The aim of this study is to find which is the best nutritional strategy in cancer patients undergoing abdominal surgery regarding postoperative complications.

There is a controversy regarding the timing of initiation of parenteral nutrition in cancer patients undergoing abdominal surgery in whom caloric targets cannot be met by enteral nutrition alone.

This is a randomized and controlled trial comparing early initiation with late initiation of parenteral nutrition.

Early-initiation group: patients will be randomized to initiate parenteral nutrition in the 2nd day after surgery.

Late-initiation group: patients will be randomized to initiate parenteral nutrition in the 7th day after surgery.

Calculations regarding the caloric goal included protein energy and were based on corrected ideal body weight, age and sex. When oral or enteral nutrition covered 80% of the calculated caloric goal, parenteral nutrition was reduced and progressively stopped.

Inclusion Criteria:

• Older than 18 years
• Laparotomy for abdominal cancer surgery: urological, gynecological, digestive, abdominal sarcomas and melanomas, lymphomas and abdominal vascular.
• Informed consent form signed by the patient or legal guardian.

Exclusion Criteria:

• Reoperation within one year from the previous surgery. using previously parenteral nutrition.
• Participation in another research protocol.