Primary signet-ring carcinoma (SRC) of the lung: a population-based epidemiologic study of 262 cases with comparison to adenocarcinoma of the lung.
BACKGROUND
The presence of signet-ring cell component has been described as a prominent feature of EML4-ALK positive non-small cell lung cancer. We investigated the clinicopathologic features and survival outcome of primary signet-ring carcinoma (SRC) of the lung with comparison to adenocarcinoma of the lung.


METHODS
Retrospective population-based analysis of histologically diagnosed primary SRC of the lung in the California Cancer Registry between 1989 and 2006 with comparison with adenocarcinoma of the lung.


RESULTS
Two hundred sixty-two histologically diagnosed primary SRC of the lung were compared to 50,089 patients with lung adenocarcinoma. Patients with primary SRC of the lung were significantly younger than patients with adenocarcinoma, with a significantly higher proportion of poorly differentiated tumor and stage IV disease. There was no difference in the distribution of gender and ethnicity among patients with SRC when compared to patients with adenocarcinoma. Subset analysis of patients with available smoking status revealed never smokers comprised a significantly higher proportion of patients with SRC (30.8%) when compared to patients with adenocarcinoma (11.0%; p = 0.0013). Never smokers with SRC tended to be younger with a trend to improved survival (median age = 55 years, median overall survival [OS] = 8 months) than ever smokers with SRC (median age = 59 years, median OS = 4.5 months). Patients with SRC had decreased OS (versus adenocarcinoma; unadjusted hazard ratio = 1.507; 95% confidence interval: 1.326-1.714; p < 0.0001) and was an independent unfavorable prognostic factor by multivariate analysis (versus adenocarcinoma, hazard ratio 1.214, 95% confidence interval: 1.068-1.381; p = 0.0030).


CONCLUSIONS
Primary SRC of the lung is a rare subtype of adenocarcinoma, carries a worse prognosis when compared to adenocarcinoma and shares many of the recently identified clinicopathologic characteristics ascribed to EML4-ALK positive non-small cell lung cancer.
Chao Family Comprehensive Cancer Center, Division of Hematology/Oncology, Department of Medicine, University of California, Irvine Medical Center, Orange, California 92868-3298, USA. Ignatius.ou@uci.edu
Sai-Hong Ignatius
SH
Ou
Argyrios
A
Ziogas
Jason A
JA
Zell
D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D000231:Adenocarcinoma, Papillary / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D018267:Carcinoma, Acinar Cell / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D018279:Carcinoma, Signet Ring Cell / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008175:Lung Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult
C522504:EML4-ALK fusion protein, human; D015514:Oncogene Proteins, Fusion