A total of 4274 patients with advanced STS met the inclusion criteria for this study (Table 1). Patients were on average 77.8 years of age (SD, 7.3; range 65–104 years) at the time of advanced STS diagnosis and 49.2% were male (Table 2). The mean (SD) CCI score was 2.8 (2.33), and 69.2, 18.3, and 6.5% of patients had a history of hypertension, congestive heart failure, and myocardial infarction, respectively.
At initial diagnosis, 36.0% of patients had metastatic (distant) disease; the remaining majority (64.0%) were diagnosed at earlier stages of disease and had claims based indicators of progression to advanced STS (Table 2) with a mean (SD) interval of 16.6 (23.0) months from initial diagnosis. Nodal disease (without any distant metastases) was observed only among 1.6% of patients at initial diagnosis. The most common histologic category was leiomyosarcoma (n = 922; 21.6%), followed by UPS (n = 652; 15.3%), liposarcoma (n = 554; 13.0%), vascular sarcoma (n = 357; 8.4%), fibroblastic/myofibroblastic sarcoma (n = 227; 5.3%), nerve sheath sarcoma (n = 106; 2.5%), rhabdomyosarcoma (n = 98; 2.3%), and synovial sarcoma (n = 49; 1.1%); the remaining 30.6% (n = 1309) had other or NOS histologic categories. A few variations in patient and tumor characteristics by tumor histology were evident: 66.7% of patients with leiomyosarcoma were female; patients with synovial sarcoma had a mean age of 74.1 years, and 54.1, 40.8, 48.7% of patients with rhabdomyosarcoma, synovial sarcoma, and other/NOS histology, respectively, had distant stage of disease at initial STS diagnosis (Table 2). Overall, the most common specified anatomic tumor site was lower limb (21.9%) (Appendix 2: Table 7), and the most common known tumor grade was undifferentiated (30.7%) (Table 2). The average observed follow-up time from advanced STS diagnosis was 1.7 years (SD, 2.36) (Table 2).
Cancer-directed treatment was received by 62.1% of patients. Radiation was received by 40.0% of patients and surgery was received by 10.3% of patients. The mean (SD) age of patients who received cancer-directed treatment was 76.5 (6.9) years and the mean (SD) CCI score was 2.5 (2.1), with hypertension, diabetes (without complications), chronic pulmonary disease, peripheral vascular disease, and congestive heart failure observed among 68.9, 28.4, 24.4, 18.1, and 14.6% of patients, respectively (Additional file 1: Table S1). Chemotherapy, biologic therapy, and targeted therapy were received by 27.5, 1.9, and 1.3% of patients, respectively. Among the 28.7% of all patients with advanced STS who received chemotherapy, biologic therapy, or targeted therapy (n = 1227), the mean duration of first-line therapy was 4.1 months (SD, 4.1) (Table 3). Second-line therapy was received by 11.1% (n = 476) of all patients; the mean duration of second-line treatment was 4.6 months (SD, 5.3). Among the 4.4% of all patients with advanced STS who received at least third-line therapy (n = 189), the mean duration of third-line therapy was 4 months (SD, 3.4). The proportion of patients receiving up to three lines of treatment and duration of each line of treatment by histologic category is shown in Table 3. First-line chemotherapy was most commonly received by patients with synovial sarcoma (42.9%), leiomyosarcoma (37.0%), and vascular sarcoma (36.4%).
Overall, the most common regimen during first-line therapy was docetaxel plus gemcitabine (26.5%), followed by doxorubicin monotherapy (18.8%), gemcitabine monotherapy (9.1%), paclitaxel monotherapy (5.5%), and bevacizumab monotherapy (3.3%). Docetaxel plus gemcitabine was the most common first-line therapy for patients with all histologic categories except liposarcoma (for whom it was doxorubicin monotherapy [24.3%]) and vascular sarcoma (for whom it was paclitaxel monotherapy [40.0%]) (Table 4). During first-line therapy, doxorubicin plus ifosfamide was received by 3.0% and ifosfamide monotherapy was received by 2.7% of patients. Among all patients who received doxorubicin alone or a doxorubicin-based first-line therapy (n = 371), 29.7% received liposomal doxorubicin, and 5.9% received the cardioprotective agent dexrazoxane.
Among patients who received second-line (n = 476) and third-line (n = 189) therapy, doxorubicin monotherapy (second line, 21.2%; third line, 14.8%), docetaxel plus gemcitabine (second line, 17.4%; third line, 11.1%), and gemcitabine monotherapy (second line, 8.6%; third line, 11.1%) were most common (Table 4). Among the 476 patients who received second-line therapy, the most common treatment sequence was first-line docetaxel plus gemcitabine followed by second-line doxorubicin monotherapy (n = 56, 11.8%). Among the 189 patients who received third-line therapy, the most common sequence was first-line doxorubicin followed by second-line gemcitabine and then third-line docetaxel plus gemcitabine (n ≤ 11). Among patients who received second- or third-line therapy, ≤ 11 received dexrazoxane.
Among patients who received supportive care only (n = 1618, 37.86%), the mean (SD) age was 80.0 (7.5) years (Additional file 1: Table S1). Hypertension (69.6%), diabetes without complications (28.7%), chronic pulmonary disease (28.1%), congestive heart failure (24.5%), and peripheral vascular disease (22.6%) were the most common baseline comorbidities and the mean (SD) CCI score was 3.1 (2.6).
The majority of patients (n = 3565; 83.4%) died during study follow-up, with a median survival (95% CI) of 8.9 months (8.3, 9.7) from the time of advanced STS diagnosis. Median survival (95% CI) from advanced STS diagnosis among patients who received cancer-directed therapy was 13.6 months (12.9, 14.6), and among those who received supportive care it was 2.8 months (2.6, 3.4) (Table 5 and Fig. 1). Survival estimates for each histologic category is shown in Table 5. Estimated survival from advanced STS diagnosis varied by histologic category with median survival ranging from 21.4 months (15.6, 26.8) for patients with fibroblastic/myofibroblastic sarcoma to 3.0 months (1.8, 5.7) for patients with rhabdomyosarcoma.