Gender disparities in metastatic colorectal cancer survival.
OBJECTIVE
Previous studies have shown that estrogen prevents colon cancer in postmenopausal women, indicating a role in colorectal cancer carcinogenesis and tumor progression. We investigated the interactions between sex, age, ethnicity, and year of diagnosis on overall survival (OS) in patients with metastatic colorectal cancer (MCRC).


METHODS
We screened 52,882 patients with MCRC from 1988 to 2004, using the Surveillance Epidemiology and End Results registry. Age at diagnosis, sex, ethnicity, tumor location, year of diagnosis, OS, and cancer-specific survival were evaluated using Cox proportional hazards model. The models were adjusted for marital status, tumor site, tumor differentiation, and treatment with radiation and/or surgery.


RESULTS
We observed that younger women (18-44 years old) with MCRC lived longer than younger men (17 months versus 14; P < 0.0001, log-rank test). In contrast, older women (55 years and older) had significantly worse OS than older men (7 months versus 9; P < 0.0001, log-rank test). In multivariate analysis, we found that gender discrepancies have widened in recent years; young women diagnosed after 2000 have improved cancer-specific survival, compared to men (hazard ratio, 0.778; 95% confidence interval, 0.669-0.904), but those diagnosed before 2000 benefit less (hazard ratio, 0.931; 95% confidence interval, 0.821-1.056).


CONCLUSIONS
As one of the largest data sets analyzed to establish that younger women with MCRC survive longer than younger men, hormonal status not only seems to play an important role in the development and pathogenesis of colorectal cancer but also may be of prognostic significance. These data warrant further studies to determine the role of estrogen in colorectal cancer.
Division of Medical Oncology and Department of Preventive Medicine, Keck School of Medicine, University of Southern California/Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA 90033, USA.
Andrew
A
Hendifar
Dongyun
D
Yang
Felicitas
F
Lenz
Georg
G
Lurje
Alexandra
A
Pohl
Cosima
C
Lenz
Yan
Y
Ning
Wu
W
Zhang
Heinz-Josef
HJ
Lenz
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D018426:SEER Program; D012727:Sex Characteristics