Primary foot sarcomas of bone and soft tissue tumors are rare. Malignant tumors of the foot account for approximately 2% of tumors that occur in the entire body (1). Papagelopoulos et al proposed that fewer than 5% of all malignancies of bone and soft tissues originate in the foot (2). The pathology series of the Mayo Clinic on 5124 bone sarcomas found that approximately 1.2% of malignant bone tumors in the body occur in the foot (3). Approximately 2.2% of cases of 4496 soft tissue sarcomas (STS) originated in the foot in patients diagnosed at the Memorial Sloan-Kettering Cancer Center (MSKCC) between 1982 and 2000 (4). Due to the rarity of this disease, few reports have described the prognostic factors correlating with the clinical outcome in patients with bone and STS of the foot.

Recently, owing to multidisciplinary advances in excision, reconstruction and adjuvant therapy, limb salvage procedure has become the technique of choice for lower extremity sarcoma, particularly with adjuvant radiotherapy. The usefulness of radiotherapy for local control of sarcomas has been well demonstrated in patients with foot sarcomas (5). Since radiotherapy has been indicated for sarcoma patients with positive microscopic margins in our institutions, only a small number of such patients have received radiotherapy. This makes it possible to analyze the significance of radiotherapy for local control in patients with foot sarcomas. Another crucial issue for limb salvage surgery is advances in plastic reconstructive procedures (5), although few studies have demonstrated the importance of flaps.

Even successful limb salvage surgery may occasionally not be associated with a functional limb. Postoperative function in patients with foot sarcoma has not been reported in detail. Due to the lack of fascial boundaries and the proximity to neurovascular and complex structures, the tumor should be resected with safe and wider margins (6), leading to difficulty in preserving the function of the affected limb. In cases with limb salvage surgery and amputation, postoperative function should be evaluated to determine the indication of operative procedures.

The aims of this study were to clarify i) prognostic factors in patients with sarcomas arising in the foot, ii) rate of local control (mostly without radiotherapy), iii) feasibility of limb salvage surgery and iv) postoperative function.

Fewer than 10% of soft tissue sarcomas arise in the foot and ankle (14,15). Studies have described the management of soft tissue sarcomas arising at this site (5,16,17). However, few studies have analyzed the prognostic factors involved due to the small number of such cases. Sarcomas of the distal extremity are associated with improved survival rates as compared to sarcomas located elsewhere in the body. For example, Zeytoonjian et al showed an overall death rate from all sarcomas of 26.6% in contrast to 10.3% for those in the foot and ankle (15). This improved prognosis is attributable to the fact that even small lesions in the foot and ankle are likely to be observed early. Although patients with foot sarcomas have a more favorable prognosis, prognostic factors should be clarified to determine the most appropriate treatment modality for such patients.

The current study showed that size (>5 cm) (LRFS and MFS), amputation as a operative procedure (OAS and MFS) and bone reconstruction (LRFS and MFS) had a significant adverse impact on prognosis. Thacker et al reported that no factors including tumor grade, size (5 cm), site, planned vs. unplanned excisions, radiotherapy and amputation vs. limb salvage, had a significant impact on the local control of tumors (18). Talbert et al reported that the size of the primary tumor correlated with total tumor-free survival, whereas no factors correlated with local control (19). Considering the characteristics of foot anatomy, including the lack of abundant muscle and subcutaneous structures, large tumors easily invade adjacent tissue, with more cases thus requiring amputation or bone reconstruction following resection. Taken together, correlation of factors derived from the current study, such as larger size, amputation and bone reconstruction, may occur. Another possible explanation for the poor prognosis of patients with amputation is attributed to the histological type. The treatment modality of operative treatment in our institutions has shown a trend towards amputation for patients with epithelioid and clear cell sarcomas. Of the 5 patients who succumbed to the disease, 3 had either epithelioid or clear cell sarcomas and all 3 patients received amputation. Analysis with larger cohorts of patients may lead to the omission of amputation from the poor prognostic factors with multivariate analysis, including histological type.

Few reports have described bone sarcoma of the foot. Chou et al reported 17 bone sarcomas with an equal proportion of osteosarcoma and chondrosarcoma (1). Another study reported that chondrosarcoma occurs three times more often than osteosarcoma (20). However, these studies did not describe the oncological outcome or postoperative function. Prognostic factors for patients with bone sarcomas were not derived in the current study either, probably due to the small number of cases and/or heterogeneity of histological types (Table I).

