This study aimed to summarize the immediate operative and short-term efficacy and safety outcomes of percutaneous cementoplasty for pelvic metastases

Bone metastasis (BM) is the major cause of morbidity in patients with cancer. After lungs and liver, bone is the third most common site of metastatic disease. Prostate and breast cancers are responsible for the majority of bone metastases (up to 70%), followed by thyroid, lung, urinary bladder, and renal cancers, and finally melanoma. The incidence of bone metastasis is approximately 100,000 new cases per year in the united states and is increasing. Bone metastasis could result in skeletal-related events, including pain, pathological fracture, hypercalcemia, and nerve and visceral compression, which seriously affect the quality of life (QoL) of cancer patients. Bone metastases can be classified as osteolytic (osteoclast-mediated bone resorption), osteoblastic (osteoblast-mediated bone deposition), or mixed.

Fifty percent of the pain symptoms experienced by patients with cancer originate from BM. Tumor extension to neural structures, can cause a pain that may be radicular (exacerbated by percussion or palpation) and/or mechanical (exacerbated by movement). In advanced cases, pain can become intolerable and refractory to conventional therapies, resulting in walking disability, psychological and functional impact, and significant worsening of the QoL.

The effectiveness of surgery for bone metastasis in advanced cancer patients is limited to improvement of patients' quality of life. In most of these patients, complete resection or extended curettage of the bone metastasis with major reconstruction is often not feasible due to their poor general condition and accompanying other metastases. For some types of these bone metastases, surgical resection can lead to the stripping of the surrounding soft tissue and muscle attachment and addressing bone defects, causing more intraoperative bleeding, prolonged healing time, and increase the risk of wound complications, which in turn result in a longer recovery time for patients who usually have a limited life expectancy. Therefore, less invasive procedures, including percutaneous ablation (microwave ablation, radiofrequency ablation, cryoablation, and high-energy ultrasound) and/or bone cement [polymethylmethacrylate (PMMA)] injection, have become possible options. This is especially true for pelvic metastatic lesions because the surgery is particularly burdensome.

In addition, life expectancy of patients with metastatic bone disease is the most important factor in the decision making for surgical and/or medical treatment. A short life expectancy is in favor of the use of less invasive procedures, that have lower complication rates and shorter rehabilitation times. In these situations, interventional radiology procedures play an important either primary or complementary role in the management of bone metastases, especially in terms of palliation of pain, improvement of ambulation problems and treatment of fractures. This is because short life expectancies, more often, require palliative rather than curative regimens and make rapid pain relief to become a priority.

Aim of the study This study aimed to summarize the immediate operative and short-term efficacy and safety outcomes of percutaneous cementoplasty for pelvic metastases.

Materials and methods

Target Patients:

The study will include 20 patients with advanced cancer fulfilling the inclusion criteria and giving an informed consent to the study protocol (a single arm).

The following data will be collected from all patients:

1. Age at the time of the procedure

2. Gender

3. Primary cancer

4. Presence of lung metastasis

5. Presence of peritoneal metastasis

6. From the total bone scan:

   1. Unilateral or bilateral pelvic bone metastasis
   2. Solitary or oligometastasis (less than three sites) or multimetastasis ( 3 sites or more).
   3. Presence or absence of spine metastasis
   4. Presence or absence of lower limb metastasis

7. Previous surgery for cancer (site of the operation; pelviabdominal, lower limbs, spine, chest, brain)

8. Chemotherapy (preoperative, postoperative or both)

9. Radiotherapy (preoperative, postoperative or both)

Procedure:

The procedure will be performed under either spinal or general anesthesia. The patient will be placed in the lateral decubitus position with the surgical side up. The needle entry point will be adjusted with a fluoroscopic guide near the point 10 cm posterior to the anterior superior iliac spine. The skin and bone will be punctured by a 11-gauge needle. At least 2 or 3 different routes to the lesion will be established, and one needle will remain empty to allow decompression if possible.

The detailed procedure is described in the intervention section below. During the injection of PMMA, the anesthesiologist carefully will monitor the change in blood pressure and pulse rate, given the known toxicity of bone cement. The injected dose will vary according to the number of metastatic sites injected and their sizes.

All patients who has no contraindication to anticoagulation will be given (enoxaparin 40-60 mg per day) from 1 day before the procedure until ambulation was resumed for deep vein thrombosis prophylaxis.

The following procedural data will be collected:

1. Total cement amount
2. Injection needle number
3. Injection site number
4. Injected sites (Iliac bone or crest, acetabulum, ischium, pubic)
5. Duration of the procedure (in minutes)
6. Type of anesthesia used
7. If any other operation is performed concomitantly (nominate).

Outcome measures:

Primary outcome: is pain reduction:

Secondary outcomes: are

I- Gait function:

1. Gait status will be recorded pre and post operative
2. Gate function change II- Complications of the procedure (if more than one complication occurred in the same patient, all complications will be recorded)

A. Local:

1- Extraosseous bone leakage 2- Pathological fracture of the pelvic bones B. Systemic

1. Mortality
2. Pulmonary embolism
3. Bone cement implantation syndrome (BCIS):

Follow-up outcomes: at one month and 3 months

1. Mortality
2. Pain relapse (NRS score)
3. Gait relapse
4. Pathological fracture in the pelvic bones at the treated sites (by bone window CT).

Inclusion Criteria:

1. refractory pain and/or gait disturbance caused by pelvic bone metastasis, did not respond to conservative treatment.
2. osteolytic lesion (in predominance) suitable for the pain.
3. limited life expectancy (less than 3 years) or stopping medical treatment

Exclusion Criteria:

There are no absolute contraindications for the procedure; however, the relative contraindications are:

1. patients in poor condition with an expected survival period of less than 3 months.
2. patients with stable course, with long life expectancy (more than 3 years) or those considered candidates for major pelvic surgery including tumor removal and hip arthroplasty.
3. presence of bone destruction with soft tissue mass contaminating important organs, nerves and blood vessels (improvement is not expected).
4. Patients refusing to give a written consent to the study protocol.