Adjuvant radiotherapy in retroperitoneal sarcomas. A Scandinavian Sarcoma Group study of 97 patients

Figures & data

Table I. Patient and tumour characteristics according to centre in 97 patients with RPS.

	Total (n = 97)	HUH (n = 52)	SUH (n = 45)	p-value
Male gender	50 (51.5)	29 (55.8)	21 (46.7)	0.371
Age, years	62 (15–83)	62 (15–83)	62 (20–83)	0.888
Tumour size, cm	20 (4–60)	18 (4–43)	20 (15–60)	0.534
High malignancy grade	71 (73.2)	44 (84.6)	27 (60.0)	0.006
Histopatological subtype				0.639
Liposarcoma	60 (61.9)	30 (57.7)	30 (66.7)
Leiomyosarcoma	28 (28.9)	17 (32.7)	11 (24.4)
Other	9 (9.3)	5 (9.6)	4 (8.9)
First operation at centre	80 (82.5)	41 (83.7)	39 (86.7)	0.684
Surgical margin				0.474
Negative	54 (55.7)	28 (53.8)	26 (57.8)
Positive	37 (38.1)	22 (42.3)	15 (33.3)
Unknown	6 (6.2)	2 (3.8)	4 (8.9)
Radiotherapy	42 (43.3)	26 (50.0)	16 (35.6)	0.152
Chemotherapy	15 (15.5)	9 (18.0)	6 (13.6)	0.564

Continuous variables are presented as median (range), categorical variables as counts (%). Differences between groups are calculated using Mann-Whitney U-test for continuous variables and Pearson's χ²-test for categorical variables. Some variables have missing data, i.e. n < 97.

HUH, Haukeland University Hospital; RPS, Retroperitoneal Sarcoma; SUH, Skåne University Hospital.

Table II. Patient and tumour characteristics according to RT in 97 patients with RPS.

	Total (n = 97)	RT yes (n = 42)	RT no (n = 55)	p-value
Male gender	50 (51.5)	27 (64.3)	23 (41.8)	0.028
Age, years	62 (15–83)	61 (35–82)	63 (15–83)	0.592
Tumour size, cm	20 (4–60)	19 (6–60)	19 (4–43)	0.508
High malignancy grade	71 (73.2)	34 (81.0)	37 (67.3)	0.132
Histology				0.662
Liposarcoma	60 (61.9)	28 (66.7)	32 (58.2)
Leiomyosarcoma	28 (28.9)	11(26.2)	17 (30.9)
Other	9 (9.3)	3 (7.1)	6 (10.9)
First operation at centre	80 (82.5)	34 (85.0)	46 (85.2)	0.980
Surgical margin				0.974
Negative	54 (55.7)	25 (59.5)	29 (52.7)
Positive	37 (38.1)	17 (40.5)	20 (36.4)
Unknown	6 (6.2)	0	6 (10.9)
Chemotherapy	15 (15.5)	8 (19.5)	7 (13.2)	0.408

Continuous variables are presented as median (range), categorical variables as counts (%). Differences between groups are calculated using Mann-Whitney U-test for continuous variables and Pearson's χ²-test for categorical variables. Some variables have missing data, i.e. n < 97.

RPS, retroperitoneal sarcoma; RT, radiotherapy.

Figure 1. (A) Local recurrence-free survival, (B) metastasis-free survival and (C) overall survival by radiotherapy in 97 patients with retroperitoneal sarcoma. With (solid line) and without radiotherapy (dotted line). Kaplan-Meier plot, p-value is from log rank test.

Figure 2. Local recurrence-free survival by radiotherapy and (A) negative and (B) positive surgical margin in 97 patients with retroperitoneal sarcoma. With (solid line) and without radiotherapy (dotted line). Kaplan-Meier plot, p-value is from log rank test.

Table III. Potential prognostic factors for local recurrence by simple and multiple Cox regression analysis of 97 RPS patients.

