The significant survival advantage of female sex in nasopharyngeal carcinoma: a propensity-matched analysis.
BACKGROUND
Whether females have better survival than males in nasopharyngeal carcinoma is barely acknowledged and the exact explanations remain unknown.


METHODS
Overall, 5929 patients receiving treatment between January 2005 and December 2010 were separately stratified by stage into early and advanced stage groups, and by age into premenopausal (⩽45 years), menopausal (46-54 years) and postmenopausal (⩾55 years) groups. Matched males and females in each group were identified using the propensity score matching method. Differences in disease-free survival (DSS), overall survival (OS), distant metastasis-free survival (DMFS) and locoregional relapse-free survival (LRFS) were estimated by the Kaplan-Meier method and Cox regression model.


RESULTS
Overall, 398, 923, 744, 319 and 313 pairs of males and females were matched in early stage, advanced stage, premenopausal, menopausal and postmenopausal group, respectively. Females showed significant advantage over males across all end points in both early and advanced stage groups (P⩽0.042). However, this advantage persisted at premenopausal age (P⩽0.042), declined during menopause (DMFS, P=0.021; DSS, P=0.100; OS, P=0.693; LRFS, P=0.330) and totally disappeared at postmenopausal age (P⩾0.344).


CONCLUSIONS
Sex significantly affects NPC survival, with a definite female advantage regardless of tumour stage. Intrinsic biologic traits appear to be the exact explanation according to the declining magnitude of sex effect with age.
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
P-Y
PY
OuYang
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
L-N
LN
Zhang
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
X-W
XW
Lan
Department of Neurology, Jiangxi Provincial People's Hospital, Nanchang, Jiangxi, China.
C
C
Xie
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
W-W
WW
Zhang
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
Q-X
QX
Wang
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
Z
Z
Su
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
J
J
Tang
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, No. 651 Dongfeng Road East, Guangzhou, 510060 Guangdong, China.
F-Y
FY
Xie
D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002277:Carcinoma; D059248:Chemoradiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D009367:Neoplasm Staging; D011379:Prognosis; D057216:Propensity Score; D012189:Retrospective Studies; D012737:Sex Factors; D015996:Survival Rate