Medical Bulletin 02/Jul/2025 - Video

Here are the top medical news for the day:

Study Links Hormone Therapy to Breast Cancer Risk in Women Under 55

A new large-scale study published in Lancet Oncology has found that two commonly used hormone therapies may affect breast cancer risk in women under the age of 55. Scientists at the National Institutes of Health (NIH) revealed that unopposed estrogen hormone therapy (E-HT) is linked to a reduced risk of breast cancer, while estrogen plus progestin hormone therapy (EP-HT) appears to increase the risk.

E-HT is generally recommended only for women who have had a hysterectomy due to its known association with uterine cancer. EP-HT, on the other hand, is often prescribed to women with an intact uterus to offset the risks of estrogen alone.

The researchers conducted a comprehensive analysis involving over 459,000 women under 55 from North America, Europe, Asia, and Australia. Their results showed that women who used E-HT had a 14% lower incidence of breast cancer compared to non-users, with the protective effect more pronounced in those who started at younger ages or used it longer. Conversely, EP-HT users faced a 10% higher rate of breast cancer, with the risk climbing to 18% for those who used it for more than two years.

According to the study, the estimated cumulative risk of developing breast cancer before age 55 was about 3.6% for E-HT users, 4.1% for non-users, and 4.5% for EP-HT users. Importantly, the increased risk associated with EP-HT was especially evident in women who had not undergone hysterectomy or oophorectomy.

“Hormone therapy can greatly improve the quality of life for women experiencing severe menopausal symptoms or those who have had surgeries that affect their hormone levels,” said lead author Katie O’Brien, Ph.D., of NIH’s National Institute of Environmental Health Sciences (NIEHS). Our study provides greater understanding of the risks associated with different types of hormone therapy, which we hope will help patients and their doctors develop more informed treatment plans.”

The study supports earlier findings on hormone therapy and breast cancer in older women and extends those insights to younger women, offering critical evidence to guide clinical decision-making.

Reference: O’Brien, K., et al. “Hormone therapy use and young-onset breast cancer: a pooled analysis of prospective cohorts included in the Premenopausal Breast Cancer Collaborative Group.” Lancet Oncol 2025; 26: 911–23.

Are Omega-6 Fats Really Inflammatory? New Study Says No

A recent study published in Nutrients provides compelling evidence that challenges the widely held belief that omega-6 fatty acids, particularly linoleic acid, are proinflammatory. Researchers found that higher blood levels of linoleic acid and arachidonic acid both omega-6 fatty acids were actually associated with lower levels of several inflammation-related biomarkers, contradicting the popular narrative that these fats promote chronic inflammation.

This new research sought to test that assumption directly by examining whether higher intakes and thus higher blood levels of linoleic acid and arachidonic acid are truly linked to increased markers of inflammation and oxidative stress.

The study used cross-sectional data from the Framingham Offspring Study, a long-term cohort that has tracked the health of participants since 1971. Blood samples from 2,700 individuals were analyzed for levels of linoleic acid and arachidonic acid, alongside 10 biomarkers of inflammation and oxidative stress.

The findings were clear: higher levels of linoleic acid were significantly associated with lower levels of five biomarkers of inflammation. Similarly, higher arachidonic acid levels correlated with reduced levels of four markers. Importantly, neither fatty acid was linked to any increases in inflammatory or oxidative stress markers.

“These new data show clearly that people who have the highest levels of linoleic acid and arachidonic acid in their blood are in a less inflammatory state than people with lower levels,” said study investigator William S. Harris, PhD. “This finding is exactly the opposite of what one would expect if omega-6 fatty acids were ‘proinflammatory’ – in fact, they appear to be anti-inflammatory.”

The study concludes that the negative perception of omega-6 fats lacks scientific basis and that increasing, rather than reducing, their intake could support better inflammatory health.

Reference: Lai, H. T. M., Ryder, N. A., Tintle, N. L., Jackson, K. H., Kris-Etherton, P. M., & Harris, W. S. (2025). Red Blood Cell Omega-6 Fatty Acids and Biomarkers of Inflammation in the Framingham Offspring Study. Nutrients, 17(13), 2076. https://doi.org/10.3390/nu17132076

Early Bedtimes May Boost Physical Activity: Study Finds

Going to bed earlier than usual could lead to more physical activity the next day, according to a new study led by Monash University and published in Proceedings of the National Academy of Sciences (PNAS). The research examined how both habitual and nightly variations in sleep timing and duration relate to next-day physical activity, offering important insights for public health strategies.

The primary study involved nearly 20,000 participants who wore WHOOP biometric devices for one year, generating almost six million nights of data. These wrist-worn devices provided objective, real-time measurements of both sleep and physical activity.

Results showed that earlier bedtimes were consistently associated with higher levels of physical activity. For instance, individuals who typically went to bed around 9pm engaged in approximately 30 more minutes of moderate-to-vigorous physical activity each day compared to those who stayed up until 1am. Even compared to the study average of 11pm, those with 9pm bedtimes logged nearly 15 extra minutes of activity.

Lead author Dr Josh Leota from Monash University’s School of Psychological Sciences noted that this pattern may be particularly relevant for people whose natural sleep preferences conflict with standard work hours. “Standard 9-to-5 routines can clash with the natural sleep preferences of evening types, leading to social jetlag, poorer sleep quality, and increased daytime sleepiness – which can all reduce motivation and opportunity for physical activity the next day,” Dr Leota said.

Importantly, the study found that when individuals went to bed earlier than usual without reducing their overall sleep duration—they recorded the highest levels of next-day physical activity. “These insights carry meaningful implications for public health,” Dr Leota added. “A holistic approach that recognises how these two essential behaviours interact may lead to better outcomes for individual and community health.”

The findings suggest that encouraging earlier bedtimes could be a simple yet effective strategy to promote healthier, more active lifestyles.

Reference: J. Leota, M.É. Czeisler, F. Le, D.M. Presby, E.R. Capodilupo, H. Scott, J.F. Wiley, S.P.A. Drummond, S.M.W. Rajaratnam, & E.R. Facer-Childs, Sleep duration and timing are associated with next-day physical activity: Insights from two large-scale wearable sensor studies, Proc. Natl. Acad. Sci. U.S.A. 122 (27) e2420846122, https://doi.org/10.1073/pnas.2420846122 (2025).