Colon cancer survival with herbal medicine and vitamins combined with standard therapy in a whole-systems approach: ten-year follow-up data analyzed with marginal structural models and propensity score methods

Abstract

Although localized colon cancer is often successfully treated with surgery, advanced disease requires aggressive systemic therapy that has lower effectiveness. Approximately 30% to 75% of patients with colon cancer use complementary and alternative medicine (CAM), but there is limited formal evidence of survival efficacy. In a consecutive case series with 10-year follow-up of all colon cancer patients (n = 193) presenting at a San Francisco Bay-Area center for Chinese medicine (Pine Street Clinic, San Anselmo, CA), the authors compared survival in patients choosing short-term treatment lasting the duration of chemotherapy/radiotherapy with those continuing long-term. To put these data into the context of treatment responses seen in conventional medical practice, they also compared survival with Pan-Asian medicine + vitamins (PAM+V) with that of concurrent external controls from Kaiser Permanente Northern California and California Cancer Registries. Kaplan-Meier, traditional Cox regression, and more modern methods were used for causal inference-namely, propensity score and marginal structural models (MSMs), which have not been used before in studies of cancer survival and Chinese herbal medicine. PAM+V combined with conventional therapy, compared with conventional therapy alone, reduced the risk of death in stage I by 95%, stage II by 64%, stage III by 29%, and stage IV by 75%. There was no significant difference between short-term and long-term PAM+V. Combining PAM+V with conventional therapy improved survival, compared with conventional therapy alone, suggesting that prospective trials combining PAM+V with conventional therapy are justified.

Figure 1. Survival in colon cancer, short-term versus long-term PAM+V and external controls

Abbreviations: PAM+V, Pan-Asian medicine + vitamins; PS, Pine Street Clinic; KPNC, Kaiser Permanente Northern California; CCR, California Cancer Registry.

Figure 2

Colon cancer survival, showing all treatment combinations of PAM+V and surgery, using California Cancer Registry patients as external controls Abbreviation: PAM+V, Pan-Asian medicine plus vitamins.

Figure 3

Colon cancer survival, showing all treatment combinations of PAM+V and chemotherapy, using California Cancer Registry patients as external controls Abbreviation: PAM+V, Pan-Asian medicine plus vitamins.

Figure 4

Colon cancer survival, showing all treatment combinations of PAM+V and radiotherapy, using California Cancer Registry patients as external controls Abbreviation: PAM+V, Pan-Asian medicine plus vitamins.

Figure 5

Colon cancer survival, showing all treatment combinations of PAM+V and any conventional therapy, using California Cancer Registry patients as external controls Abbreviation: PAM+V, Pan-Asian medicine plus vitamins.

Figure 6

Colon cancer survival, comparing PAM+V patients initially treated at PS with those followed up at other CAM centers Abbreviation: PAM+V, Pan-Asian medicine plus vitamins; PS, Pine Street Clinic; CAM, complementary and alternative medicine.

Figure 7

Colon cancer survival, comparing patients treated with long-term and short-term PAM+V with CAM users and nonusers from within the California Cancer Registry database Abbreviation: PAM+V, Pan-Asian medicine plus vitamins; CAM, complementary and alternative medicine.