Radiotherapy as salvage treatment of salivary duct carcinoma in major salivary glands without radical operations

Figures & data

Table 1 Clinicopathological characteristics of all the included patients

Clinical characteristics	Result
Age, average (range), years	58.5 (39–79)
Sex, n (%)
Female	5 (12.5)
Male	35 (87.5)
Smoking history, n (%)
Negative	11 (27.5)
Positive	29 (72.5)
Preoperative symptoms, n (%)
No	28 (70)
Yes	11 (27.5)
Unknown	1 (2.5)
Primary tumor site, n (%)
Submandibular gland	9 (22.5)
Parotid gland	31 (77.5)
Tumor size, average (range), mm, n (%)	27.5 (10–65)
≤25	22 (55.0)
>25	12 (30.0)
Unknown	6 (15.0)
Gross residual disease (primary or lymph node), n (%)
No	26 (65.0)
Yes	14 (35.0)
Adequate surgical margins, n (%)
No	22 (55.0)
Yes	18 (45.0)
Neck dissection, n (%)
No	30 (75.0)
Yes	10 (25.0)
Treatment, n (%)
Follow-up	7 (17.5)
Operation	1 (2.5)
Chemotherapy	2 (5.0)
Radiotherapy	24 (67.5)
Radiotherapy + chemotherapy	3 (7.5)
Operation + radiotherapy	2 (5.0)
Operation + radiotherapy + chemotherapy	1 (2.5)

Table 2 Univariate and multivariable analyses for LRC

Variables	LRC
	Univariate analysis		Multivariate analysis
	χ^2 test	P-value	HR (95% CI)	P-value
Age, years	6.171	0.013		0.077
≤50			1
>50			11.131 (0.769–161.204)
Gender	0.002	0.960		0.470
Female			1
Male			3.037 (0.149–61.826)
Smoking history	0.154	0.694		0.153
No			1
Yes			3.675 (0.616–21.926)
Tumor size, mm	0.094	0.760		0.080
≤25			1
>25			0.104 (0.008–1.313)
Gross residual disease	5.303	0.021		0.047
No			1
Yes			9.499 (1.032–87.406)
Radiotherapy	25.394	0.000		0.010
Yes			1
No			70.567 (2.719–1,831.238)
Remedial surgery	1.930	0.165		0.839
Yes			1
No			0.703 (0.023–21.201)

Notes: Bold figures indicate statistical significant, P<0.05.

Abbreviation: LRC, local–regional control.

Figure 1 Kaplan–Meier analysis of local–regional control of patients with/without radiotherapy (Log-rank tests: χ²=25.394, P=0.000).

Table 3 Univariate and multivariable analyses for DDFS

Variables	DDFS
	Univariate analysis		Multivariate analysis
	χ^2 test	P-value	HR (95% CI)	P-value
Age, years	1.124	0.289		0.918
≤50			1
>50			0.912 (0.155–5.350)
Gender	0.181	0.670		0.098
Female			1
Male			0.113 (0.009–1.500)
Smoking history	1.366	0.243		0.024
No			1
Yes			13.694 (1.412–132.798)
Tumor size, mm	1.750	0.186		0.186
≤25			1
>25			2.747 (0.615–12.279)
Gross residual disease	10.911	0.001		0.029
No			1
Yes			10.592 (1.270–88.346)
Radiotherapy	0.191	0.662		0.367
Yes			1
No			0.441 (0.074–2.610)
Remedial surgery	7.283	0.007		0.050
Yes			1
No			0.065 (0.004–1.000)

Notes: Bold figures indicate statistical significant, P<0.05.

Abbreviation: DDFS, distant disease-free survival.

Figure 2 Kaplan–Meier analysis of distant disease-free survival of patients with/without radiotherapy (Log-rank tests: χ²=0.191, P=0.662).

Table 4 Treatment and prognosis of patients with gross residual disease

	Treatment	Local–regional progression	Time (months)	Distant metastasis	Time (months)
Patient 1	Radiotherapy	No	88	No	88
Patient 2	Radiotherapy	No	12	Yes	7
Patient 3	Chemotherapy	Yes	18	Yes	89
Patient 4	Radiotherapy	No	22	Yes	7
Patient 5	Radiotherapy + chemotherapy	No	15	Yes	12
Patient 6	Radiotherapy	Yes	9	No	13
Patient 7	Radiotherapy	No	10	Yes	3
Patient 8	Operation + radiotherapy	Yes	40	Yes	16
Patient 9	Operation + radiotherapy	No	40	Yes	40
Patient 10	Operation	Yes	8	No	10
Patient 11	Operation + radiotherapy + chemotherapy	No	12	Yes	4
Patient 12	Follow-up	Yes	12	Yes	60
Patient 13	Radiotherapy	No	13	Yes	1
Patient 14	Follow-up	Yes	23	No	26