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POOR PROGNOSTIC HISTOPATHOLOGICAL FACTORS IN STAGE II COLON CANCER DIFFER FROM THOSE IN RECTAL CANCER.
Lieve G. Leijssen*1,2, Anne M. Dinaux1,2, Hiroko Kunitake1,2, Liliana G. Bordeianou1,2, David L. Berger1,2
1General and Gastrointestinal Surgery, Massachusetts General Hospital, Somerville, MA; 2Harvard Medical School, Boston, MA
Introduction
The decision as to whether or not to give chemotherapy in stage II colorectal cancer is a subject of debate. Several histopathological features have been described as risk factors in this stage of disease. The aim of this study was to evaluate the prognostic value of pathological extramural vascular invasion (EMVI), perineural invasion (PNI) and lymphovascular invasion (LVI) in patients with stage II colon and rectal cancer independently.
Methods
We identified all patients who underwent surgical therapy for stage II colon (CC) and rectal (RC) cancer at a tertiary center between 2004-2014. Recurrence rates, both local (LR) and distant (DR), as well as disease-free (DFS), disease-specific (DSS) and overall survival (OS) were determined using Kaplan-Meier curves and log-rank analysis. Cox proportional hazard ratios (HR) were performed to determine differences in outcomes adjusted for potential confounders. *
Results
A total of 571 patients were included, of whom 442 (77.4%) had CC and 129 (22.6%) RC. Perineural invasion was identified more often in RC than CC (27.1% vs. 14.0%, P<0.001). In CC patients, EMVI, LVI, and PNI were correlated with T4 tumors, bowel obstruction, and distant recurrence (P<0.01). Additionally, CC EMVI+ patients presented more often with abdominal pain and received more adjuvant therapy (P<0.05) than CC EMVI- patients. In rectal cancer, we did not find differences within the groups, except for more anemic patients in the EMVI+ group (P0.028). Kaplan-Meier curves did not demonstrate differences in long-term outcomes between colon and rectal cancer with either EMVI+, PNI+ or LVI+. The estimated 5-year DFS, DSS and OS were worse for all histopathological outcomes within the colon cancer cohort. Conversely, recurrence rates and survival outcomes were all comparable in the RC group. After adjustment, EMVI and PNI were significant factors in OS (HR 1.77; HR 2.12), DSS (HR3.63; HR 2.36), and DFS (HR 2.73; HR 2.46) (P<0.05) in colon cancer. Multivariable analysis demonstrated only EMVI+ as a risk factor for poor DFS (HR 2.30, P0.047) in rectal cancer.
Conclusion
Presence of EMVI, PNI and LVI on pathology was strongly associated with adverse outcomes in stage II colon cancer but had little impact in stage II rectal cancer. Therefore, these histopathological outcomes could complement the current AJCC staging and should be considered when stratifying colon cancer patients for adjuvant treatment.
*Survival outcomes adjusted for age, ASA-score, T-stage, high-grade disease, neoadjuvant treatment, and adjuvant treatment. Recurrence outcomes adjusted for T-stage, high-grade disease, neoadjuvant treatment, and adjuvant treatment.
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