Metachronous presentation of metastasis from renal cell carcinoma: evaluation and management of spinal metastasis.

Introduction

Surgical treatment of metastatic cancer in the appendicular skeleton is well supported in the literature. Straightforward indications include pathologic fracture and impending pathologic fracture.1,2 More controversial indications for operative treatment exist regarding resection or en-bloc removal for solitary metastases or other painful metastases.3 Overall, surgical decision making must be tempered by the patient's overall performance status (ECOG, Eastern Cooperative Oncology Group), tumor type (with relation to expected survival and relative radiosensitivity) and the patient's perceived ability to recover from surgery.A,4

As controversial as surgical indications are in the appendicular skeleton, they are at times even more contentious in the axial skeleton. Issues such as established neurologic deficit as well as impending neurologic decline are compounded by uncertain criteria for stability and pathologic fracture. The purpose of this current report is to describe the unusual presentation of a symptomatic spinal metastasis in the setting of systemic disease, review the indications and treatment and then consider what was done using an “evidence-based medicine approach”.

Case Report

A 64-year-old woman was seen in surgical orthopedic oncologic consultation for a new metastasis to the right distal femur. She was originally diagnosed with renal cell carcinoma 8 years prior, with metastatic disease to her mediastinal lymph nodes discovered 5 years later but had been considered in a stable disease state on systemic therapy with a tyrosine kinase inhibitor. In addition to her femoral disease she had a several year history of low back pain and occasional radiating ipsilateral right lower extremity pain. Her femur showed a lytic metastasis of the distal femoral metastasis. This was treated with curettage, local adjuvant (hydrogen peroxide and electrocautery) and poly-methyl-methacrylate (PMMA) augmentation. Her back pain was treated nonoperatively at this time. Approximately 1 year later, the patient reported new pain in the left thigh associated with activity. A new technetium bone scan identified two distinct lesions in the left femur and an additional lesion in the left ischium. Options were discussed with the patient and it was decided to proceed with surgical treatment of the femoral lesion for a symptomatic metastasis and to address the ischial lesion at the same surgical setting.

The femoral lesions were treated with simple intramedullary nailing. The ischial lesion was embolized preoperatively and then treated with curettage and local adjuvant (hydrogen peroxide5 and electrocautery) followed by packing of the cavity with PMMA. Operative approach for the ischial lesion was a straight posterior approach as utilized for hamstring avulsion repairs. The sciatic nerve was identified and manipulation minimized. Postoperatively the patient had severe left-leg sciatic symptoms requiring escalating doses of narcotics and gabapentin therapy.

After several weeks of minimal improvement, the patient was given an L4/5 translaminar epidural steroid injection. This did provide her with moderate pain relief and allowed her to slowly wean her narcotic requirement. After a slow return of her left leg pain, a second injection was given 3 months later with similar but slightly less pain relief. This postoperative course was complicated by the patient also receiving radiation therapy to 3000 Gy to her ischium and left femur.

Six months following her last surgery the patient returned for an unscheduled visit with 2 weeks of crescendo low back pain and radiation down her bilateral posterior thighs. Noting the significant change in her pain without obvious inciting event, a new CT and MRI were ordered of her lumbar spine. These studies revealed a lytic lesion in her right L5 pedicle with expansion of the pedicle and right-sided nerve root impingement. Options were discussed with the patient including radiation therapy, embolization, surgical treatment and various combinations of the above. Based on her baseline degenerative lumbar spine problems, acute pain exacerbation, and the relatively poor radiation sensitivity of this tumor, it was decided to proceed with surgery.

Surgical intervention

Following preoperative embolization within 24 hours of planned surgery, we performed a wide posterior approach and placed pedicle screws bilaterally at L4 and S1 and unilaterally on the left side of L5. Inferior facetectomy of L4 was performed along with laminectomy of L5 to allow isolation of the L5 posterior elements and pedicle. At this point the tumor was excised in an intralesional manner. Gross total excision of the tumor was performed with resection of the entire pars, inferior articular facet, transverse process and pedicle down to the vertebral body of L5. Bleeding was well controlled due to a thorough preoperative embolization and a controlled and methodical tumor resection.

