Clinical data was obtained from 90 patients, aged ≥65 years, with a diagnosis of primary malignant bone or soft tissue tumors (bone, 20 cases; and soft tissue, 70 cases), treated between March 1993 and May 2013 at the Department of Orthopedic Surgery, Osaka City University Hospital Affiliated to Osaka City University Garduate School of Medicine (Osaka, Japan). The data was not fully analyzed until the last follow-up appointment in September 2013. The study population consisted of 46 male and 44 female patients, with a mean age at diagnosis of 75.2±6.8 years (range, 65–94 years). The median follow-up time in the present study was 44.8 months (range, 1–163 months). The present study was approved by the Institutional Review Board of Osaka City University Graduate School of Medicine. Written informed consent was obtained from all patients.

On initial presentation to the Osaka City University Hospital, patients underwent radiological evaluated using plain radiographs, local computed tomography (CT) and magnetic resonance imaging (MRI) with or without gadolinium enhancement. Distant metastases to the lungs were also checked for using CT. Systemic metastases were screened using fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT. Radiologically, if a malignant tumor was suspected it was recommended that the patient underwent a biopsy procedure. All biopsy specimens of resected tissues were diagnosed by a pathologist with specialized training and expertise in sarcoma pathology, using standard diagnostic criteria for bone and soft tissue sarcoma subtyping (14). The histological grade was determined according to the four grade system for bone tumors (15) and according to the Federation Nationale des Centres de Lutte Contres le Cancer grading system for soft tissue tumors (16). The grading system for bone tumors, with the exception of the Ewing sarcoma, was based on the technique described by Broders (15). Grade 1 and 2 tumors were considered as low grade, and grade 3 and 4 tumors as high grade. With regard to soft tissue tumors, Grade 1 tumors were classified as low grade, and grade 2 and 3 tumors were classified as high grade. The clinical staging of each patient was evaluated in accordance with the American Joint Committee on Cancer 7th edition for soft tissue tumors and bone cancer (17,18).

The following parameters were evaluated prior to treatment: Age, gender, tumor depth, tumor site, tumor size, tumor type (bone or soft tissue tumor), histological diagnosis, histological grade, preoperative physical status using the American Society of Anesthesiologists-Physical Status (ASA-PS) classification (19) and oncological outcome. Tumor size and location were estimated using MRI and/or CT, and size was classified as <5 cm, 5–15 cm and >15 cm. The ASA-PS scores were assessed by anesthesiologists regarding the risks associated with surgery. Surgical margins of the resected specimens were evaluated according to the guidelines of the Japanese Orthopedic Association (20).

Following treatment, patients were generally followed up at regular intervals of 3 months, with local examination and chest radiographs or CT for the first 2 years post treatment. Between 3 and 5 years post treatment, patients were followed up every 6 months and yearly thereafter. MRI scans were also conducted in order to supplement local examination for the detection of local recurrence every 6 months for first 3 years following treatment. Patients treated more recently were followed up monthly, with physical examination for the first 3 months post treatment and the last patient to undergo treatment in May 2013 was followed up for 4 months. The follow-up time was defined as the interval from the definitive tumor treatment (surgery or radiotherapy) to the last follow-up.

Curves for the overall survival of patients with sarcoma following treatment were plotted using the Kaplan-Meier method (21). The log-rank test was used to compare overall survival between the subgroups of patients (22). The Cox proportional hazards regression model was used to assess the ability of the patient characteristics to predict overall survival (23). Univariate analysis was performed by means of the log-rank test. Multivariate analysis was performed using the Cox proportional hazards regression model, including only factors where P<0.1 in the univariate analysis. In all analyses, P<0.05 was considered to indicate a statistically significant difference between values. The SAS system (SAS 9.3; SAS Institute, Inc., Cary, NC, USA) was used throughout to perform the various analyses.

Clinical information for the elderly patients is summarized in Table I. The median patient age at the time of the initial visit to the Department of Orthopedic Surgery, Osaka City University Hospital was 75.2 years (range, 65–94 years); the study population consisted of 46 male and 44 female patients. Concerning the evaluation of preoperative physical status, there were 21 patients who had associated comorbidities with an ASA-PS score of ≥3; of note, cardiovascular comorbidities, including hypertension, ischemic heart disease, previous myocardial infarction and previous cerebrovascular accident, accounted for a number of the total documented conditions (19). The locations of bone tumors were as follows: Femur, n=5; pelvis, n=5; rib, n=3; sacrum, n=2; humerus, n=2; tibia, n=1; and scapula, n=1. The locations of soft tissue tumors were the lower limb in 38 patients, trunk in 19 patients and upper limbs in 13 patients.

Histological diagnosis of the patients is summarized in Table II. Of the 20 bone sarcomas, 12 were chondrosarcomas, 4 were osteosarcomas, 3 were chordomas and 1 was a round cell sarcoma. Of the 70 soft tissue sarcomas, 39 were liposarcomas, 11 were leiomyosarcomas, 7 were myxofibrosarcomas, 6 were pleomorphic malignant fibrous histiocytomas, 2 were malignant peripheral nerve sheath tumors and there was 1 case each of fibrosarcoma, synovial sarcoma, malignant solitary fibrous tumor, plasmacytoma and epithelioid sarcoma.

A total of 79 patients underwent surgical resection of their tumors; of which, the surgical margins were evaluated as being wide in 59 cases, marginal in 17 cases and intralesional in 3 cases. A further 11 patients did not receive surgery due to the location of their tumors, which made resection difficult; in these cases, preoperative evaluation indicated that they were in an unsuitable condition for surgery or the patient opted not to undergo surgery. A total of 5 patients received radiation therapy, of which 3 underwent heavy particle beam therapy. A total of 4 patients received chemotherapy and the best supportive care was selected for 2 patient. No patients underwent amputation or disarticulation.

All patients were followed up at the Department of Orthopedic Surgery, Osaka City University Hospital. The average follow-up period was 44.8 months (range, 1–163 months). Regarding oncological outcome at the last follow-up, 52 patients were in a continuous disease-free condition, 8 demonstrated no evidence of disease, 13 were alive with disease, 15 succumbed to the disease and 2 mortalities occurred due to unassociated causes.

Univariate analysis revealed that ASA-PS was a statistically significant prognostic factor for the overall survival rate of patients (P=0.002) (Table III). In addition, using multivariate analysis, ASA-PS was identified as a significant prognostic factor (P=0.003), as was tumor grade (P=0.048) (Table IV).

The 5-year overall survival rate was calculated using the Kaplan-Meier survival curve to be 77.5% (Fig. 1). There was no significant difference in 5-year overall survival between patients aged 65–74-years and patients aged ≥75 years (P=0.23) (Fig. 2). In addition, no significant difference was identified between tumor types (bone vs. soft tissue sarcoma; P=0.43); by contrast, a significant difference was observed for the ASA-PS score (P=0.001) (Fig. 3) and tumor grade (P=0.04) (Fig. 4). The 5-year overall survival rate for patients with an ASA-PS score of ≥3 was decreased compared with that for patients with ASA-PSs score of 1 and 2 (45.5 vs. 79.7%). Furthermore, the 5-year overall survival rate for patients with a high-grade tumor was reduced compared with that for patients with a low grade tumor (70.8 vs. 95.2%).