SLR - November 2018 - Robby J. Caballes(1)

High-Grade Osteosarcoma of the Foot: Presentation, Treatment, Prognostic Factors and Outcome of 23 Cooperative Osteosarcoma Study Group COSS Patients

Reference: Schuster A, Kager L, Reichardt P, Baumhoer D, Csóka M, Hecker-Nolting S, Lang S, Lorenzen S, Mayer-Steinacker R, Von Kalle T, Kevric M, Werner M, Windhager R, Wirth T, Bielack S. High-Grade Osteosarcoma of the Foot: Presentation, Treatment, Prognostic Factors and Outcome of 23 Cooperative Osteosarcoma Study Group COSS Patients. Sarcoma. 2018 May.

Scientific Literature Review

Reviewed By: Robby J. Caballes, DPM
Residency Program: Bethesda Hospital, Boynton Beach, FL

Podiatric Relevance: Osteosarcoma of the foot is exceedingly rare. Only 1 percent of all osteosarcomas are reported in the literature. Consequently, available information on characteristics and optimal management is limited. This retrospective analysis investigates primary high-grade osteosarcoma of the foot in one of the largest cohort studies reported to date. This study examines the presentation, treatment and prognosis of patients with this rare tumor entity. Overwhelming evidence suggests poor prognosis associated with osteosarcoma in the other extremities. This study supports the same findings in the foot and provides a justified argument for aggressive surgical intervention (e.g., amputation/resection) secondary to poor prognosis.

Methods: This retrospective analysis investigated 23 patients (median age 32; 10 female; 13 male) with primary, previously untreated high-grade osteosarcoma of the foot between January 1980 and April 2016. All patients underwent operation primarily or following chemotherapy. Median follow-up period was 4.2 years with a minimum of three months. Diagnostic procedures included X-ray, CT, MRI and bone scan to assess extension of the primary tumor. Additional lab biomarkers were examined. Level of surgical resection was determined by the local surgeon with the goal of wide/radical resection. All patients were treated on an intent-to-treat basis. The Kaplan-Meier method was utilized for survival analysis with additional tests (Mantel-Cox and Breslow’s test) utilized for comparison. Overall survival was calculated from time of diagnostic biopsy until death. A p-value <0.05 was considered statistically significant.

Results: In 21/23 patients, eight (38 percent) complained solely of pain, two (10 percent) registered swelling, while 11 (52 percent) reported both. Pain was the most frequent presenting symptom. The tarsal bones were the most frequently affected sites. Median duration between first symptoms and diagnostic biopsy was 154 days. Localization of the primary tumor was found as follows: phalanx (two patients, 9 percent); metatarsal bone (five patients, 21 percent); tarsal bone (16 patients, 70 percent). Three patients had evidence of primary metastases to the lungs/inguinal lymph nodes. Serum alkaline phosphatase and lactate dehydrogenase levels were normal in the majority of patients. Nineteen patients (83 percent) underwent amputation, and four (17 percent) underwent foot-saving resections. At last follow-up, 15 patients were alive; eight had died. The five-year overall and event-free survival estimates were 64 percent (standard error: 12 percent) and 54 percent (standard error: 13 percent). Findings showed that high-grade osteosarcoma in the foot had similar outcomes to other sites.

Conclusion: Prognosis of patients with osteosarcoma is generally poor. Although studies are limited in the foot, similar results/findings in this cohort study argue in favor of treating these osteosarcomas similar to that in other extremities. The authors provide justification for achieving complete surgical remission secondary to the poor prognosis and response to chemotherapy. The authors believe an aggressive surgical approach is well-justified, and complete surgical remission—by way of amputation/resection—appears to be the strongest positive predictor for event-free and overall survival.

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