Prognostic impact of diagnosing colorectal neuroendocrine carcinoma using the World Health Organization 2010 classification.
BACKGROUND
Neuroendocrine carcinomas (NECs) arising in the large intestine are rare neoplasms with highly aggressive behavior. The aim of the study was to compare the 2000 and 2010 World Health Organization (WHO) classification of these colorectal NECs.


METHODS
We conducted a retrospective study of patients diagnosed with colorectal NECs according to the WHO 2000 classification who underwent surgery at the Asan Medical Center between May 2000 and December 2010. The data were reevaluated to assess their consistency with the WHO 2010 classification.


RESULTS
For 20 of the 34 patients (59%), the 2000 and 2010 WHO classifications yielded the same NEC diagnosis (NEC group), whereas for 14 of the 34 patients (41%), the WHO 2010 classification mandated a diagnosis of G1 or G2 neuroendocrine tumors (NETs) rather than NECs (G1/G2 NET group). The NEC group was older than the G1/G2 NET group (64 vs 55 years; P = .05). Tumor differentiation in the NEC group was poorer than in the G1/G2 NET group (percentage of poorly differentiated tumor, 70% vs 7%; P < .001). In both groups based on the 7th American Joint Committee on Cancer staging, most of the tumors were advanced at the time of diagnosis, reaching stage IIIB (6 NEC vs 10 NET) and stage IV (10 NEC vs 3 NET). The 5-year overall survival in the 2 groups was different (P = .02), but not the 5-year disease-free survival (P = .24).


CONCLUSIONS
These results indicate that the WHO 2010 classification of colorectal NEC is more accurate and has better prognostic value than the WHO 2000 classification.
Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Jong Lyul
JL
Lee
Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. Electronic address: csyu@amc.seoul.kr.
Chang Sik
CS
Yu
Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Misung
M
Kim
Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Seung-Mo
SM
Hong
Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Seok-Byung
SB
Lim
Department of Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
Jin Cheon
JC
Kim
D000328:Adult; D000368:Aged; D018278:Carcinoma, Neuroendocrine / Q000145:classification* / Q000175:diagnosis* / Q000401:mortality; D003106:Colon / Q000473:pathology; D015179:Colorectal Neoplasms / Q000145:classification* / Q000175:diagnosis* / Q000401:mortality; D004358:Drug Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012007:Rectum / Q000473:pathology; D056910:Republic of Korea; D012189:Retrospective Studies; D015996:Survival Rate; D014944:World Health Organization