New Research Explores Whether Short-Term Fasting Could Improve Ovarian Cancer Treatment Outcomes
Claudia Marchetti et al. Effects of short-term fasting compared to free diet in ovarian cancer patients: Results from a two-arm pilot randomized trial. J Clin Oncol 44, 5517-5517(2026).
Could the timing of meals around chemotherapy influence how well treatment works? New research suggests that short-term fasting before and after chemotherapy may improve treatment response in some patients with advanced ovarian cancer. While the findings are encouraging, researchers emphasize that larger studies are needed before fasting can be recommended as part of routine cancer care.
A small randomized clinical trial presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting found that women with advanced high-grade serous ovarian cancer who followed a supervised fasting schedule around chemotherapy experienced lower insulin levels, stronger tumor responses, and longer periods without their cancer progressing compared with women who maintained their usual diets.
Understanding the Study
Researchers in Italy investigated whether temporarily restricting food intake around chemotherapy could influence treatment effectiveness.
The study included 36 women with advanced high-grade serous ovarian cancer who were receiving chemotherapy with carboplatin and paclitaxel before surgery. This approach, known as neoadjuvant chemotherapy, aims to shrink or control cancer before an operation.
Participants were randomly assigned to one of two groups:
Short-term fasting group: Participants followed a supervised fasting schedule beginning 36 hours before chemotherapy and continuing until 24 hours afterward.
Regular diet group: Participants continued eating without study-imposed dietary restrictions.
Researchers examined insulin levels, chemotherapy response, progression-free survival, and changes in immune system activity.
What Did Researchers Find?
The results revealed several potentially important differences between the two groups.
1. Lower insulin levels
After three chemotherapy cycles, insulin levels decreased slightly in the fasting group but increased among patients following their regular diets.
Researchers believe this may be important because insulin-related signaling pathways can influence cancer cell survival and potentially affect how tumors respond to chemotherapy.
2. Stronger response to chemotherapy
Among participants who underwent surgery following chemotherapy, approximately 59% of those in the fasting group achieved the highest chemotherapy response score, compared with approximately 18% in the regular diet group.
This score measures how much cancer remains in examined tissue after chemotherapy. A higher response score indicates that treatment has been more effective at destroying tumor cells.
3. Longer progression-free survival
Fasting group Regular diet group
38 months 24 months
Median progression-free survival Median progression-free survival
Progression-free survival refers to how long patients live without their cancer worsening. Although the difference was encouraging, the study was small, and these estimates require confirmation in larger trials.
4. Possible benefits for the immune system
Researchers also identified changes in certain immune cell populations among fasting participants. These early findings suggest that fasting may influence the immune environment in ways that could support cancer treatment, although the mechanisms are not yet fully understood.
What Does This Mean for Patients?
These findings add to growing interest in understanding how nutrition, metabolism, and the immune system may influence cancer treatment.
However, fasting during chemotherapy is not currently an established treatment strategy for ovarian cancer.
The study included only 36 participants, and its primary goal was to evaluate changes in insulin levels rather than establish that fasting improves long-term survival. It also excluded certain patients, including those with diabetes, eating disorders, or a body mass index below 19.
For people undergoing chemotherapy, maintaining adequate nutrition, hydration, muscle mass, and strength is essential. Some patients already struggle with nausea, appetite loss, weight loss, or malnutrition, and prolonged fasting could make these challenges worse.
Patients should not begin fasting during chemotherapy without first discussing it with their oncology team and, ideally, an oncology registered dietitian. Any potential benefit must be weighed against individual nutritional needs, medical conditions, and treatment-related risks.
Looking Ahead
Although preliminary, this research highlights an important area of investigation: whether carefully supervised dietary interventions could eventually help improve the effectiveness of existing cancer treatments.
Larger clinical trials will be needed to determine which patients might benefit, how fasting affects treatment tolerance and nutritional health, and whether these early findings translate into meaningful long-term improvements.
For now, the study offers a promising direction for future research rather than a change in standard treatment recommendations.
