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Soy-rich Diet for Preventing Chronic Pain After Breast Cancer Surgery

Phase 2
21 Years
Not Enrolling
Pain, Chronic Disease, Breast Cancer

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Trial Information

Soy-rich Diet for Preventing Chronic Pain After Breast Cancer Surgery

Preclinical studies indicate that soy consumption suppresses the development of pain
behavior and hyperalgesia following nerve injury. The pain-suppressing properties of soy
protein have been shown to be predominately the result of soy pre-operative consumption.

This is a randomized, double blind, placebo-controlled clinical trial for women diagnosed
with breast cancer and scheduled to undergo breast cancer surgery. The trial will comprise
two phases: 1. A 2-week preoperative dietary manipulation phase, and 2. A one-year
postoperative follow up period. In the first phase eligible candidates will undergo a basic
dietary evaluation followed by stratification into 4 study groups, based on their pre-vs.
postmenopausal status and the planned type of surgery, i.e., formal mastectomy vs.
breast-conserving surgery. Women in each group will be randomized to receive either powdered
soy protein in the experimental group or milk protein in the control group. During the
second, post-surgical phase women will resume their normal diet. If shown to be beneficial,
this simple dietary manipulation may prevent one of the most severe sequelae of breast

Inclusion Criteria:

- Women diagnosed with breast cancer and scheduled for elective breast cancer surgery
(excluding breast biopsy) with axillary lymph node dissection (total and/or sentinel
node excision).

- Women who are 21 years or older.

Exclusion Criteria:

- History of significant heart, gastro-intestinal, liver or kidney disease.

- Use of the anticoagulant, warfarin or Coumadin.

- Malabsorption of any kind.

- Diagnosed lactase deficiency.

- Known allergy to any of the tested dietary products.

- Basic daily consumption of soy protein in quantities exceeding 10 g/day.

- Women who are strict vegetarians (i.e. no animal derived dietary sources).

- The use of the following narcotics or adjuvant pharmacotherapy: opioids,
anticonvulsants, antidepressants and steroids (except antidepressant use specifically
for depression).

- Tumour size (if known) > 3cm(i.e. size before pre-operative chemotherapy, if

- Locally advanced breast cancer.

- Inflammatory breast cancer.

- Paget's disease of the breast with palpable mass.

- Suspected metastasis.

- Suspected micrometastasis.

- Previous breast surgery of any kind (except needle biopsy).

- The need for bilateral breast surgery.

- The existence of other known cancer, including metastasis, either in the other breast
or elsewhere.

- Previous or current endocrine cancer therapy (e.g. selective estrogen receptor
modulators, aromatase inhibitor).

- Body mass index (BMI) > 35.

Type of Study:


Study Design:

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Prevention

Outcome Measure:

Number of women in both arms with any pain of any type in operated breast or its vicinity

Outcome Time Frame:

12 months post-surgery

Safety Issue:


Principal Investigator

Yoram Shir, MD

Investigator Role:

Principal Investigator

Investigator Affiliation:

McGill University Health Center


Canada: Health Canada

Study ID:




Start Date:

March 2010

Completion Date:

March 2013

Related Keywords:

  • Pain
  • Chronic Disease
  • Breast Cancer
  • soy protein
  • diet
  • Breast Neoplasms
  • Chronic Disease