The Effect of Soy Protein on Post- Breast Cancer Surgery Pain

Overview

The incidence of chronic pain after breast cancer surgery (CPBCS) is high in women diagnosed with breast cancer. Similar to other chronic postoperative pain conditions, existing treatments for CPBCS do not always work. Adopting the concept of using pain relieving measures prior to surgery rather than after it, may lead to decreased postoperative pain levels. Soy has been shown to have pain-relieving properties and may reduce the risk for developing chronic post-surgical pain. The purpose of this study is to determine the effects of adding soy protein to the diet before surgery on the development of chronic pain.

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 cancer.