HOLLYWOOD, FL—New guidelines that offer treatment algorithms for two relatively rare cancers—chordoma and giant cell tumors of the bone—were presented here at the National Comprehensive Cancer Network Annual Conference.
“The important thing to remember about chordoma is that if you suspect a patients has this bone cancer, you must refer the patient to a center of excellence, because even performing a biopsy can compromise the patient's survival,” said J. Sybil Biermann, MD, Professor and Medical Director of the Sarcoma Program at the University of Michigan Comprehensive Cancer Center and Chair of NCCN's Bone Cancer Guideline Writing Committee.
Although those usually benign tumors are generally considered to be in the realm of orthopedic surgeons, the committee decided to include them in the guidelines because there is still a small (about 2%) chance that the tumors can become malignant, she explained.
“Bone cancer is not very common—there are only about 2,500 cases a year in the United States. The most common are osteosarcomas—about 35 percent of that total—followed by Ewing's sarcoma—15 percent of the total—and chondrosarcoma—about 25 to 30 percent of the total. There are maybe 300 chordoma cases a year in the United States. About 60 percent of chordomas occur in the sacrum, about 25 percent in the skull base, and the remainder are up and down the mobile spine.
“All patients should be evaluated and treated by a multidisciplinary team with expertise in the management of chordoma,” Biermann emphasized. The team should include a musculoskeletal oncologist, a bone pathologist, a medical or pediatric oncologist, a radiation oncologist, and a musculoskeletal radiologist. The specialists on that team include a thoracic surgeon, a plastic surgeon, an interventional radiologist, a physiatrist, a vascular/general surgeon, a neurosurgeon, and other surgical specialists as needed.
“The best chance we have to cure a chordoma is the first surgery that is performed in a center with experience with these tumors,” Biermann said, noting that when doctors unfamiliar with chordomas attempt to perform a biopsy on these patients they can often make things worse.
“A physician in doing a physical will feel a mass and perform a transrectal biopsy of the chordoma,” she said. “What that does, though, unfortunately, is create surgical spread of the disease into the rectum.”
In turn that can require removal of part of the intestine and a need for colostomy. “Biopsy misadventures that can occur in tumors in general and in chordomas in general are very important. Any time a chordoma is suspected, the patient should be referred to a multidisciplinary team.”
Because biopsy misadventure occurs as much as 18 percent of the time, the biopsy should be performed at the same center and by the same surgeon who does the main tumor resection, she said.
The first step is adequate imaging of the primary site of the tumor with x-ray, MRI, or computed tomography and a screening MRI of the spinal axis. A CT of the chest, spine, and pelvis should be performed. and a PET scan can be considered; if the PET scan is negative a bone scan is another option.
“These tumors can be multi-focal and if so, more extensive imaging is required,” she said. “This is one of those diseases that often has an 11-month delay in diagnosis because symptoms of sacral pain and back pain mimic other musculoskeletal symptoms.
“These tumors are malignant and they will invariably recur if they are not completely extricated. The guidelines call for chordomas of the sacrococcygeal and mobile spine to be treated by wide resection, with or without radiation. Radiation should be considered if the tumors cannot be resected. If there are positive surgical margins, radiation can be considered. Larger tumors that extend outside compartments are also possible targets for radiation after surgery.”
For lesions of the skull base, intralesional excision is recommended, Biermann said. “Radiation can be considered if the lesions are not considered to be resectable. Follow-up MRI is suggested to assess the adequacy of the resection, and if there are positive margins or larger tumors, radiation and re-resection can be considered.
“Most centers would consider that negative margins are sufficient and would therefore not proceed with radiation, unless there were other reasons.” Follow-up MRIs are not often done with most cancer treatments, but in chordomas of the skull base it is critically important.
Biermann said that after resection, patients should undergo surveillance every six months for five years and then annually, including annual cross-section abdominal imaging. If there is recurrence surgical excision, radiation and systemic therapy are options. “Chordomas can be very slow growing tumors and there are a lot of late recurrences,” she cautioned.
Giant Cell Bone Tumors: Diagnosis Typically After Long Period of Pain
Giant cell tumor of the bone usually presents after a long course of pain caused by the tumor growth, which can also impact mechanical functioning, Biermann said. The disease occurs more often in mature individuals, around the age of 30.
In the past, treatment was performed almost exclusively by surgeons, she noted. But because the surgery resulted in the need for prosthetics that have a finite time for usefulness, treatment has extended to a team approach.
She illustrated that doctors now fenestrate the tumor, creating a large window in the bone to visualize the extent of the tumor. The use of curettage and high speed burrs removes traces of the tumor.
“Our struggle is to get out as much of the tumor as possible but still leave the joint intact. When we get recurrences it usually is at the joint because that is the part where we have the most difficulty. The cavities are then filed with bone grafts and other adjuvants.”
The use of high speed burrs and various chemical, thermal, or other adjuvants has reduced recurrence rates from around 50 percent with surgery alone to as low as 10 to 29 percent, depending on the series considered, she said. “When recurrences occur it is problematic because it generally means destroying the joint and fitting the patient with a prosthesis that is unlikely to be durable for life.”
When giant cell tumor of the bone occurs in areas like the sacrum, the treatment is more difficult because use of adjuvants is limited due to the location of blood vessels and nerves.
Although the risk of metastasis is only two percent, the disease requires special treatment, requiring a multidisciplinary approach, including surgery, imaging, use of adjuvants, and the increasing use of denosumab in therapy, Biermann said.
Advent of Denosumab
“Denosumab is one of the things that is changing my practice the most because it gives us better options for these patients with tumors of the bone. Patients with giant cell tumor of the bone often see multiple practitioners before they are diagnosed, so we often see a lot of bone destruction before they are actually and accurately diagnosed.” The use of denosumab in some patients can restore enough bone to make joint-sparing surgery feasible.
“Preventing pathologic fractures is very important in these patients,” she said. “Use of denosumab allows us to restore some of the structural stability, perform smaller operations, and some patients can be spared surgery completely.”
The new guidelines call for imaging of the suspicious site with x-rays and magnetic resonance imaging, with or without CT and biopsy to confirm diagnosis. If the tumor is localized, excision is recommended.
If the extent of the tumor makes resection impossible without unacceptable morbidity, then the choices in the treatment algorithm are serial embolization—particularly for tumors of the pelvis—denosumab, interferon, pegylated interferon, or radiation until disease stabilization and excision becomes possible. In cases where the disease remains unresectable, denosumab treatment should be continued.
Radiation, while effective in giant cell tumor of the bone, is also associated with adverse events, and there have been reports of transformation of the disease to a malignant state. Therefore, she, said, “Radiation should be considered a last resort for treatment of giant cell tumor if the bone.”
If the disease is metastatic at presentation the choices are resection and then treatment as with localized disease. Doctors should also consider excision of metastases, but if that is not possible, resectable, clinicians can consider use of denosumab, interferon, radiotherapy or observation as options.
Surveillance chest imaging for these patients should be performed every six months for two years after definitive treatment, and then annually, the guidelines suggest.