Synchronous and metachronous colorectal cancers: distinct disease entities or different disease courses?
OBJECTIVE
This study aimed to investigate the clinicopathological characteristics of synchronous and metachronous colorectal cancers (CRCs).


METHODS
From January 1, 2001 to December 31, 2010, 5898 patients who underwent surgical resection for CRCs were enrolled. Synchronous CRC was defined as presence of more than one primary CRC within 6 months of resection of the primary tumor; while CRC that occurred at least 6 months later was regarded as metachronous CRC.


RESULTS
5346 patients were eligible for the study and divided into three groups: solitary, synchronous and metachronous CRC. The overall prevalence of the synchronous CRC was 2.2% and the 10-year cumulative incidence of metachronous cancer was 0.84%. 29 (64%) metachronous cancers were diagnosed within 3 years of the index cancer and the mean time interval was 3.2 years. Male gender and presence of associated adenoma were significant risk factors for both synchronous and metachronous CRC. Synchronous and metachronous CRC patients shared similar clinicopathological features except that the former were older than the latter by 3.7 years. The five-year survival rates were not different among the three groups.


CONCLUSIONS
Our study indicates that synchronous and metachronous CRC might represent similar disease entity with different courses.
Chih-Sheng
CS
Huang
Shung-Haur
SH
Yang
Chun-Chi
CC
Lin
Yuan-Tsiu
YT
Lan
Shin-Ching
SC
Chang
Huann-Sheng
HS
Wang
Wei-Shone
WS
Chen
Tzu-Chen
TC
Lin
Jen-Kou
JK
Lin
Jeng-Kai
JK
Jiang
D000236:Adenoma / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000473:pathology* / Q000601:surgery; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D016609:Neoplasms, Second Primary / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan; D013997:Time Factors