ASCO 2026: Short-Term Fasting During Neoadjuvant Chemotherapy May Improve Outcomes in Advanced Ovarian Cancer

Short-term fasting (STF) around the time of chemotherapy may improve treatment response and prolong progression-free survival (PFS) in women with advanced ovarian cancer, according to results from a prospective randomized pilot trial presented at the 2026 ASCO Annual Meeting (Abstract 5517). Claudia Marchetti, MD, of Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, and colleagues found that fasting produced favorable metabolic changes, enhanced pathologic response to chemotherapy, and was associated with immune changes that may help explain its clinical benefit.

Evidence has increasingly shown that fasting can suppress insulin-driven prosurvival signaling, potentially making cancer cells more susceptible to chemotherapy while preserving normal tissues. Although preclinical studies have suggested such benefits, limited clinical evidence has been available regarding the metabolic, oncologic, and immunologic effects of STF in patients with ovarian cancer.

Study Details

In this single-center, prospective, randomized pilot trial, investigators enrolled women with newly diagnosed advanced high-grade serous ovarian cancer receiving carboplatin/paclitaxel–based neoadjuvant chemotherapy. Eligible patients had a body mass index of at least 19 kg/m², while those with diabetes mellitus, food allergies, or eating disorders were excluded. Participants were randomly assigned to either an STF regimen—fasting for 36 hours before and 24 hours after each chemotherapy cycle—or a free diet. The primary endpoint was reduction in insulin levels after three cycles of neoadjuvant chemotherapy. The study was powered to enroll 17 patients per arm, and 18 patients in each group completed the first three cycles of chemotherapy.

Key Takeaways

Baseline clinical characteristics and insulin levels were similar between the treatment groups. Following three cycles of neoadjuvant chemotherapy, insulin levels increased among patients assigned to the free diet but decreased among those undergoing STF (+9.76 vs –1.12 µIU/mL; P = .01). In addition, patients who were not able to undergo interval cytoreductive surgery after three chemotherapy cycles experienced significantly greater increases in insulin than those who proceeded to surgery (+11.46 vs +1.35 µIU/mL; P = .033).

Clinical outcomes also favored the fasting strategy. At interval cytoreductive surgery, 58.8% of patients in the STF arm achieved a chemotherapy response score of 3, compared with 17.6% of those receiving a free diet (P = .03). After a median follow-up of 18 months, median PFS, a secondary endpoint, was 38 months in the STF group vs 24 months in the free diet group (P = .045). Exploratory immune profiling further showed that STF limited immunosuppressive immune cell subsets associated with chemotherapy response.

The investigators concluded: “The primary endpoint was met. STF induced a favourable metabolic shift and was associated with improved pathological response and prolonged PFS, alongside immune modulation. These findings provide a strong rationale for larger randomized trials evaluating STF in [ovarian cancer].”

DISCLOSURE: For full disclosures of the study authors, visit coi.asco.org.

2026 ASCO Annual Meeting

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