STEM-Talk
Episode 188: Marina Walther-Antonio discusses the microbiome’s role in women’s health and cancer
// Oct 31, 2025
Today we have Dr. Marina Walther-Antonio, a Mayo Clinic researcher who investigates the role of the microbiome in cancer and reproductive health, particularly endometrial and ovarian cancers. According to the World Cancer Research Fund International, endometrial and ovarian cancers are among the top 10 most prevalent cancers in women worldwide, and there are still no standard screenings for early detection.
Marina is an assistant professor in the Department of Surgery and the Mayo Clinic Center for Individualized Medicine Microbiome Program. She has a joint appointment in the department of Obstetrics and Gynecology.
Today we talk to Marina about how she and her colleagues are utilizing the methodologies of environmental microbiology and technologies used in astrobiology to improve our understanding of endometrial and ovarian cancers. Through her investigations into the microbiome, she and her team are developing early detection tests that will enable clinical interventions before certain cancers develop.
Show notes:
[00:03:13] Dawn opens our interview asking Marina about the history of her interest in extraterrestrial life. [00:05:49] Dawn mentions that Marina did her undergraduate studies in Portugal at the University of Aveiro, where she majored in biology. Dawn asks why Marina chose biology as her major. [00:06:39] Ken explains that the undergraduate programs at Aveiro University require students to do a year of research outside the university and asks Marina about her experience with this requirement. [00:08:34] Ken explains that while Marina was conducting her internship at NASA Ames Research Center, there were several projects under way at the astrobiology institute, with the one that Marina was assigned to looking at a Mars analogue site in Oregon’s Warner Valley. Ken asks what kind of work Marina did on this project. [00:10:06] Ken asks Marina why after earning a master’s degree in microbiology from Indiana University, she went to Washington State University to earn a Ph.D. in environmental sciences. [00:13:29] Dawn asks about Marina’s Ph.D. research on microbialites, which are microbial structures that can thrive at the bottom of certain freshwater lakes and other extreme environments. [00:16:02] Dawn explains that just as Marina began researching microbial populations, the Mayo Clinic Center for Individualized Medicine created a microbiome program. Dawn asks Marina about the circumstances that led to her joining Mayo. [00:19:05] Dawn mentions that Dr. Claire Fraser, the director of Maryland’s Institute for Genome Sciences pointed out in Episode 32 of STEM-Talk that there are more microbes on a single person’s hands than there are people on Earth, as well as the fact that our gut is home to more than 100 trillion bacteria. Dawn asks Marina to talk about this microbial side of humanity. [00:21:51] Ken mentions that if listeners are interested in learning more about the microbiome and how it affects human health, they should listen to Episodes 20 and 168 with Dr. Alessio Fasano. Ken asks Marina to give a short overview of the microbiome. [00:25:37] Dawn asks Marina how the focus of her research shifted to the role of the microbiome in cancer and reproductive health. [00:29:00] Dawn explains that endometrial and ovarian cancers are among the top 10 most prevalent cancers in women worldwide; with ovarian cancer being the most common gynecological malignancy and the fifth leading cause of death due to cancer in women in the nation. Dawn goes on to explain that in a 2023 paper Marina investigated the area of microbiome that is associated with ovarian cancer to better understand the microbiome’s potential in early detection. Dawn asks Marina to talk about this study and its findings. [00:35:55] Given the small scale and sample size of her initial study, Ken asks Marina what her ideal follow-up study would look like. [00:38:37] Ken mentions that in 2019 Marina published the results of a study that found that post-menopause is a key factor in the composition of endometrial cancer microbiome. This study also investigated the impact of patient factors on the microbiome, including menopausal status, BMI, and vaginal pH balance. Ken asks Marina to elaborate on the findings. [00:44:13] Dawn notes that there is no standard screening for early detection of ovarian and endometrial cancers despite their prevalence worldwide. Dawn asks Marina about the work she and her colleagues are engaged in in this space. [00:47:17] Dawn explains that prior to Marina’s aforementioned study, vaginal pH had not been associated as a risk factor in endometrial cancer. Dawn goes on to explain that variations in microbial compositions are implicated in a number of gynecologic and obstetric diseases. Marina’s core question was that since the vaginal microbiome is so crucial to women’s health, why then do vaginal microbial profiles vary strikingly from person to person. This question, as Dawn explains, led to a study and 2020 paper titled “Daily Vaginal Microbiota Fluctuations Associated with Natural Hormonal Cycle, Contraceptives, Diet, and Exercise.” Dawn asks Marina to talk about this study. [00:54:23] Ken asks Marina about her finding that exogenous hormones in contraceptives may affect vaginal microbiota. [00:56:42] Dawn asks Marina about future research that will stem from her study. [01:00:29] Dawn asks Marina about her job as director of Mayo’s mentorship and Ph.D. program, and her passion for mentorship. [01:05:24] Given her accomplished and varied career, Ken asks Marina what advice she has for young people beginning their careers in science. [01:10:06] Circling back to Marina’s original interest in the search for extraterrestrial life, Ken explains that among the NASA scientists we’ve had on STEM-Talk there is disagreement on our chances of discovering intelligent life. While our guest Ed Wiler is confident that we will be able to prove the existence of life off earth within the next 20-30 years, Pascal Lee says he doesn’t think it is likely that we will discover intelligent or complex life anytime soon. Ken asks Marina to weigh in on the matter.Links: