitrogen for later testing.
To find the connection between smoking and hormones, researchers used statistical models that adjusted for many other factors that could affect hormone levels. These factors included age, body weight, waist size, education level, physical activity, alcohol consumption, calorie intake, and reproductive history. By adjusting for these factors, scientists could isolate the specific effect of smoking on androgen levels.
The researchers analyzed pre- and postmenopausal women separately because hormone levels change dramatically after menopause, and smoking might affect each group differently.
This research approach is important because it reveals a potential biological mechanism linking smoking to breast cancer. Rather than just showing that smokers get more breast cancer, this study identifies a specific hormonal change that could explain why. Understanding these mechanisms helps scientists develop better prevention strategies and helps doctors explain to patients exactly how smoking damages their health
This study has several strengths: it included a reasonably large sample size of 867 women, used stored blood samples for accurate hormone measurement, and adjusted for many confounding factors that could skew results. However, because it is cross-sectional, it shows association, not causation. The study cannot prove that smoking causes higher androgens, only that they occur together. Additionally, the study only included Italian women, so results may not apply equally to all populations. The researchers measured hormones at only one point in time, so they could not track how hormone levels changed over time with smoking
What the Results Show
Current smokers had significantly higher testosterone levels than never smokers in both age groups. In women before menopause, current smokers had testosterone levels about 13 percent higher (with a range of 1 to 26 percent higher). In women after menopause, the increase was also about 13 percent. The pattern was similar for androstenedione, another male-type hormone: current smokers had about 14 percent higher levels before menopause and 14 percent higher after menopause compared to never smokers.
A particularly important finding emerged for postmenopausal women: there was a clear dose-response relationship with androstenedione. This means that as women smoked more cigarettes over their lifetime (measured in pack-years), their androstenedione levels increased in a predictable way. The more someone had smoked, the higher their hormone levels tended to be. This dose-response pattern is considered strong evidence that smoking directly influences these hormones, rather than the relationship being coincidental.
The hormone changes were consistent across both age groups, suggesting that smoking affects androgens regardless of whether a woman is still menstruating or has gone through menopause. This consistency strengthens confidence in the findings.
The study did not report major secondary findings beyond the primary androgen measurements. However, the fact that the association held true after adjusting for many other factors (body weight, exercise, alcohol use, diet) suggests that smoking’s effect on androgens is independent of these lifestyle factors. This indicates that smoking itself, not just the lifestyle patterns of smokers, drives the hormone changes
Previous research has established that estrogen (a female hormone) plays a major role in breast cancer development. However, scientists have more recently recognized that androgens (male-type hormones) also matter for breast cancer risk. This study adds to growing evidence that androgens influence breast cancer development. The finding that smoking raises androgen levels provides a new explanation for why smoking increases breast cancer risk. Earlier studies showed smoking increases breast cancer risk, but the mechanism was unclear. This research suggests that altered hormone levels may be one important pathway
The study’s main limitation is its cross-sectional design, which captures only one moment in time. Researchers cannot determine whether smoking caused the higher androgens or whether women with naturally higher androgens are more likely to smoke. The study included only Italian women enrolled between 1993 and 1998, so findings may not apply to other populations or current smokers. Researchers measured hormones only once, so they could not track how levels changed with smoking duration or after quitting. The study did not measure other factors that might influence androgens, such as certain medications or medical conditions. Additionally, the study relied on self-reported smoking history, which can be subject to recall errors
The Bottom Line
If you smoke, this research provides additional motivation to quit. Quitting smoking may help normalize androgen levels and reduce one potential pathway to breast cancer risk. This evidence is moderately strong because the association was consistent across age groups and showed a dose-response pattern. However, this single study cannot prove that lowering androgens through smoking cessation will prevent breast cancer. Women concerned about breast cancer risk should discuss smoking cessation and breast cancer screening with their healthcare provider
This research is most relevant to women who smoke or have smoked, particularly those with family history of breast cancer or other breast cancer risk factors. Women considering smoking should understand this as one additional health risk. Healthcare providers should use this information when counseling patients about smoking cessation. Researchers studying breast cancer mechanisms should consider androgens as part of the picture. Women who have never smoked can take this as reassurance that they are avoiding this particular risk pathway
Hormone levels may begin to normalize within weeks to months after quitting smoking, though this study did not measure this directly. Breast cancer risk reduction typically takes years to become apparent after quitting smoking. Most research suggests that breast cancer risk decreases gradually over 10 to 20 years after quitting, though it never returns completely to the level of never smokers
Frequently Asked Questions
Does smoking increase hormone levels that cause breast cancer?
Smoking raises androgen hormone levels in women by about 13 to 14 percent. These hormones may increase breast cancer risk, though this study shows association, not definitive causation. Quitting smoking could help normalize these hormone levels
How much do androgens increase with smoking?
Current smokers had testosterone about 13 percent higher and androstenedione about 14 percent higher than never smokers. The longer someone smoked (measured in pack-years), the higher their androstenedione levels, especially after menopause
Can quitting smoking lower these hormone levels?
This study did not directly measure hormone changes after quitting. However, since smoking raises androgens, quitting should help normalize them over time. Most health improvements from quitting smoking develop gradually over weeks to months
Does smoking affect women’s hormones differently before and after menopause?
Smoking raised androgens in both pre- and postmenopausal women similarly. However, postmenopausal women showed a clearer dose-response pattern, meaning their hormone levels increased more predictably with lifetime smoking exposure
Why do scientists care about androgens and breast cancer?
Androgens are male-type hormones that influence breast tissue growth. Understanding how smoking raises androgens helps explain one biological pathway through which smoking increases breast cancer risk, potentially leading to better prevention strategies
Want to Apply This Research?
- Track smoking status weekly (current smoker, quit attempt, quit date, days smoke-free) alongside any health markers your doctor monitors, such as hormone levels if tested. This creates a personal record of your smoking journey and health changes
- Set a quit date within the next 30 days and use the app to log daily progress. Track triggers that make you want to smoke (stress, certain times of day, social situations) and plan alternative activities. Log each cigarette avoided as a small win to build motivation
- After quitting, track your progress in 1-week, 1-month, 3-month, and 6-month milestones. Note improvements in energy, breathing, or other health markers. If you slip, log it without judgment and refocus on your quit goal. Share progress with your healthcare provider at annual checkups
This research shows an association between smoking and higher androgen levels, but cannot prove that smoking causes these hormone changes or that these hormones directly cause breast cancer. This study was conducted on Italian women and may not apply equally to all populations. Individual hormone levels vary based on many factors. If you smoke or have concerns about breast cancer risk, consult your healthcare provider about personalized screening and prevention strategies. This article is for educational purposes and should not replace professional medical advice
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.