Copyright © 2007 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Dempsey S. Springfield, MD*,
Massachusetts General Hospital, Boston, Massachusetts
Posted May 2007
The Rizzoli Orthopaedic Institute in Bologna, Italy, has one of the
world's most extensive collections of musculoskeletal tumor cases. It is my
understanding that when Professor Vittorio Putti assumed the directorship of
the Institute in 1912, he insisted that all records, all radiographs, and all
histologic slides of tumor cases be kept. In 1963, Professor Mario Campanacci
became the Director of the Tumor Center
and further organized the orthopaedic oncology service at the Institute. The
efforts of these two individuals have resulted in exemplary quality of
treatment, dedication to follow-up, and improvement in care. This article is
evidence that the efforts of these pioneers in orthopaedic oncology are paying
dividends.
Almost all secondary chondrosarcomas arising in osteochondromas
are low-grade malignant tumors that carry a low risk of metastasis1.
These tumors are not uncommon, and most centers with active orthopaedic
oncology units will have sufficient experience to be able to provide data on
the natural history of this disease and make suggestions regarding treatment. In
contrast, dedifferentiated chondrosarcoma arising in an osteochondroma is a
distinctly uncommon event, and few centers will have encountered a sufficient
number of them to be able to comment on their natural history or treatment. The
database at the Rizzoli Institute contained twenty cases (nineteen of which included
follow-up) since 1970, which is probably more than the number of cases seen in
any other single institution and enough for us to learn about this specific,
rare condition. By reviewing only the patients seen since 1970, the authors
have excluded tumors treated before what can be considered "the modern era" of
treatment for musculoskeletal tumors.
The single most important finding was the survival of patients treated with adjuvant chemotherapy. This finding, which must be considered conjecture because the groups were not controlled, was both strongly suggestive and dramatic: none of the five patients without metastasis at presentation who were managed without chemotherapy survived, while five of six similar patients who were managed with chemotherapy survived). On the basis of these data, patients with a secondary dedifferentiated chondrosarcoma should be offered chemotherapy. However, as stated in the article, patients with dedifferentiated chondrosarcoma secondary to medullary cartilage lesions have not benefited from adjuvant chemotherapy2.
The second, somewhat surprising finding in this study was
that the prevalence of dedifferentiated chondrosarcoma was essentially equal in
patients with a solitary osteochondroma and patients with multiple hereditary
osteochondroma. At first glance, this finding seems to suggest that the risk of
developing a secondary dedifferentiated chondrosarcoma is the same whether an
individual has a solitary osteochondroma or multiple hereditary osteochondroma,
but that is not true. There are many more patients with a solitary
osteochondroma than there are patients with multiple hereditary osteochondroma.
Therefore, the risk of having a secondary dedifferentiated chondrosarcoma is
less for an individual patient with a solitary osteochondroma than it is for a
patient with multiple hereditary osteochondroma. Calculating the risk is
impossible because the total number of patients with solitary osteochondroma is
not known. Many individuals with a solitary osteochondroma are probably never
diagnosed.
Dedifferentiated chondrosarcoma arising from an
osteochondroma is sufficiently rare that individual cases and small series probably
should be reported so that we can continue to learn more about this rare
condition.
*The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.
References
1. Ahmed AR, Tan TS, Unni KK, Collins MS, Wenger DE, Sim FH. Secondary chondrosarcoma in osteochondroma: report of 107 patients. Clin Orthop Relat Res. 2003;411:193-206.
2. Dickey ID, Rose PS, Fuchs B, Wold LE, Okuno SH, Sim FH, Scully SP. Dedifferentiated chondrosarcoma: role of chemotherapy with updated outcomes. J Bone Joint Surg Am. 2004;86:2412-8.
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