Experimental: true acupuncture + standard quadruple antiemetic therapy

The experimental group received electroacupuncture (EA) combined with a standard quadruple antiemetic regimen comprising Olanzapine (2.5 mg orally daily, days 1-4), dexamethasone (10 mg intravenously day 1; 7.5 mg intravenously days 2-3), a 5-HT₃ antagonist (palonosetron 0.25 mg intravenously or 0.5 mg orally, or ondansetron 8 mg intravenously or 8 mg orally twice, or tropisetron 5 mg intravenously, all on day 1), and an NK₁ antagonist (fosaprepitant 150 mg intravenously, or aprepitant 130 mg intravenously, or oral aprepitant 125 mg day 1 then 80 mg days 2-3, or netupitant 300 mg orally day 1). EA was applied at Zusanli (ST36), Neiguan (PC6), Hegu (LI4), and Zhaohai (KI6) with insertion depths of 20 mm, 15 mm, 20 mm, and 5 mm respectively, using continuous wave mode at 2 Hz and current intensity ≤10 mA (tolerance-adjusted) for 30 minutes per session. Treatment started 1-2 hours pre-chemotherapy on day 1 and continued daily at 9:00-10:00 on days 2-4, totaling four sessions per cycle.

Placebo_comparator: sham acupuncture + standard quadruple antiemetic therapy

The control group received sham electroacupuncture combined with the identical standard quadruple antiemetic regimen (drug components and dosages identical to the experimental group). The sham intervention protocol consisted of: (1) superficial needle insertion at non-acupoint locations adjacent to the authentic acupoints (ST36, PC6, LI4, and KI6); (2) attachment of non-functional electrodes using deactivated electroacupuncture devices with identical appearance to active units; while maintaining identical treatment duration (30 minutes/session) and schedule (pre-chemotherapy on day 1 followed by daily sessions on days 2-4) as the true electroacupuncture group.