Demographic and clinical characteristics of patients with DDC and COS
Among the 228 patients with DDC, there were 123 males (53.9%) and 105 females (46.1%). The overall median age of the patients was 63 years. In the end, 153 patients (67.1%) with DDC died, the median OS of the patients was 14 ±1.3 months, and the 3- and 5-year OS rates of the patients were 33.3% and 26.5%, respectively. Of the 631 patients with COS, there were 373 males (59.1%) and 258 females (40.9%), with a median age of 18 years. A total of 247 patients (39.1%) with COS died, the median OS of the patients was 233 ±38.1 months, and the 3- and 5-year OS rates of the patients were 71.5% and 63.8%, respectively. The 3- and 5-year OS rates for DDC were significantly lower than those for COS (p< 0.001) (Table 1, Figure 2).
Regarding demographic characteristics, most of the patients with DDC were in the age range of 40 to 70 years (64.9%), and most of the patients with COS were in the age range of 39 years (81.0%). The proportions of white and black patients with DDC were 91.7% and 2.6%, respectively, and the percentages of white and black patients with COS were 74.5% and 15.5%, respectively. There were significant differences in age and ethnic distribution between the two diseases (p< 0.001, p< 0.001), but there was no significant difference in the sex distribution between the two diseases.
In terms of the clinical characteristics of the tumors, the distributions of T stage, N stage and lung metastasis were similar between the two diseases. Most of the two kinds of tumors were located in the bone and joints, and the proportion of tumors originating from soft tissue in DDC was higher than that in COS (6.6% vs 2.5%, p= 0.019). Among the two diseases, the specific growth site of the tumors was most often the lower limbs, followed by the skull and mandibles, pelvic bones, and vertebral or chest bone. The occurrence of DDC in the upper and lower limbs was higher than that of COS (8.8% vs 7.6%, 68.0% vs 60.1%, p=0.019). In the DDC group, a high pathological grade was predominant. In the COS group, the proportion of grade IV cases was significantly higher than that of grade IV cases (51.3% vs 38.4%, p=0.031). The proportion of tumors with diameters ≥ 8 cm in the DDC group was higher than that in the COS group (47.4% vs 29.6%, p= 0.008). More DDCs were diagnosed with distant metastasis (M1), and the difference in M1 staging between the DDC and COS groups was statistically significant (13.6% vs 6.8%, p=0.015); moreover, the corresponding proportion of AJCC IV staged tumors was higher in the DDC group than in the COS group (14.9% vs 7.0%, p= 0.036). The rates of local excision, radical excision, amputation, and partial resection in the COS group were higher than those in the DDC group (p=0.002). The chemotherapy rate in the COS group was significantly higher than that in the DDC group (85.1% vs 39.5%, p< 0.001) (Table 1).
Univariate analysis of OS-related factors in DDC and COS
The univariate analysis of patient survival is shown in Table 2 and Figure 3. In DDC, age was a factor that affected patient survival; the younger the age was, the better the prognosis would be (p< 0.001). The prognosis of patients with DDC was significantly correlated with M stage. The prognosis of patients with stage M1 was worse than that of patients with stage M0 (p< 0.001). The prognosis of patients with stage I or II disease was better than that of patients with stage III or IV disease (p< 0.001). Lung metastasis was also associated with prognosis. Patients with DDC with lung metastasis had a poorer prognosis than those without lung metastasis (p=0.009). Sex, race, tumor location, pathological grade, tumor size, T stage, N stage, mode of operation and chemotherapy had no effect on the prognosis of patients with DDC (Table 2, Figure 3).
Age can affect the prognosis of patients with COS; the younger the age was, the longer the total survival time would be (p< 0.001). Statistical analysis showed that the prognosis of female patients with COS was better than that of male patients (p=0.006). The patients with specific tumor growth sites survived, and the survival time of the patients with tumors located in the skull and lower extremities was significantly better than that of patients with tumors located in the pelvis, spine or sternum (p< 0.001). Regarding AJCC staging, the higher the T stage of COS was, the poorer the prognosis of the patients with M1-stage tumors would be (p< 0.001, p< 0.001, p< 0.001), and the survival rate of patients with lung metastasis would also be shorter (p=0.005). Patients with COS who received chemotherapy during the whole treatment had a longer OS time (p< 0.001). (Table 2, Figure 4)
Multivariate analysis of OS-related factors in DDC and COS
The multivariate analysis of patient survival is shown in Tables 3 and 4. For DDC, tumor stage was an independent factor affecting patient prognosis; the higher the tumor stage was, the worse the prognosis would be. Furthermore, chemotherapy was not an independent factor affecting the patient prognosis. Regarding COS, age, sex, tumor stage and chemotherapy were independent factors affecting patient prognosis. Older age, male sex, high tumor stage and not receiving chemotherapy were negatively correlated with prognosis.