After local adjuvant neoplasia treatment with peroxide, electrocautery and a high speed diamond tip burr, the L4/5 and L5/S1 disks were removed and posterior lumbar interbody fusion was carried out with transforaminal interbody allograft cages, local autograft and cancellous allograft bone and posterolateral arthrodesis completed with decortication, bonegraft placement and placement of rods and crosslink. Meticulous wound closure with nonresorbable sutures, intended to be left in place for an extended time, was carried out. The patient's postoperative course was unremarkable. She did receive postoperative radiation therapy beginning at 3 weeks postoperatively. The patient had an unremarkable postoperative course, was off of narcotic pain medicines by the 2-week follow-up visit and has had durable pain relief of her baseline back pain and her lower extremity radicular symptoms with no evidence of tumor persistence or recurrence at short-term (6-month) follow-up.

Learning points

Patients with metastatic cancer should undergo scheduled surveillance staging studies relevant to their given disease. Timing intervals and choice of studies can be selected based on established guidelines such as the National Comprehensive Cancer Network.6

Surgical treatment of metastatic disease does not reliably provide a cure for patients in isolation. All patients should be managed by a multidisciplinary team which can include surgeons as well as medical oncologists and radiation oncologists. Metastatic disease represents a systemic disease and the only meaningful opportunity for a cure will necessitate systemic therapy which can include traditional cytotoxic agents as well as hormonal therapies or novel targeted chemotherapy agents (for instance tyrosine kinase inhibitors).

Each type of primary cancer has a unique natural history. Patients with certain tumors such as lung cancers have a typically short expected life span versus those whose tumors such as breast or renal cell which can have a much more indolent but progressive course.7,8,9 Any operation considered should include a thoughtful discussion with the patient regarding the expected recovery from the planned intervention in the context of their expected longevity. For a major intervention such as spine surgery, patient life expectancy less than 3 months has been considered a contraindication for spine surgery.

The radiosensitivity of the offending tumor is a very important variable. For example, patients with myeloma or lymphoma rarely require surgical intervention due to their response to chemotherapy and radiation therapy. Breast cancer is also frequently responsive to traditional external beam radiation therapy whereas renal cell carcinoma and melanoma are remarkably insensitive for the treatment of bulky disease.10

In terms of clinical progression a patient with an established cancer diagnosis deserves a low threshold for ordering advanced imaging studies with the onset of new or crescendo pain. This patient had confounding baseline low back pain and then experienced nonspecific exacerbation of radicular pain following surgical intervention for her tumor disease in another region. Listening to the patient and not relying on a negative result from a bone scan prompted the treating physician to order a new MRI when the character and severity of the pain changed.

The choice of surgical intervention is frequently challenging in these patients. Attempted en-bloc resection in the appendicular skeleton has been discussed extensively and does not convincingly result in a durable cure. Consideration can be given to this type of resection in the setting of solitary metastases.B,11 Unfortunately the likelihood of being able to achieve an en-bloc resection with true negative margin in the spine is low and the added risk is typically not justified by the expected benefit. Patients also almost uniformly get postoperative radiation therapy and this can also adversely affect fusion rate.12 The length of the reconstruction construct should be considered and a longer construct is typically a better option. Despite thoughtful interventions, local recurrence is more of the rule than the exception, with implications for possible future surgery in case of tumor recurrence. For example, in the present case the rods were left long caudally intentionally. The side-loading system utilized (Synthes USS, Synthes, Paoli, PA) in this case would allow the placement of iliac bolts with the current construct left intact and proximal extension also possible without extensive local re-exploration in a vascular, postirradiated bed.

Coronal MRI femur'07

Right femur postoperative

Sagittal MRI spine '07

Left ischial metastasis

Intraoperative left femur and ischium (patient in prone position)

Sagittal MRI spine '09

Para-sagittal MRI spine '09

CT with L5 metastasis

Postoperative spine lateral

Postoperative spine AP

Conclusion

The current gold standard regarding the surgical treatment of metastatic spine disease largely relies on a study by Patchell et al, which recommended direct decompressive surgery for non-myeloid spine tumors with epidural spinal cord compression and either neurologic deficit or impending compromise.C Unfortunately, this article didn't address disease manifestation at the root level. Our further resources are mainly limited to the natural (treated or untreated) history of cancers from a variety of different origins, anticipated responsiveness of these tumors to radiation therapy and guidelines regarding the pre-operative evaluation and selection of appropriate surgical candidates. Unfortunately this is a complex decision making process, without concrete answers in validated reference materials. This leads to individualized treatment approaches using multidisciplinary resources, including radiation and medical oncologists.