More isn't always better: lessons from a lifestyle intervention for Latina breast cancer survivors

Breast cancer is the most common cancer among Latina women in the United States, and surviving it is only part of the battle. After treatment ends, survivors face elevated risks of recurrence and other chronic diseases, risks that can be meaningfully reduced through healthy eating and regular physical activity. Yet for Latina breast cancer survivors, evidence-based, culturally tailored lifestyle programs have been scarce. A new study published in the Journal of the Academy of Nutrition and Dietetics takes an important step toward filling that gap, and its results are more nuanced than researchers expected.

The ¡Mi Vida Saludable! ("My Healthy Life!") trial enrolled 167 Latina breast cancer survivors living in New York City between 2016 and 2018. The women were randomized into one of four groups: in-person classes only, digital health (eHealth) communications only, a combination of both, or a control group. All participants received a Fitbit activity tracker and a one-on-one health coaching session reviewing nutrition and physical activity guidelines for cancer survivors.

The in-person component consisted of four four-hour weekly sessions, an intensive but condensed experience featuring nutrition and physical activity education, hands-on cooking classes led by a trained chef, dance or exercise sessions, grocery store visits, and shared meals. Everything was conducted in Spanish, with simultaneous English translation. The eHealth component ran for eleven months and included motivational text messages sent two to three times per week, bimonthly newsletters delivered by email, and access to two bilingual websites offering recipes and accessible movement programs designed for cancer survivors.

At twelve months, the results told a complicated story. Women who attended the in-person classes showed a 10% increase in daily fruit and vegetable intake, while those in the control group saw a 44% decrease. The hands-on, community-centered format appeared to work, at least for diet. The eHealth-only group, however, showed no significant improvement in fruit and vegetable consumption compared to controls. Nor did the combination group — a finding that surprised the research team. "More support does not always mean more effective support," says lead author Dr. Heather Greenlee of Fred Hutchinson Cancer Center. The addition of eHealth to in-person classes did not amplify the benefit, and in this case, might even have negatively affected the benefit seen for those who only attended in person.

The physical activity findings were perhaps the most striking. By twelve months, women in the control group had increased their moderate-to-vigorous physical activity by 53%, while women who received both in-person and eHealth components actually decreased theirs by 34%. The control group– who received only a Fitbit and a single thirty-minute coaching session– outpaced every intervention arm in getting moving.

How do you explain a control group that moved more than the intervention groups? The researchers offer several possibilities. The trial was not blinded, meaning women who knew they hadn't been randomized to a diet or exercise program may have felt motivated to increase their own physical activity. Self-reported physical activity is also notoriously prone to overestimation, and New York City residents may already be more physically active than breast cancer survivors in other regions — limiting how much room there was to improve.

As for the eHealth component, low engagement likely played a role. Only about 55% of participants in those arms responded to even one of the four nutrition goal-setting text messages. And because the study ran from 2016 to 2019, the technology available at the time made it impossible to track whether emails were actually opened and read. Notably, among those who did complete exit interviews, 79% said the text messages and newsletters were somewhat or very helpful– suggesting the content resonated, but reaching people consistently remains a challenge.

The ¡Mi Vida Saludable! trial was notable for its scale, cultural attunement, and design rigor. "The Mi Vida Saludable study was one of the first trials to use a factorial design,” says Dr. Greenlee. Factorial design tests multiple intervention components simultaneously, in this context to study lifestyle change within the chosen population, and it achieved an impressive 93% retention rate over twelve months. But the findings make clear that even well-designed, culturally adapted programs leave room for improvement. "More work needs to be done to identify which supports are needed to help this group of cancer survivors achieve and maintain nutrition and physical activity behaviors," Dr. Greenlee says.

The team is already building on what they learned. An ongoing trial called the VIDA study is now testing an adaptive intervention– using a SMART (Sequential, Multiple Assignment, Randomized Trial) design– an approach that randomizes participants multiple times at key decision points throughout the trial, adjusting the intervention based on how each person is responding, rather than keeping everyone on the same fixed protocol regardless of their progress. The VIDA study is grounded in a culturally adapted version of the Diabetes Prevention Program and delivered via Zoom, including twenty-six classes over a year, hands-on experiential learning, one-on-one health coaching, and take-home toolkits with foods and tools for participants to try.

For the millions of Latina women navigating life after breast cancer, research like this matters, not just for the answers it provides, but for the questions it keeps asking.

This work was supported by the National Institutes of Health National Cancer Institute and the National Center for Advancing Translational Sciences. Additional sources of funding were provided by the Herbert Irving Comprehensive Cancer Center Avon grant. The Fitbit Zip devices were provided by Fitbit (Fitbit, Inc, USA).

Fred Hutch/University of Washington/Seattle Children’s Cancer Consortium Member Dr. Heather Greenlee contributed to this research.

Greenlee, H., Santiago-Torres, M., Contento, I., Koch, P. A., Rillamas-Sun, E., Gray, H. L., Brickman, A. M., Gaffney, A. O., Thomson, C. A., Crane, T. E., Dominguez, N., Sepulveda, J., Marín-Chollom, A. M., Paul, R., Shi, Z., Ulanday, K. T., Accordino, M (2025). ¡Mi Vida Saludable!: Results of a Randomized, Controlled, 2 × 2 Factorial Trial of an In-Person and eHealth Diet and Physical Activity Intervention in Latina Breast Cancer Survivors. Journal of the Academy of Nutrition and Dietetics, 126(5), 156260. Advance online publication.