Short-Term Fasting Around Chemotherapy Improves Response and PFS in Advanced Ovarian Cancer: Pilot Trial
Key Insights
A pilot randomized trial found short-term fasting before and after chemotherapy reduced insulin levels in patients with high-grade serous ovarian cancer (search), with a mean change of –1.12 µIU/mL vs +9.76 µIU/mL in the free-diet group (P = .01).
Patients in the fasting arm achieved a significantly higher complete/near-complete pathologic response rate at interval cytoreductive surgery (58.8% vs 17.6%; P = .03).
Median progression-free survival was 38 months with short-term fasting compared to 24 months with a free diet (P = .045), with no significant differences in chemotherapy toxicity between groups.
Short-term fasting before and after each cycle of neoadjuvant chemotherapy was associated with lower insulin levels, improved pathologic response, and longer progression-free survival (PFS) in patients with advanced high-grade serous ovarian cancer (search), according to results from a two-arm pilot randomized trial presented at the 2026 ASCO Annual Meeting (Abstract 5517).
“Despite advancements in surgery and chemotherapy, patients with advanced ovarian cancer still face poor outcomes,” said lead study author Claudia Marchetti, MD, of the Fondazione Policlinico Universitario Agostino Gemelli IRCCS in Rome, Italy, during a press briefing. “This highlights the urgent need for safe, low-cost, and easily implementable strategies that can enhance treatment efficacy and improve patient prognosis.”
Study Design and Patient Population
The prospective trial was conducted at a single center in Rome and enrolled 36 women (mean age, 62 years) with newly diagnosed advanced high-grade serous ovarian cancer (search) who were not suitable for primary cytoreductive surgery and required neoadjuvant chemotherapy. Eligible patients had a body mass index of at least 19 kg/m² and good general health. Major exclusion criteria included diabetes mellitus, food allergies, eating disorders, and malnutrition.
All participants received carboplatin- and paclitaxel-based neoadjuvant chemotherapy and were randomly assigned to either short-term fasting (n=18) or a free diet (n=18), with evaluation for interval cytoreductive surgery after three cycles. A planned ketogenic diet arm was closed early due to low compliance and preclinical data suggesting a ketogenic diet may promote tumor growth.
Short-term fasting was defined as fasting from 36 hours before chemotherapy until 24 hours after the end of each chemotherapy cycle, with a maximum daily intake of 350 kcal. Patients in the fasting group could consume unrestricted water and herbal tea, up to 2 liters of vegetable juice, and small amounts of light vegetable broth. Between chemotherapy sessions, all patients ate regularly.
Insulin Reduction and Primary Endpoint
The primary endpoint—mean difference in insulin level variations between groups after three cycles of neoadjuvant chemotherapy—was met. Insulin levels increased by 9.76 µIU/mL in the free-diet group (from a mean baseline of 8.7 µIU/mL to 18.5 µIU/mL) but decreased by 1.12 µIU/mL in the short-term fasting group (from a mean baseline of 10.7 µIU/mL to 9.59 µIU/mL), yielding a statistically significant between-group difference (P = .01).
Patients who did not undergo interval cytoreductive surgery after three cycles had a greater increase in insulin levels than those who underwent surgery: 11.46 vs 1.35 µIU/mL (P = .033).
Pathologic Response and Survival Outcomes
Short-term fasting was associated with significantly improved pathologic response. At interval cytoreductive surgery, a chemotherapy response score of 3—indicating complete or near-complete response—was observed in 58.8% of patients in the short-term fasting arm compared with 17.6% in the free-diet arm (P = .03).
After a median follow-up of approximately 18 months, median PFS was 38 months in the short-term fasting arm versus 24 months in the free-diet arm (P = .045).
Immune Profiling and Safety
Translational analyses revealed lower levels of immunosuppressive granulocyte and monocyte subsets in the short-term fasting arm, suggesting that fasting may create a more favorable immune environment during chemotherapy. “This suggests a potentially more favorable immune environment during chemotherapy,” Marchetti said.
The most common adverse effects—low blood cell counts and low hemoglobin levels—occurred at similar rates in both groups. The investigators reported no statistically significant differences in hematologic or nonhematologic toxicities between the fasting and free-diet groups, indicating that short-term fasting during chemotherapy was feasible and well tolerated.
Expert Commentary and Future Directions
“Fasting during chemotherapy is an area of growing research interest. This pilot randomized clinical trial showed that short-term fasting before and after each chemotherapy cycle led to a reduction in insulin levels after 3 neoadjuvant chemotherapy cycles and improved pathologic response and progression-free survival in patients with ovarian cancer,” said Eleonora Teplinsky, MD, FASCO, Head of Breast and Gynecologic Medical Oncology at Valley-Mount Sinai Comprehensive Cancer Care and an ASCO Expert in gynecologic cancers. “While this is a small study, the findings are encouraging, support earlier data, and highlight a promising area of cancer research, with larger clinical trials now needed to build on these results.”
Eric J. Small, MD, FASCO, 2025–2026 ASCO President, underscored the potential clinical relevance: “What’s so interesting about this study, and why we’ve selected it for the program, is that it had significant clinical impact, and this is a great example of a very simple intervention that has benefit and can be undertaken and implemented anywhere in the world. It’s not an expensive new drug. And yet, it has the potential to really have an impact on this cancer.”
According to the authors, the findings provide a strong rationale for longer follow-up and larger multicenter randomized studies to validate whether short-term fasting can improve outcomes in patients with ovarian cancer.