Dancing and Diet Boost Health and Gut Microbes in Obese Breast Cancer Survivors

For women recovering from breast cancer, the side effects of treatment often linger long after therapy ends: weight gain, fatigue, weakened muscles, and a diminished quality of life. A new study now adds a striking twist to this picture, showing that breast cancer survivors with obesity carry a distinctly altered gut microbiome compared with both healthy women and women with obesity who never had cancer — and that a 12-week program combining dance classes with a personalized diet can meaningfully improve body composition, fitness, metabolic health, and quality of life, while nudging gut bacteria in a largely favorable direction.

The research, conducted at the Faculty of Physical Education and Sport at Comenius University in Bratislava and published in the journal Cancer Reports, is described by its authors as the first human study to examine the combined effects of physical activity and dietary intervention on the gut microbiome in breast cancer patients. It unfolded in two parts: a cross-sectional observational comparison of gut bacteria among three groups of women, and a randomized controlled trial testing the dance-and-diet intervention in breast cancer patients with obesity. The trial is registered as a clinical trial under number NCT07213271.

The observational component included 23 breast cancer patients with obesity in remission, with a mean body mass index of 32.43 kg/m², alongside 16 women with obesity but no cancer history (mean BMI 37.78 kg/m²) and 16 healthy controls (mean BMI 21.26 kg/m²). Stool samples were analyzed using sequencing of the V3–V4 region of the 16S rRNA gene, a standard technique that profiles bacterial communities by reading a stretch of DNA found in all bacteria. Reads were classified to the species level using the CLARK algorithm and reference databases built from SILVA and UNITE sequences. Alpha diversity, which measures the number and evenness of species within a single individual, was estimated with the Shannon and Chao1 indices, while beta diversity, which captures differences in community composition between individuals, was calculated using Bray–Curtis dissimilarity and tested with permutational multivariate analysis of variance.

The results were unambiguous. Healthy women had significantly higher Shannon diversity and Chao1 richness than either of the two groups with obesity, but the deeper story emerged in the compositional data. Breast cancer patients differed significantly in beta diversity from both control groups at every taxonomic level examined, from phylum to species, while the two control groups did not differ from each other at all. Group membership explained between roughly 8 and 12 percent of the variance in microbial composition. At the phylum level, breast cancer patients had significantly lower relative abundance of Bacteroidetes and higher abundance of Firmicutes compared with both controls. Perhaps most striking was Faecalibacterium prausnitzii, a health-associated, butyrate-producing bacterium that has been shown in laboratory studies to suppress the proliferation and invasion of breast cancer cells and to promote apoptosis. Its abundance was significantly lower in breast cancer patients with obesity than in the non-cancer controls with obesity, and Phocaeicola vulgatus, another beneficial species, was reduced compared with both control groups.

These findings matter because they suggest that something about the cancer itself, or its treatment, reshapes the gut ecosystem beyond what obesity alone explains. Previous studies had reported reduced microbial diversity in breast cancer patients and in people with obesity, but most comparisons had been made against normal-weight controls. By including a non-cancer control group with obesity, the Slovak team was able to separate the microbial signature associated with excess weight from the signature associated with cancer and its treatment — and the latter proved distinct. The authors note that cancer-related factors, including treatment exposures, may contribute to a compositional restructuring of the gut microbiome that obesity alone does not produce.

The interventional arm then asked whether lifestyle change could move this altered ecosystem. Forty breast cancer patients with obesity in remission were recruited between April and June 2025, and those who completed the study were randomly assigned either to a 12-week intervention or to a non-intervention control group. In the end, 13 women in the intervention group completed the program with at least 80 percent attendance at dance classes, and 10 women completed the study as controls. The dance program was demanding and structured: supervised sessions three times per week, each lasting 60 minutes, taught by certified professional dancers and incorporating choreographies from folkloric, Latin American, and contemporary genres. Alongside the dancing, participants received an individualized nutrition plan generated by nutrition software, prescribing 1200 to 1500 kcal per day based on measured resting metabolic rate, with 30 to 50 percent of energy from carbohydrates, 25 to 30 percent from fats, 20 to 30 percent from proteins, and 14 grams of fiber per 1000 kcal.

The physical results were substantial. Women in the intervention group lost an average of 4.04 kg of body weight, 1.45 units of BMI, and 3.29 kg of fat mass, with significant reductions also seen in visceral fat, waist and hip circumference, and the waist-to-hip ratio. Effect sizes for these changes were large. Metabolic markers improved in parallel: gamma-glutamyl transferase, a liver enzyme linked to metabolic dysfunction, fell significantly, and HOMA-IR, a mathematical index of insulin resistance calculated from fasting glucose and insulin, dropped from 2.06 to 1.70. The control group showed none of these changes. Cardiorespiratory fitness, measured with an incremental bicycle ergometer test to volitional exhaustion, rose by 3.3 mL/kg/min in maximal oxygen uptake, along with significant increases in maximal minute ventilation, maximal respiratory frequency, and maximal workload. Muscular performance improved as well, with gains in handgrip strength in the right hand, the 30-second arm curl test, and the 30-second chair stand test. The authors note that these fitness gains are clinically relevant, because physical function has been shown to predict survival in breast cancer patients.

