Table 5. Stratified Cox proportional hazard model for the risk of death and the associated treatment modalities among recurrent HNSCC patients, considering both recurrent clinical stages and sites.

Recurrence stage	Recurrent site	n	Treatment modality	aHR (95% CI)	n value
Group I
Stage I and II	Nonoral cavity	8	CT alone	1.00
Stage I and II	Nonoral cavity	7	Re-RT alone	0.90 (0.26–3.06)	0.859
Stage I and II	Nonoral cavity	13	CCRT	0.48 (0.17–1.43)	0.188
Stage I and II	Nonoral cavity	64	Surgery ± RT/CT	0.26 (0.10–0.63)	0.003
Group II
Stage I and II	Oral cavity	160	CT alone	1.00
Stage I and II	Oral cavity	71	Re-RT alone	0.62 (0.43–0.89)	0.009
Stage I and II	Oral cavity	325	CCRT	0.68 (0.53–0.86)	0.002
Stage I and II	Oral cavity	1057	Surgery ± RT/CT	0.32 (0.26–0.41)	<0.001
Group III
Stage III and IV	Nonoral cavity	100	CT alone	1.00
Stage III and IV	Nonoral cavity	21	Re-RT alone	0.98 (0.56–1.69)	0.928
Stage III and IV	Nonoral cavity	94	CCRT	0.53 (0.38–0.73)	<0.001
Stage III and IV	Nonoral cavity	251	Surgery ± RT/CT	0.33 (0.25–0.43)	<0.001
Group IV
Stage III and IV	Oral cavity	412	CT alone	1.00
Stage III and IV	Oral cavity	109	Re-RT alone	1.28 (1.01–1.62)	0.041
Stage III and IV	Oral cavity	472	CCRT	0.72 (0.62–0.84)	<0.001
Stage III and IV	Oral cavity	875	Surgery ± RT/CT	0.40 (0.35–0.46)	<0.001

*HRs were adjusted by age, sex, CCI score, clinical stage at first diagnosis, and recurrence-free interval

Abbreviations: CT, chemotherapy; CCRT, concurrent chemoradiotherapy; CCI, Charlson comorbidity index; CI, confidence interval; aHR, adjusted hazard ratio; PY, person-years; RT, radiotherapy.