Benefit of primary tumor resection in stage IV colorectal cancer with unresectable metastasis: a multicenter retrospective study using a propensity score analysis.
OBJECTIVE
Retrospective studies have shown that primary tumor resection improves the prognosis of patients with colorectal cancer (CRC) with unresectable metastasis (mCRC). The aim of this study was to investigate the prognostic impact of primary tumor resection in various subgroups of mCRC patients.


METHODS
A total of 1982 patients with mCRC from January 1997 to December 2007 were retrospectively evaluated. The impact of primary tumor resection on cancer-specific survival (CSS) was analyzed using propensity score analysis to mitigate selection bias. Covariates in the models for propensity scores included treatment period, age, gender, tumor location, depth, lymph node metastasis, number of metastatic organs, and carcinoembryonic antigen (CEA) levels.


RESULTS
Among the whole patient population, primary tumor resection significantly improved CSS [hazard ratio (HR) 0.46, 95% confidence interval (CI) 0.32-0.66, p < 0.01]. However, primary tumor resection did not significantly improve CSS in the following subgroups: patients treated in the first 5 years of the study (HR 0.56, 95% CI 0.28-1.13, p = 0.08), patients aged >65 years (HR 0.72, 95% CI 0.36-1.42, p = 0.31), female patients (HR 0.60, 95% CI 0.31-1.17, p = 0.13), patients with right-sided colon cancer (HR 0.68, 95% CI 0.39-1.20, p = 0.17), and patients without nodal involvement (HR 0.54, 95% CI 0.25-1.17, p = 0.09).


CONCLUSIONS
Our study suggests that primary tumor resection improves the survival of patients with mCRC. However, the prognostic benefit is different among patient subpopulations.
Department of Surgical Oncology, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Soichiro
S
Ishihara
Takeshi
T
Nishikawa
Toshiaki
T
Tanaka
Junichiro
J
Tanaka
Tomomichi
T
Kiyomatsu
Kazushige
K
Kawai
Keisuke
K
Hata
Hioaki
H
Nozawa
Shinsuke
S
Kazama
Hironori
H
Yamaguchi
Eiji
E
Sunami
Joji
J
Kitayama
Kenichi
K
Sugihara
Toshiaki
T
Watanabe
D000367:Age Factors; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D057216:Propensity Score; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012737:Sex Factors
D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen