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Is it safe to use Soy Isoflavone Genistein along with Chemotherapy for Metastatic Colorectal Cancer?

Feb 24, 2020


A clinical study has demonstrated that it is safe to use the soy isoflavone Genistein supplement along with the combination chemotherapy FOLFOX for the treatment of metastatic colorectal cancer. Combining Genistein with chemotherapy has the potential for improving the treatment outcome.

Metastatic Colorectal Cancer (mCRC) has poor prognosis with a 2-year survival being less than 40% and a 5-year survival being less than 10%, despite the very aggressive combination chemotherapy treatment options. (AJCC Cancer Staging Handbook, 8th Edn) The standard of care treatment for mCRC is a combination of multiple cytotoxic chemotherapy drugs: 5-Fluorouracil along with a platinum drug Oxaliplatin, with or without the antiangiogenic (inhibits formation of blood vessels to the tumor) agent Bevacizumab (Avastin).

Genistein Use in Colorectal Cancer

Genistein Use in Colorectal Cancer

Multiple studies have shown an association of lower risk of colorectal cancers in east Asian populations that eat a Soy-rich diet. There are many preclinical experimental studies that have demonstrated the anti-cancer properties of the soy isoflavone Genistein, and its ability to reduce chemotherapy resistance in cancer cells. Hence, researchers at the Icahn School of Medicine at Mount Sinai, in New York, tested the safety and efficacy of using soy isoflavone Genistein along with the standard of care combination chemotherapy in a prospective clinical study in metastatic colorectal cancer patients. (NCT01985763) (Pintova S et al, Cancer Chemotherapy & Pharmacol., 2019)

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Details of the Clinical Study

  • There were 13 patients with mCRC with no prior treatment who were treated with the combination of FOLFOX and Genistein (N=10) and FOLFOX + Bevacizumab + Genistein (N=3)
  • Primary endpoint of the study was to assess safety and tolerability of using Genistein with the combination chemotherapy. The secondary endpoint was to assess the best overall response (BOR) after 6 cycles of chemotherapy.
  • Genistein at a dose of 60 mg/day, was given orally for 7 days every 2 weeks, beginning 4 days prior to the chemo and continuing through days 1-3 of chemo infusion. This allowed the researchers to assess the side-effects with Genistein alone and in the presence of chemo.

Results of the Clinical Study

  • The combination of Genistein with chemotherapy was found to be safe and tolerable.
  • Adverse events reported with Genistein alone were very mild, such as headache, nausea and hot flashes.
  • Adverse events reported when Genistein was given along with the chemotherapy were related to the chemotherapy side-effects, such as neuropathy, fatigue, diarrhea, however, none of the patients experienced a very severe grade 4 adverse event.
  • There was an improvement in best overall response (BOR) in these mCRC patients taking the chemotherapy along with Genistein, when compared to those reported for the chemotherapy treatment alone in earlier studies. BOR was 61.5% in this study vs. 38-49% in previous studies with the same chemotherapy treatments. (Saltz LB et al, J Clin Oncol, 2008)
  • Even the progression free survival metric, that indicates the amount of time that the tumor has not progressed with the treatment, was a median of 11.5 months with Genistein combination vs. 8 months for chemotherapy alone based on a prior study. (Saltz LB et al, J Clin Oncol., 2008)

This study, although on a very small number of patients, demonstrates that using soy isoflavone Genistein supplement along with the combination chemotherapy was safe and did not increase the toxicity of the chemotherapy in Colorectal Cancer. In addition, using Genistein in combination with FOLFOX has the potential to improve the treatment efficacy and possibly reduce the side-effects of the chemotherapy. These findings, although promising, will need to be evaluated and confirmed in larger clinical studies.

Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer. Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.