Quality of life, measured with the internationally validated EORTC QLQ-C30 questionnaire and its breast cancer-specific BR23 module, told an equally compelling story. Within the intervention group, role functioning, fatigue, and body image all improved significantly. Compared with controls after treatment, the intervention group showed better role, emotional, and social functioning, less fatigue and pain, and fewer systemic treatment-related side effects, with improvements ranging from roughly 16 to 47 percent. Fatigue and pain are among the symptoms that most heavily burden survivors’ lives after cancer treatment, and the authors highlight the improvement in body image, which they suggest may have been fostered by the group-based nature of the dance classes, with their built-in social interaction and peer support.

The microbiome itself changed in subtler but intriguing ways. Total alpha diversity did not shift significantly in the intervention group, although it actually decreased in the controls, a decline the authors attribute possibly to natural temporal or seasonal variation. But the overall community composition diverged between the groups: beta diversity at the phylum level differed significantly between the post-intervention intervention and control groups, with a statistically significant pairwise difference and a modest proportion of variance explained by group membership. Within the intervention group, the abundance of Firmicutes decreased significantly, a shift the authors interpret as potentially favorable given that alterations in the Firmicutes-to-Bacteroidetes balance are frequently associated with metabolic regulation and obesity-related phenotypes. More specifically, two recognized beneficial species, Bifidobacterium pseudocatenulatum and Bifidobacterium animalis, increased significantly, while Klebsiella oxytoca, an opportunistic pathogen linked to cancer cachexia and inflammatory conditions, declined significantly. Members of Bifidobacterium are known to modulate host immune function and produce short-chain fatty acids that support gut barrier function.

One finding ran against expectations: the abundance of butyrate-producing bacteria, including Ruminococcus bromii and Ruminiclostridium hungatei, decreased significantly in the intervention group. These species contribute to resistant starch degradation and short-chain fatty acid production, so their decline contrasts with what might be predicted from a beneficial lifestyle intervention. The authors caution that this could reflect a specific ecological response to the combined intervention, or simply a chance finding arising from the many statistical comparisons made in a small pilot study, and they call for future work with metabolomics to determine whether total butyrate production was actually affected. Meanwhile, measurements of gut permeability, using serum zonulin as a proxy marker, showed a non-significant decreasing trend in the intervention group but a significant increase in the controls. Changes in zonulin were negatively correlated with beneficial bacteria such as Anaerobutyricum hallii, Bifidobacterium breve, and Streptococcus thermophilus, and positively correlated with potentially pathogenic groups including Proteobacteria — an expansion of which is commonly considered a hallmark of dysbiosis — and Neisseria.

The authors are candid about the study’s limitations. Combining dance and diet means the independent contribution of each component cannot be disentangled; a higher-than-expected dropout rate reduced the final sample size and statistical power; and 16S rRNA sequencing offers limited taxonomic resolution and no direct functional insight compared with whole-genome shotgun metagenomics. The p-values reported are unadjusted and exploratory in nature. Still, the trial’s breadth is unusual, spanning stool analysis, blood biochemistry, body composition, cardiopulmonary exercise testing, motor performance, dietary records, and validated quality-of-life questionnaires, and its inclusion of an obesity-matched non-cancer control group addresses a gap left by most prior microbiome studies in oncology.

The broader implications are considerable. Breast cancer is projected to rise from the 22nd to the 16th leading cause of death globally, with annual deaths expected to grow from 0.82 million in 2022 to 1.16 million by 2050, even as survival rates continue to improve — meaning more women than ever will live with the long-term consequences of treatment. Obesity in this population is consistently associated with increased risk of recurrence and worse overall survival, making interventions that simultaneously address weight, fitness, insulin sensitivity, and psychological well-being especially valuable. The image of middle-aged cancer survivors improving their VO2max and shrinking their visceral fat through folkloric and Latin dance is an appealing one, and the parallel microbial shifts — more Bifidobacterium, fewer Klebsiella — hint that the benefits of joyful movement may extend all the way down to the gut ecosystem. Larger, adequately powered trials with diet-only control groups and metagenomic sequencing, the authors conclude, are now needed to clarify the specific role of physical activity in shaping the microbiome during breast cancer survivorship.