Extraosseous osteosarcoma: response to treatment and long-term outcome.
OBJECTIVE
To evaluate the clinicopathologic features of extraosseous osteosarcoma (EOO), a rare soft tissue form of osteosarcoma, and to examine its response to multimodality therapy.


METHODS
The medical records of all patients with EOO evaluated at The University of Texas M.D. Anderson Cancer Center between 1960 and 1999 were reviewed for clinicopathologic factors, treatment, and outcome.


RESULTS
Sixty consecutive patients with EOO were identified, including 38 patients with localized (American Joint Committee on Cancer stages I to III) disease. The majority of patients presented with T2 tumors (n = 35, 58%), and 90% of tumors were located beneath the investing fascia. Twenty-seven patients with measurable and assessable disease were treated with doxorubicin-based chemotherapy (median doxorubicin starting dose, 75 mg/m(2); median number of cycles, four). The overall response rate was 19%, with two complete and three partial responses; one (6%) of 18 doxorubicin-treated patients who underwent subsequent surgery had a pathologic complete response. For the subset of 30 patients with localized disease treated at M.D. Anderson, the 5-year actuarial local recurrence-free, distant recurrence-free, event-free, and disease-specific survival rates were 82% (95% confidence interval [CI], 70% to 98%), 64% (95% CI, 43% to 93%), 47% (95% CI, 30% to 70%), and 46% (95% CI, 26% to 80%), respectively.


CONCLUSIONS
EOO should be considered clinically and therapeutically distinct from osseous osteosarcoma. Radiographic response rates and pathologic complete response rates to doxorubicin-based systemic therapy are low.
Ahmad
Syed A
SA
Multidisciplinary Sarcoma Center and Department of Biostatistics, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030-4009, USA.
Patel
Shreyaskumar R
SR
Ballo
Matthew T
MT
Baker
Treneth P
TP
Yasko
Alan W
AW
Wang
Xuemei
X
Feig
Barry W
BW
Hunt
Kelly K
KK
Lin
Patrick P
PP
Weber
Kristen L
KL
Chen
Lei L
LL
Zagars
Gunar K
GK
Pollock
Raphael E
RE
Benjamin
Robert S
RS
Pisters
Peter W T
PW
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*; D011379:Prognosis; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome
D004317:Doxorubicin