DISCUSSION
Bone sarcomas of small bones of the hands or feet are rare malignancies, and have the potential for both local aggressive performance and distant metastasis. Ogose et al5 found that chondrosarcoma of the small bones of the hands or feet had the potential for metastasis and high mortality. Therefore, equal attention should be paid to the prognosis of patients with bone sarcomas of both long and short bones. Previous studies mostly reported on soft-tissue sarcomas of the hands or feet rather than osseous malignancies.6–8 Recently, Yang et al9 documented the clinical features and incidence of malignant osseous foot tumors and evaluated the clinical course and outcomes of the malignancy. Henderson et al10 retrospectively analyzed the clinical presentation, radiographic features, and treatment choice of malignant osseous hand tumors. However, these studies had small heterogeneous cohorts, and the prognostic results of those patients were not analyzed. To our knowledge, the current study is the first to report the factors that affect the prognostic factors that affect the survival of patients with primary malignant bone tumors of the hands or feet, which is often ignored by orthopedists. Furthermore, the study used multivariate regression analysis to identify possible prognostic factors for survival in those patients.
Although many case reports and case series reported bone sarcomas of the hands or feet, there was a lack of demographic knowledge information. Farzan et al11 reported 99 osseous tumors of the hands and only found two chondrosarcomas, one osteosarcoma, and one Ewing sarcoma involving the hand skeleton, suggesting that bone sarcomas of the small bones were rare. In the current study, we identified 457 cases of primary malignant bone tumors of the hands or feet based on the SEER database from 1973 to 2013. Chondrosarcoma was the most common primary malignant bone tumor in the hands, feet, or both, followed by Ewing sarcoma and osteosarcoma; 69.9% of cases were chondrosarcoma. Murari et al2 found that the most common malignant neoplasm in the bones of the feet was chondrosarcoma, which accounted for 52.3% of malignant neoplasms and is similar to the current findings (44.6%). Moreover, Saglık et al12 reported that the most common nonmetastatic malignant lesions of the bones in the hands were also chondrosarcomas (n=6/16; 37.5%). However, Ewing sarcoma was the most common malignancy of the bones of the feet (17/68; 25%) in a study by Bakotic and Huvos.13 Interestingly, the current study revealed that 48 (10.5%) patients had metastatic disease at initial presentation and most of them (n=43) were due to bone sarcomas in feet. No gender predilection was found both in either the hand or foot cohort. As the year at diagnosis increased, the number of patients in the series also increased. Moreover, the age range of patients in the cohort was very wide (from 1 to 102 years old). Therefore, it is important to suspect short bone sarcomas in patients of any age to reduce the risk of a delayed diagnosis. On average, patients presenting with bone sarcomas of the hands were older than those of the feet.
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Most studies on bone sarcoma and survival primarily consisted of patients with appendicular or pelvic or spine disease. In general, the outcome among patients with sarcomas involving the pelvic bones or spine is much poorer than those with appendicular disease.14–17 Jawad et al18 found that the 5-year OS of all patients with pelvic sarcomas was 47%. Similarly, Mukherjee et al14 reported that for all patients with sarcomas in the spine, the estimated 5- and 10-year OS rates were 41% and 34%, respectively. However, the outcome and prognosis of patients with sarcomas of the hands or feet have not been reported frequently because of its rarity. Bishop et al8 evaluated 85 patients with soft-tissue sarcomas of the hands or feet and found that the 5- and 10-year OS rates were 89% and 77%, respectively. In the current study, the OS for osseous sarcomas of the hands or feet was 75.7% and 66.1% at 5 and 10 years, respectively, suggesting that the prognosis of these patients may be poorer than the OS of those with soft-tissue sarcomas. More studies are needed to confirm it. In general, the prognosis of patients with bone sarcoma of the small bones appears to be more favorable than that of patients with disease affecting the long bones, who have an estimated 5-year survival ranging from 45% to 75%.19 Additionally, the current study showed that the 5- and 10-year OS rates for patients with malignant osseous foot tumors were 72.2% and 63.7% and the 5- and 10-year CSS rates were 74.1% and 68.0%, respectively. These outcomes were poorer than those of patients with malignant osseous hand tumors, whose OS rates were 81.2% and 70.9% and CSS rates were 86.3% and 83.4%, respectively, at the same time points.
In terms of prognostic determinants, both univariate and multivariate analyses showed that age >40 years was associated with worse OS but not worse CSS. Mirabello et al20 also revealed that the survival rates for osteosarcomas were highest in the youngest age group, and lowest in elderly patients. For both OS and CSS, race was not associated with significant differences in survival. The current study noted that female gender was associated with a reduction in OS. However, gender was not an independent prognostic indicator of either OS or CSS. In addition, a more recent year of diagnosis was associated with better CSS but not OS, suggesting that the treatment of bone sarcomas in the hands or feet has improved significantly. Adjuvant therapy such as chemotherapy and radiation and the progress of multimodality imaging such as magnetic resonance imaging may be the contributed factors.8 The current multivariate survival analysis revealed that tumor location was not an independent prognostic indicator of either OS or CSS, suggesting that bone sarcomas in the hands or feet could be reported together for further analyses. Ewing sarcoma was adversely associated with CSS, but the significance was lost on multivariate analysis. Although tumor type was not an independent prognostic indicator for OS or CSS, a trend of decreased OS and CSS was observed for patients with Ewing sarcoma or osteosarcoma compared with those with chondrosarcoma. In addition, tumor sequence was an independent prognostic indicator of OS but not CSS, suggesting that patients with second or more primary bone sarcomas in their hands or feet may have a worse prognosis than those with a first primary tumor.
Stage, grade, and surgery have been previously recognized as predictors of survival in patients with malignant tumors.21–23 Similarly, these three factors were independent predictors of OS and CSS in the current study. Patients with metastatic disease at initial presentation have a poorer prognosis than those with localized disease. Furthermore, metastasis at diagnosis was the greatest indicator of both OS (HR=3.839; 95% CI, 2.375–6.205) and CSS (HR=7.040; 95% CI, 3.708–13.364). Survival analysis using Kaplan–Meier curves (Figures 1B and 2B) revealed that the 5-year OS and CSS rates were 30.9% and 28.7%, respectively. Bone sarcomas are highly metastatic tumors.15,24,25 Many studies suggested that pulmonary metastasectomy for sarcomas may confer better survival.26–28Therefore, surgical removal of the primary tumor together with all clinically evident metastatic disease should be addressed and may be beneficial for prolonging survival in patients with bone sarcomas of the hands or feet and metastasis at diagnosis. Surgery treatment for patients with bone sarcomas of the hands or feet usually included amputation, wide resection, and combined modality therapy such as radiotherapy and chemotherapy.29 Yang et al9 reported that most of the patients with primary malignant bone tumors of the feet received surgical amputation, regardless of tumor histology or site and achieved excellent outcomes. Additionally, they thought that amputation was an appropriate management option for patients who had undergone previous accidental excisions. Careful staging, precise grading, and appropriate treatment are critical for improving prognosis as the short bones are an uncommon site for chondrosarcoma, Ewing sarcoma, and osteosarcoma.
Limitations
The SEER program database does not gather information about local recurrence or metastasis during the follow-up, which may affect prognosis. Additionally, other known prognostic factors for cancer survival, such as surgical method and chemotherapy, are not available in this database, which may be the contributing factors. Further research is needed to confirm their prognostic value. Nevertheless, the SEER program database provides important insights into rare cancers such as bone sarcomas of the hands or feet.
