A study of morphological prognostic factors in colorectal cancer and survival analysis

Abstract

Context: Globally, colorectal cancer (CRC) is one of the leading causes of cancer death. Many Asian countries experience an increasing incidence of CRC due to changes in diet and lifestyle. Many pathological prognostic factors other than the tumor-node-metastasis (TNM) staging reflect the biological behavior of tumor tissue and influence the treatment and survival.

Aims: The aim is to evaluate: (1) Various morphological prognostic factors of colorectal cancer, (2) the correlation of the prognostic factors with survival, and (3) the prognostic factors with independent prognostic significance.

Settings and design: Descriptive study conducted in a tertiary care center in Kerala.

Materials and methods: Five hundred and eighty-seven resected specimens of CRC received from January 1, 2007 to October 31, 2012 were studied for various morphological prognostic factors. Overall survival and disease-free survival were obtained by Kaplan Meier survival analysis. Cox regression analysis was performed to identify the predictors of survival.

Results: CRC incidence was higher in the age group 40-60 years and males were dominant. Rectum was the common site with bleeding per rectum as a common symptom. Predominant tumors had ulcerative gross configuration, size ≤5 cm and were free of transverse, radial margin involvement. Majority of tumors were well-differentiated adenocarcinoma with invasion beyond muscularis propria, without vascular, perineural invasion, and lymph node involvement and were in Stage II. The overall and disease-free 3-year survival rates were 89.1% and 88%, respectively. Among the eight significant factors in univariate analysis, tumor histology, depth of invasion, and perineural invasion were found to have independent prognostic significance in multivariate analysis.

Conclusions: In addition to the TNM staging, other morphological prognostic factors should be given importance, while considering the patients for adjuvant therapy to improve the survival rates in CRC.

Keywords: Adjuvant therapy; perineural invasion; prognostic factors; survival; tumor histology.