This study will evaluate whether a short nutritional intervention before surgery can improve recovery in patients with bone and soft tissue sarcomas.

Patients with these tumors often have a higher risk of poor nutrition and loss of muscle mass. These problems may increase the risk of complications after major orthopedic surgery.

Participants will be randomly assigned to one of two groups. One group will receive a special oral nutritional supplement twice daily before surgery, in addition to standard care. The other group will receive standard care without the preoperative nutritional supplement.

The main aim of the study is to compare the rate of clinically relevant postoperative complications within 30 days after surgery. The study will also evaluate changes in muscle mass on CT scans, blood markers of nutrition and inflammation, nutritional risk, functional status, length of hospital stay, and tolerance of the nutritional supplement.

Patients with bone and soft tissue sarcomas often require planned major orthopedic surgery as part of their treatment. These operations may include wide tumor resection and, in some cases, complex reconstruction of the affected limb or anatomical region. Because of the extent of surgery and the underlying oncologic disease, these patients may be at increased risk of postoperative complications, impaired wound healing, longer hospitalization, and slower functional recovery.

Nutritional status is an important factor that may influence surgical outcomes. Patients with sarcoma may develop malnutrition or reduced skeletal muscle mass due to the tumor itself, cancer-related systemic inflammation, decreased physical activity, reduced food intake, or previous oncologic treatment. Sarcopenia and poor nutritional reserve may decrease the patient's ability to tolerate major surgery and may contribute to a higher risk of postoperative morbidity.

Preoperative nutritional optimization is recommended in several areas of oncologic surgery, but evidence specifically focused on patients with bone and soft tissue sarcomas remains limited. In this population, there is no clear consensus regarding the optimal nutritional strategy, timing, or expected clinical benefit of short-term preoperative nutritional support. This creates a need for prospective data in real-world sarcoma care.

This prospective, randomized, controlled study will evaluate whether a standardized preoperative immunomodulatory nutritional intervention can improve postoperative outcomes in adult patients with histologically confirmed bone or soft tissue sarcoma who are scheduled for elective orthopedic tumor resection.

Eligible participants will be randomized to one of two study groups. Patients in the intervention group will receive standard care together with preoperative oral immunomodulatory nutritional support before the planned surgery. Patients in the control group will receive standard care without additional preoperative nutritional supplementation. The intervention will be carried out in the home setting during the preoperative period, reflecting routine clinical practice.

Patients will undergo nutritional assessment by a clinical nutrition therapist during the diagnostic and preoperative treatment pathway. If sarcoma is confirmed and the patient is indicated for planned orthopedic resection, the nutritional intervention will be prescribed for home use in the intervention group. At admission for surgery, adherence to the supplement and tolerance of the nutritional intervention will be assessed.

The primary objective of the study is to determine whether preoperative immunomodulatory nutrition reduces the occurrence of clinically relevant postoperative complications within 30 days after orthopedic resection. Complications will be evaluated using a standardized classification system and assessed through blinded review of medical records.

Secondary objectives will assess several aspects of perioperative recovery and nutritional status. These include changes in skeletal muscle mass using CT-based body composition analysis, laboratory markers related to nutrition and systemic inflammation, baseline nutritional risk, preoperative functional status, length of hospital stay, and the feasibility of the intervention based on adherence and tolerance.

The study will use CT scans performed as part of standard oncologic staging and restaging to evaluate changes in muscle mass. This approach allows assessment of sarcopenia without adding imaging procedures beyond routine clinical care. Laboratory parameters and clinical assessments will also be collected within the standard perioperative pathway whenever possible.

The study is designed to reflect real-world treatment conditions in a tertiary sarcoma center. The results may help clarify whether short-term preoperative immunonutrition is feasible and clinically useful in patients with bone and soft tissue sarcomas undergoing major orthopedic surgery. The findings may also support future development of perioperative nutritional protocols for this high-risk patient population.

Inclusion Criteria:

• Participants must meet all of the following criteria:
• Adult patients aged 18 years or older.
• Histologically confirmed bone sarcoma or soft tissue sarcoma.
• Localized or oligometastatic disease.
• Indicated for planned orthopedic tumor resection.
• Preoperative interval allowing administration of the nutritional intervention for at least 7 days, with 14 days preferred when clinically feasible.
• Ability to receive oral nutritional supplementation.
• Signed informed consent for participation in the study.

Exclusion Criteria:

• Participants will be excluded if any of the following criteria are present:
• Indication for urgent surgery.
• Disseminated disease with more than five metastases.
• Ongoing parenteral nutrition before study enrollment.
• Inability to receive oral intake.
• Severe hepatic failure.
• Severe renal failure.