Given that benign lesions outnumber malignant ones by a ratio of 100:1 (7), unplanned excision is a relatively common occurrence in soft tissue sarcomas of the foot and ankle. Temple et al (14) and Cribb et al (5) observed that 51 and 56% of the foot and ankle tumors they studied had unplanned excisions at other institutions, respectively. These patients required more complicated surgery, had more perioperative complications and were more likely to be treated with adjuvant radiotherapy; however, there were no differences between the oncological outcomes (14). The current study had 10 (42%) cases of unplanned excision with soft tissue sarcoma, which are comparable to the rates noted in previous studies. Of note, patients with unplanned excisions had a significantly improved prognosis (OAS and MFS) as compared with patients with planned excisions. As previously reported (12), unplanned excisions tended to be performed in patients with superficial and small tumors. In this study, tumors undergoing unplanned excisions were smaller (3.3 cm) than those (4.0 cm) subjected to planned excisions.

Although 2 of the 24 patients with soft tissue sarcomas received radiotherapy in this series, only 2 (8%) had local recurrence. Talbert et al reported a 19% local recurrence rate in 39 cases with soft tissue sarcomas of the foot and ankle (19). Thacker et al reported that the local recurrence rate was 13.5% in their series of 52 cases (18). In these studies, 100 and 35% of the patients received radiotherapy, respectively, in contrast to only 8% in the current study. Given that amputation was performed in 6 (25%) of the 24 patients in the current study, comparable with the 24% (18) and 18% (19) of previous reports, limb salvage surgery with a microscopically negative margin (94%; 17 of 18 cases) is capable of preventing local recurrence without adjuvant radiotherapy. Moreover, considering that major wound complications (i.e., delayed wound healing or need for operative intervention) reportedly occur in approximately 17% of patients following operative resection with postoperative radiotherapy (21), these complications may be mitigated if radiotherapy is omitted.

The next issue considered in this study involved whether limb salvage surgery is feasible for patients with foot sarcomas, as well as the benefits thereof. Given the excellent functional results that are obtained with below-the-knee amputation, the benefits of time-consuming operative reconstruction are often questionable. Comparisons of the quality of life between limb salvage and amputation for sarcomas of the lower extremity show little difference (22,23), but these studies were not specific for the distal part. A recent study revealed that limb salvage is capable of achieving good functional results, assessed with Toronto Extremity Salvage Score (TESS) score (5), which is consistent with our results that ISOLS scores in the limb salvage group were significantly better than those of the amputation group. In cases in which a safe margin can be achieved, limb salvage surgery is indicated in patients with sarcomas of the foot and ankle. To achieve limb salvage surgery, reconstruction by plastic surgery is required. Recent advances in plastic operative reconstruction have rendered such limb salvage surgery possible. In this study, 17 out of 18 patients with soft tissue sarcomas required free or local flaps. In terms of local control, the low recurrence rate (8%) was attributed to a negative operative margin, resulting in larger defects following excision. These extensive defects were successfully reconstructed by plastic and reconstructive surgery.

The present study showed that the function of the patients with limb salvage surgery was better than that of those with amputation, which was not consistent with a previous report in which the MSTS functional scores did not differ between limb salvage and amputation (18). The current study included 7 cases (29%) with clear cell or epithelioid sarcoma. Epithelioid sarcoma has a high risk of regional lymph node metastasis, and ‘local metastasis’ at some distance from the primary tumor (24). Considering the high ‘regional metastasis’ of these diseases, it is occasionally preferable to amputate at higher levels. Two cases with an epithelioid sarcoma and a clear cell sarcoma underwent below-the-knee amputation and hip disarticulation for the foot primary tumor, respectively, in this study. Cases with amputation at higher levels caused the low ISOLS scores in the amputation group. Patients with larger tumors had significantly lower scores. Moreover, reconstruction procedures with free flap tended to have lower functional scores, suggesting that larger defects after excision correlate with poorer functional outcome.

One of the limitations of this study was the small number of cases, particularly those with bone sarcomas. Due to the heterogeneous nature of these lesions, treatment modalities also markedly differed. Particular patterns of invasion and metastasis by the tumors, particularly clear cell and epithelial sarcomas, affected the range of excision. Another limitation was the indication of chemotherapy for patients with foot sarcomas. However, given that the modality of chemotherapy has not been well-defined for patients with soft tissue sarcomas, and that soft tissue sarcomas in foot include both relatively responsive (synovial sarcoma) and non-responsive (clear cell and epithelioid sarcomas) tumors, the significance of chemotherapy should be analyzed independently according to histological type.

In conclusion, although the anatomical features of the foot include insufficient barriers against sarcomatous spread, primary resections or additional resections after unplanned excisions with microscopically negative margins are able to achieve local control without radiotherapy. Plastic reconstructive procedures permit limb salvage and well-preserved limb function. However, patients with larger tumors, requiring amputation or bone reconstruction require novel treatment strategies to improve their oncological and functional outcomes.