What are the important differences that distinguish the management of a cancer-related pathologic fracture from the treatment of ordinary fractures?

A pathological fracture is one in which breaks in the bone were caused by an underlying disease. Examples of pathological fractures include those caused by cancer (see Figure 1), osteoporosis, or other bone diseases.

Figure 1: Pathological fracture of the humerus in a patient with metastasis of renal cell carcinoma, from Wikipedia

Most occurrences of cancer in bone are metastatic lesions, that is, cancer that has spread from a different location, such as lung or breast, and traveled to the bone in question. (Primary bone tumors, such as osteogenic sarcoma, are comparatively rare.)

The major difference between treating cancer-related pathologic fractures and treating ordinary fractures is based on the loss of skeletal integrity and strength caused by the presence of cancerous tissue in bone.

Pathologic fractures are typically low energy (as it does not take much force to break weak bone). The fracture pattern is also often different: pathological fractures have a transverse fracture pattern, while higher energy fractures are typically spiral or comminuted.

Further, skeletal metastases from carcinomas are typically osteolytic: the tumor cells in the bone increase osteoclast activity, eroding the bone and causing pain, fractures, and sometimes hypercalcemia. Lesions can also be osteoblastic (characterized by increased bone formation, as seen with metastases from prostate cancer) or mixed osteoblastic/osteolytic. Osteoblastic lesions have abnormal bone architecture: thus, these bones are prone to fracture, even though one might say “more bone is present.”

Finally, the management of cancer-related fractures often involves coordination with medical subspecialties that will also treat the patient. Treatment of cancer-related pathologic fracture takes into consideration the nature of the specific type of cancer, the chemotherapy or radiation therapies available for adjuvant treatment, the need for further diagnostic evaluation to diagnose the source of disease, as well as the wishes of patients in palliative treatment (which may differ significantly from how a fracture would ‘normally’ be treated’).

Specific Difference in Management

Treatment of pathologic fractures draws on many of the techniques that have been developed for the treatment of ordinary fractures in normal bone. Nonetheless, there are important differences that distinguish the management of a cancer-related pathologic fracture from the treatment of ordinary fractures, including the following:

1. Consideration of prognosis

Patients with a very short life expectancy may prefer not to have their fractures treated beyond palliative care. It is essential to talk with the patient, the family and the other oncologic providers regarding the patient’s wishes and prognosis. Fracture fixation has the benefit of markedly reducing pain, and thus is often performed even in patients with advanced cancers. Shared decision making is key.

2. Need for diagnostic work up

Patients with pathologic fractures may need a more extensive diagnostic work up, including bone scans to exclude additional lesions and possibly a tissue biopsy to confirm the diagnosis. Even if there is a known primary, it is possible that a lesion might represent new, second cancer (especially if there is a lone "solitary" lesion in the bone). Primary versus metastatic disease are treated very differently. In the case of a solitary lesion, it might be necessary to perform a biopsy. It is also important to get full length films of the involved bone. It is especially disastrous to fix one lesion with a plate or rod that ends right above a new lesion. (There are at least three reasons this is very, very bad. Try to deduce them.)

3. Need for pre-operative treatment

Patients with metastatic disease will frequently be on chemotherapy protocols for their primary diagnosis. The timing and selection of any surgical procedures should consider the effect of chemotherapy on wound healing and immunosuppression. Also, radiation or tumor embolization might be needed. (Metastatic renal cell carcinoma, for example, is notorious for its tremendous vascularity, and without preoperative embolization, surgery is especially difficult and dangerous.)

4. Expeditious but not hasty surgery

The timing of surgery and the care needed before and after must be coordinated with medical and radiation oncologists, among other providers. The patient might need preoperative chemotherapy, and surgery might need to be delayed until low blood counts have rebounded.

5. Altered surgical strategies

Normal bone healing processes are impeded in pathologic fracture (due to local and systemic factors) and routine healing cannot be relied open. Also, because a key part of many cancer surgeries is to remove the cancer from the bone, surgery may create large defects. Taken together, there may be a need for much more bone cement than usual.

Also, athough it is ordinarily beneficial to try a simple method initially, reserving extensive treatment only if the simple attempts fails, patients with pathologic fractures might benefit from more definitive, albeit larger, surgeries at the outset. For example, instead of trying to fix a fracture of the distal femur, as would be done ordinarily, a pathological fracture might be treated with prosthetic knee replacement as the index procedure. As Dr Richard D Lackman, a noted orthopaedic oncologist counsels, "It is often preferable to do the last operation first."

6. Need for post-operative treatment

Note that surgical treatment of the fracture typically does not eliminate all tumor cells. Thus, post-operatively, radiation is typically is needed to control the local disease and minimize the chance of recurrence. (Some tumors, such as lung cancers and renal cell cancers are less sensitive to radiation, and have to followed more closely.)

Additional Points to Consider

If a patient has a bone lesion, it may be wise to “fix” the bone before it fractures – so-called prophylactic fixation. Musculoskeletal oncologists will typically prophylactically treat impending fractures with skeletal fixation (with or without cement) before an actual break in the bone happens. Large and painful cortical lesions in the leg (especially near the hip) are at high risk of breaking, and surgery performed while the bone is still in continuity is much easier for both the patient and surgeon alike (see Figure 2). The risk of fracture can be estimated by considering the amount of cortical destruction; the lytic or blastic nature of the lesion; the location of the lesion; and the presence of pain.

Figure 2: an impeding fracture of the humerus is shown in the image to the left (arrow). This was prophylactically fixed with a locked nail, as shown to the right. (Courtesy of Treatment of Pathological Humerus-Shaft Tumoral Fractures with Rigid Static Interlocking Intramedullary Nail-22 Years of Experience. Rev. bras. ortop. [online]. 2019, vol.54, n.2 https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-36162019000200149)
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