Andrea Romanos-Nanclares, PhD , of the Channing Division of Network Medicine within the Department of Medicine at Mass General Brigham, is the lead author of a paper published in The Lancet Obstetrics , Gynaecology, & Women’s Health , “ The Nurses’ Health Studies: a half-century of discovery in women’s health .” A. Heather Eliassen, ScD , of Mass General Brigham and Harvard T.H. Chan School of Public Health, is the senior author.
Q: What challenges or unmet needs make this study important?
The Nurses’ Health Studies (NHS, NHSII and NHS3) began in 1976 to investigate the long-term effects of oral contraceptives. They have since evolved into influential ongoing studies examining a broad range of factors affecting women’s health and disease.
Unlike traditional research designs, the Nurses’ Health Studies have provided a unique opportunity to prospectively follow large populations of women over decades, while repeatedly measuring diet, lifestyle, reproductive factors, medications, environmental exposures and other health-related factors. This approach has allowed us to study not only whether certain exposures are associated with disease, but also how timing, duration and changes in those exposures influence health across the life course.
The studies have also continually incorporated new technologies, biospecimens, biomarkers and statistical methods. This combination of long-term follow-up and methodological innovation has generated evidence that has had a profound impact on society — shaping clinical guidelines, public health recommendations, health policies, risk prediction and disease prevention across many areas of medicine.
Q: What central question(s) were you investigating?
What have the Nurses’ Health Studies taught us about the factors shaping women’s health across the life course, and how has that evidence changed over five decades? We examined contributions across diet and lifestyle, cancer, cardiovascular and metabolic disease, reproductive health, mental health, environmental exposures, cancer survivorship and healthy aging, among others.
We also asked how advances in methods — from repeated dietary measurements to metabolomics, proteomics, microbiome research and wearable technologies — have allowed us to ask increasingly complex scientific questions. In other words, we wanted to look not only at individual discoveries, but also at how the studies themselves evolved as science evolved.
Q: What methods or approach did you use?
To comprehensively review the scientific contributions of the Nurses’ Health Studies, we used a database to identify and review relevant publications, covering research from 1984 to 2026, along with relevant papers from the authors’ own files. We synthesized findings across the NHS, NHSII and NHS3.
Q: What did you find?
Our review highlights key findings of the Nurses’ Health Studies, including the following:
Q: What are the real-world implications, particularly for patients?
Beyond contributing to the U.S. FDA’s ban on industrial trans fats, findings from the Nurses’ Health Studies have supported major clinical and public health recommendations worldwide. Evidence has informed American Heart Association (AHA) recommendations on cardiovascular health, American Diabetes Association (ADA) guidance on diabetes prevention and international evaluations by the World Health Organization (WHO) and International Agency for Research on Cancer, including the classification of processed meat as a carcinogenic hazard.
For patients, one of the most important messages is that health is influenced by many factors over the course of a lifetime and some of these factors are modifiable. The Nurses’ Health Studies have provided evidence supporting recommendations around diet, physical activity, weight management, chronic disease prevention and survivorship. They have also shown that prevention is not simply about avoiding one disease: the same healthy behaviors can influence cardiovascular health, diabetes, cancer, cognitive health and longevity.
For people who have already been diagnosed with cancer, the research also suggests that what happens after diagnosis matters. For example, physical activity after diagnosis has been associated with lower mortality across several cancers. Ultimately, the goal is to translate long-term population research into information that can support prevention and more comprehensive survivorship care.
Q: What part of this work feels most meaningful to you personally?
What feels most meaningful to me is the opportunity to study factors that may help prevent breast cancer and improve the lives of women who are diagnosed. Breast cancer is such a personal disease for so many people, and I find it especially motivating that the Nurses’ Health Studies allow us to look at potentially modifiable factors, both before and after diagnosis. Being able to contribute to research that may help women reduce their risk of developing breast cancer, or potentially live longer and healthier lives after a diagnosis, gives this work a very tangible purpose.
I also value that these studies let us look beyond a single risk factor and understand how different aspects of lifestyle and biology may work together over the long term.
Authorship: In addition to Romanos-Nanclares and Eliassen, Mass General Brigham authors include Jorge Chavarro, Frank Hu, Meir Stampfer, Bernard Rosner and Jae Hang. Additional authors include Walter Willett.
Paper cited: Romanos-Nanclares, A. , et al . “The Nurses’ Health Studies: a half-century of discovery in women’s health.” The Lancet Obstetrics, Gynaecology, & Women’s Health . DOI: 10.1016/S3050-5038(26)00220-7
Funding: The Nurses’ Health Study is supported by the National Institutes of Health (NIH) (UM1 CA186107, P01 CA87969, R01 CA49449, R01 HL034594 and R01 HL088521). Nurses’ Health Study II is supported by the NIH (U01 CA176726, U01 HL145386 and R01CA67262). Nurses’ Health Study 3 is supported by the NIH (U01 HL145386 and R24 ES028521). The Growing Up Today Study is supported by the NIH (U01 HL145386 and R01 HD057368).
Disclosures: Romanos-Nanclares is supported by an NIH grant (R00CA286891) and a Nutrition Obesity Research Center at Harvard pilot and feasibility grant (P30DK040561). Eliassen received grant funding to their institution from the NIH for support related to the present manuscript. Additional disclosures can be found in the paper.
The Lancet
Randomized controlled/clinical trial
People
The Nurses’ Health Studies: a half-century of discovery in women’s health
1-Oct-2026
Disclosures: Romanos-Nanclares is supported by an NIH grant (R00CA286891) and a Nutrition Obesity Research Center at Harvard pilot and feasibility grant (P30DK040561). Eliassen received grant funding to their institution from the NIH for support related to the present manuscript. Additional disclosures can be found in the paper.