Protein synthesis dynamics in human gastrointestinal malignancies

Area of Science:

• Oncology
• Nutritional Science
• Metabolic Research

Background:

• Cancer and its treatments cause malnutrition, necessitating nutritional support.
• Intravenous hyperalimentation (IVH) is used for nutritional support but raises concerns about enhancing tumor growth.

Purpose of the Study:

• To investigate the effect of preoperative dietary regimens on tumor and gastrointestinal tissue protein synthesis rates in cancer patients.
• To determine if IVH enhances tumor protein synthesis compared to oral diets.

Main Methods:

• Twenty-five gastrointestinal cancer patients received either ad libitum oral diet or IVH preoperatively.
• Stable isotope tracer (N-glycine) was used to measure in vivo tissue fractional protein synthesis rates (PSRs) from operative specimens.

Main Results:

• Tumors in IVH-fed patients showed no significant difference in protein synthesis rates (14.2%/day) compared to orally fed patients (15.1%/day).
• Tumor PSRs positively correlated with the PSRs of their originating tissues (r = + 0.708, P < 0.005).
• IVH maintained gut protein synthesis rates comparable to oral diets.

Conclusions:

• Parenteral nutritional support (IVH) does not increase protein synthesis rates in cancer patients beyond levels seen with regular oral diets.
• These findings suggest that optimal nutritional support for cancer patients might be possible without inadvertently stimulating tumor growth.