The Effects of Soy Protein on Post-thoracotomy Pain
The Effects of Soy Protein on Post-thoracotomy Pain
This study seeks to determine whether soy protein supplements reduce the pain that often
 occurs following surgery for a lung tumor. Patients are randomized to receive either soy
 protein or milk protein prior to and following a thoracotomy for a lung tumor. We are
 especially interested in pain severity and pain medication use following surgery and will
 measure function and quality of life.
Preclinical studies indicate that soy-containing diets suppress the development of pain
 behaviors and hyperalgesia seen following nerve injury and recent data indicate a similar
 protective effect of a diet high in soy protein in inflammatory and bone cancer pain models.
 These studies further indicate that soy exposure is only protective when administered in the
 period immediately preceding injury. Very few studies have directly studied the effects of
 soy-containing diets on pain sensitivity in humans, but one recent randomized clinical trial
 suggests that dietary soy supplementation may reduce pain due to osteoarthritis. The proposed
 study will examine whether a soy protein supplement reduces the pain commonly experienced
 following thoracotomy for lung surgery. This is a useful clinical model for studying the
 effects of soy protein supplementation on pain because the pain associated with surgery is
 quite severe and is one of the greatest concerns patients have about undergoing surgery. The
 growing recognition that greater acute pain leads to persistent pain following tissue healing
 underscores the importance of identifying viable strategies, including both
 non-pharmacological as well as pharmacological, for reducing the acute pain associated with
 surgery. Using a 2 group (soy protein supplementation vs. matched milk placebo
 supplementation) design, patients undergoing elective major open thoracotomy for
 segmentectomy, lobectomy, or bilobectomy will be randomly assigned to one of these two
 treatment groups. Patients will begin taking the soy/placebo supplement 2-3 days prior to
 thoracotomy and continue daily consumption of the supplement for an additional period
 following surgery. The feasibility/pilot study will examine the effects of soy
 supplementation on outcome measures during three post-operative time periods: 1) the
 immediate post-operative period; 2) during 2-12 weeks following surgery; and 3) during 14-24
 weeks following surgery. Pain is the primary outcome domain of interest in this pilot study
 and measures will include pain severity ratings and pain medication use. Function and quality
 of life are the secondary outcome domains of interest and measures will include pain-related
 interference with daily activities, sleep, and health-related quality of life. Outcome
 measures will be collected bi-weekly throughout the study. The study aims to determine the
 feasibility and acceptability of soy supplementation in the period surrounding thoracotomy,
 determine level of adherence to soy supplementation over the 6-month period of follow-up, and
 estimate the effect size of soy supplementation relative to placebo in reducing significant
 pain following thoracotomy. The proposed study will provide the necessary groundwork to move
 towards such a larger randomized trial to evaluate the pain-reducing effects of soy protein
 supplementation following thoracotomy.
Inclusion criteria: 1) undergoing major elective thoracotomy through a classic incision,
 including segmentectomy, lobectomy, or wedge resection, 2) for women, a negative mammogram
 within the past year; 3) for women using oral contraceptives or hormone replacement
 therapy, the agreement to hold steady dosing of these medications for the duration of the
 study; and 4) ability to comprehend the consent information and to complete all study
 assessments.

 Exclusion criteria: 1) age less than 18 years, 2) current alcohol or substance
 abuse/dependence; 3) delirium, dementia, or cognitive impairment (MMSE < 24; (23)); 4) use
 of analgesics (other than aspirin or non-steroidal anti-inflammatories) for a condition
 other than the reason for surgery; 5) milk or soy allergy; 6) lactose intolerance; 7)
 pre-operative chest pain; 8) women with a history of breast cancer; or 9) [use of an
 antibiotic within 3 months prior to surgery.