	Univariate		Multivariate		Limited model
Variable	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
Gender (male vs. female)	1.68 (0.94–3.01)	0.082	1.75 (0.87–3.54)	0.117	1.77 (0.90–3.49)	0.102
Age/10 year	1.21 (0.98–1.49)	0.079	1.12 (0.86–1.48)	0.402
Size/10 cm	1.34 (1.06–1.68)	0.013	1.42 (1.02–1.97)	0.036	1.61 (1.23–2.11)	0.001
Malignancy grade (high vs. low)	2.00 (0.96–4.15)	0.063	4.16 (1.69–10.24)	0.001	4.38 (1.95–9.88)	< 0.001
Histopathology
Leiomyosarcoma (vs. liposarcoma)	0.73 (0.37–1.45)	0.366	0.60 (0.24–1.53)	0.285
Other (vs. liposarcoma)	0.86 (0.30–2.43)	0.770	1.01 (0.27–3.89)	0.983
Surgical margin (pos. vs. neg.)	2.24 (1.22–4.09)	0.009	2.44 (1.25–4.77)	0.009	2.70 (1.44–5.06)	0.002
RT (yes vs. no)	0.33 (0.17–0.64)	0.001	0.20 (0.09–0.45)	< 0.001	0.21 (0.10–0.45)	< 0.001
Chemotherapy (yes vs. no)	1.41 (0.68–2.93)	0.364	1.56 (0.58–4.22)	0.381

Numbers presented are HR with corresponding 95% percent CI.

CI, confidence interval; HR, hazard ratio; p, from Likelihood ratio test; RPS, retroperitoneal sarcoma; RT, radiotherapy.

Table IV. Potential prognostic factors for metastasis-free survival by simple and multiple Cox regression analysis of 97 RPS patients.

	Univariate		Multivariate		Limited model
Variable	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
Gender (male vs. female)	1.46 (0.77–2.77)	0.248	1.18 (0.54–2.56)	0.677
Age/10 year	1.03 (0.83–1.28)	0.815	1.17 (0.86–1.59)	0.308
Size/10 cm	0.90 (0.67–1.20)	0.471	1.21 (0.85–1.72)	0.287
Malignancy grade (high vs. low)	6.22 (1.91–20.30)	0.002	7.23 (1.99–26.19)	0.003	9.28 (2.78–31.00)	< 0.001
Histopathology
Leiomyosarcoma (vs. liposarcoma)	3.52 (1.78–6.99)	< 0.001	2.38 (0.95–5.98)	0.065
Other (vs. liposarcoma)	1.91 (0.63–5.80)	0.251	1.84 (0.51–6.65)	0.352
Surgical margin (pos. vs. neg.)	0.75 (0.38–1.49)	0.409	0.79 (0.37–1.71)	0.556
RT (yes vs. no)	0.58 (0.30–1.13)	0.111	0.42 (0.20–0.88)	0.021	0.34 (0.17–0.67)	0.002
Chemotherapy (yes vs. no)	1.66 (0.78–3.52)	0.187	1.22 (0.44–3.34)	0.706

Numbers presented are HR with corresponding 95% CI.

CI, confidence interval; HR, hazard ratio; p, from Likelihood ratio test; RPS, retroperitoneal sarcoma; RT, radiotherapy.

Table V. Potential prognostic factors for overall survival by simple and multiple Cox regression analysis of 97 RPS patients.

	Univariate		Multivariate		Limited model
Variable	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
Gender (male vs. female)	1.23 (0.71–2.12)	0.460	1.24 (0.63–2.44)	0.534
Age/10 year	1.31 (1.06–1.61)	0.013	1.45 (1.09–1.94)	0.011	1.44 (1.12–1.84)	0.004
Size/10 cm	1.12 (0.88–1.42)	0.366	1.30 (0.93–1.82)	0.127
Malignancy grade (high vs. low)	2.81 (1.32–5.97)	0.007	3.97 (1.62–9.74)	0.003	3.92 (1.67–9.17)	0.002
Histopathology
Leiomyosarcoma (vs. liposarcoma)	1.46 (0.80–2.65)	0.217	1.33 (0.57–3.14)	0.509
Other (vs. liposarcoma)	1.69 (0.73–3.88)	0.219	2.93 (1.00–8.65)	0.051
Surgical margin (pos. vs. neg.)	1.42 (0.82–2.48)	0.213	1.23 (0.64–2.34)	0.538
RT (yes vs. no)	0.51 (0.29–0.91)	0.022	0.36 (0.18–0.72)	0.004	0.32 (0.17–0.62)	0.001
Chemotherapy (yes vs. no)	1.49 (0.74–3.00)	0.265	2.18 (0.84–5.69)	0.110	2.34 (0.97–5.65)	0.059

Numbers presented are HR with corresponding 95% percent CI.

CI, confidence interval; HR, hazard ratio; p, from Likelihood ratio test; RPS, retroperitoneal sarcoma; RT, radiotherapy.