BACKGROUND: Traditional Chinese Medicine (TCM) has been used increasingly as complementary medicine in cancer care. Kuan-Sin-Yin (KSY) is a TCM decoction containing seven herbs known to cause immunomodulation or anticancer activity, and which are associated with the TCM concept of Qi and energy supply. Kuan-Sin-Yin has cytostatic effects on cancer cells in animal models. OBJECTIVE: The aim of this study is to evaluate the level of improvement in meridian energy and heart-rate variability (HRV) and to assess whether these observations are compatible with TCM theory. METHOD: A non-randomized controlled trial was designed with monitoring of the meridian electro-conductivity and heart-rate variability (HRV) to compare the efficacy of Kuan-Sin-Yin in the control and experimental groups. 52 patients were enrolled in this study. We also measured cancer-related symptoms and quality of life as secondary outcomes. RESULTS: We found that colon cancer patients who received KSY as complementary therapy benefitted with enhancement of meridian energy (Yin meridian: 27.90:35.45muA; p=0.014; Yang meridian: 27.09:33.55muA; p=0.024) and increases in HRV activity (78.40:129.04ms; SDNN: p=0.001) and parasympathetic tone(HF:1644.80:3217.92 ms(2); p=0.003; RMMSD:99.76:164.52ms; p=0.002). Cancer-related symptoms decreased (ECOG>1:46.2:7.7%; p=0.0001), and quality of life (KSY group: PCS 35.46:42.12, p=0.0001; MCS: 44.50:47.55, p=0.209) was improved with statistical significance. CONCLUSIONS: The correlation of positive results reflected in meridian energy and HRV activity confirms the positive role of complementary medicine of Kuan-Sin-Yin in cancer care.