Lower survival after right-sided versus left-sided colon cancers: Is an extended lymphadenectomy the answer?
Introduction
There is an increase in the incidence of right-sided colon cancer [1,2]. There are certain important differences between right- and left-sided cancers. Tumors located in the proximal colon tend to occur in older patients, present with more advanced stages, and have mucinous histology and poor differentiation [3]. There are also important molecular biological differences [4]. However, the effect of these differences and the tumor location within the colon has not been well described. Past studies have generally demonstrated worse outcomes for proximal colon cancers compared to more distal lesions, but many of these studies have been limited to single centre studies with relatively small sample sizes or have used study cohorts before the introduction of modern chemotherapy regimens [5].
Tumour location may affect oncologic outcomes for colon adenocarcinoma due to different levels of vascular ligation and nodal harvest, but the data are equivocal [6,7]. For left-sided cancers, a high vascular ligation of the inferior mesenteric artery is often performed, whereas routine high ligation of the ileocolic pedicle (i.e. D3 dissection) is not performed in right-sided cancers. This may result in different nodal harvest patterns between the proximal and distal cancers [8], which may have prognostic implications. Therefore, the objective of this study is to determine the effect of tumor location and lymph node yield on overall survival(OS) in stage I-III colon adenocarcinoma.
Section snippets
Data source & study subjects
The National Cancer Database (NCDB) is a cancer registry sponsored by the American College of Surgeons, the Commission on Cancer (CoC), and the American Cancer Society. It includes approximately 70% of all new cancer diagnoses in the United States consisting of over 1 million new cases per year form 1500 hospitals [9]. All Commission on Cancer accredited hospitals are required to include all new cancer diagnoses to the NCDB. Data is entered based on the CoC facility oncology registry standards
Results
A total of 504,958 patients were eligible and included in this study, of which 231,760 were left-sided tumors and 273,198 were right-sided tumors. Patient and facility characteristics in the unmatched cohort are shown in Table 1, and tumor and treatment characteristics are shown in Table 2. There were significant differences between right- and left-sided tumors for all variables. After matching, 148,540 patients were included in each group (Table 1, Table 2). There were no significant
Discussion
Tumor location within the colon may have prognostic implications. The results of the present study demonstrate that long-term oncologic outcomes for right-sided colon cancers are inferior to those of left-sided lesions, but this negative effect may be mitigated if a higher lymph node harvest is obtained.
Past studies on the effect of tumor location on oncologic outcomes have been equivocal. A meta-analysis 15 studies by Yahagi et al. reported worse OS for right-sided cancers (pooled HR 1.14, 95%
Funding source
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of interest
None.
Funding information
None.
References (25)
- et al.
The worse prognosis of right-sided compared with left-sided colon cancers: a systematic review and meta-analysis
J. Gastrointest. Surg.
(2016) - et al.
Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases
J. Clin. Epidemiol.
(1992) - et al.
Skip metastases in colon cancer: assessment by lymph node mapping using molecular detection
Surgery
(2001) - et al.
The value of pre-operative computed tomography scanning for the assessment of lymph node status in patients with colon cancer
Eur. J. Surg. Oncol.
(2014) - et al.
Is proliferative colonic disease presentation changing?
World J. Gastroenterol.
(2012) - et al.
Proximal shift of colorectal cancer in the Australian Capital Territory over 20 years
Aust. N. Z. J. Med.
(2000) - et al.
The impact of tumor location on the histopathologic expression of colorectal cancer
J BUON
(2006) - et al.
Comparative molecular analyses of left-sided colon, right-sided colon, and rectal cancers
Oncotarget
(2017) - et al.
The rationale behind complete mesocolic excision (CME) and a central vascular ligation for colon cancer in open and laparoscopic surgery : proceedings of a consensus conference
Int. J. Colorectal Dis.
(2014) - et al.
Lymph node evaluation and survival after curative resection of colon cancer: systematic review
J. Natl. Cancer Inst.
(2007)