Primary bone cancer rare, difficult cancer to treat

Doctors advise


As cancers go, primary bone cancer is a comparatively rare disease, much less prevalent than other cancers such as melanoma, lung and breast. But it is among the toughest types of cancer to treat. More problematic, our bones are often attractive sites for more common metastatic cancers that have spread from other parts of the body.

There are fewer than 150 board-certified orthopedic oncologists in the United States – physician-surgeons with extra training in the particular diagnosis and treatment of bone cancer. We asked one of them, Dr. William Bowman of the UC San Diego Moores Cancer Center, to talk about the nature of bone cancer and current treatments.

Q: Over the last few decades, science and medicine have made measurable strides against some types of cancer and little or no progress against other types. How would you describe specific efforts to understand, treat and cure bone cancer? Are rates going up, down, static? Is the prognosis good, bad or unchanged?

A: First of all to understand bone cancer, one has to realize there are two basic types of bone cancer. There are cancers that arise primarily in the bone. These are called the primary bone tumors. There are also cancers that spread to the bone from another site. The rates of cure for primary bone cancers have improved dramatically in the past 30 years. However the rates of cure for secondary or metastatic bone cancer have not improved a great deal. There are new and better ways to manage cancer that spread secondarily to bone, but in the vast majority of situations metastatic or secondary bone cancer is not curable.

The most common cancers that spread to bone are breast, prostate, lung, thyroid and kidney. The rates of bone cancer are stable. The prognosis for primary bone cancer has improved dramatically since 1970 when the cure rate for osteosarcoma was less than 25 percent. The cure rate now approaches 70 percent. The prognosis for secondary or metastatic cancer has not improved in the last 30 years.

Q: Malignant tumors that originate in bone tissue are relatively rare, but cancers that spread to bones from elsewhere in the body are not. Is the reason for this known? Are bone tissues particularly hospitable to hosting secondary cancers?

A: Most primary malignant tumors of bone occur in adolescence or young adults. So it appears that age and growing bones have something to do with the development of primary malignant tumors. The actual cause is not known. Bone is a common location for metastasis. It is thought bone marrow provides a good environment for growth of cancer.

Q: What are the particular challenges of pediatric bone cancer? For example, does the fact that a child-patient is still growing make things more complicated than a similar orthopedic cancer in an adult?

A: In pediatric bone cancer, not only do you have to deal with removing the tumor surgically, but you must also plan how to manage a patient who will continue to grow. In recent years, we have developed an expandable prosthesis. Periodically another surgery is required to lengthen the operative leg. In a very young patient, he may have to have three or four surgeries to account for the limb length discrepancies. In very young patients under the age of 6 or 7, you may have to consider amputation.

Q: How are bone cancers typically treated? How has treatment changed over the years? Are there any new or dramatic therapeutic advances in the foreseeable future?

A: Most primary bone cancers occur in adolescence or young adults. The two most common childhood cancers in bone are osteosarcoma and Ewing’s sarcoma. Currently these tumors are treated with preoperative chemotherapy, followed by surgical resection of the cancer, reconstruction and then an additional nine months of chemotherapy.

Thirty years ago, patients would almost all have an amputation. Today, 90 percent will have limb-sparing surgery. Forty years ago, amputation was the only treatment and survival was dismal.

Metastatic cancers to bone are treated (with surgery) only if there is a fracture or an impending fracture. If there is no risk for fracture, they are most likely to be treated with radiation therapy and /or chemotherapy.

Q: You also specialize in soft tissue tumors? What are these, and how do they differ from, say, tumors involving organs like the brain, lungs or stomach?

A: There are two basic types of cancer: sarcomas and carcinomas. Sarcomas tend to arise from connective tissue such as bone, cartilage, muscle and fibrous tissue. Carcinomas tend to arise from organ tissues, such as bowel, breast, prostate, liver and kidney. Soft tissue tumors can be benign or malignant. Benign soft tissue tumors required simple excision or observation. Soft tissue sarcomas, on the other hand, require aggressive surgical removal and are usually treated with radiation. On occasion, chemotherapy is also used. Diagnosis is frequently delayed because of the lack of pain associated with soft tissue sarcomas.