Tumour infiltrating lymphocytes in colorectal cancers- correlation with tumour biology and clinical outcome- a cohort study

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Objective: To evaluate the pattern of tumour infiltrating lymphocytes in colorectal cancers, and to correlate them with nuclear protein Ki67, vascular endothelial growth factor and clinical outcome.

Method: The retrospective study was conducted at the Nuclear Institute of Medicine and Radiotherapy and the Liaquat University of Medical and Health Sciences, Jamshoro, Pakistan, and comprised data of colorectal cancer patients from January 1, 2008, to December 31, 2018. Whole tumour sections of colorectal cancer were used with hematoxylin and eosin staining, Histological type, grade and infiltrated lymphocytes within the tumour block were assessed.  Ki67 and vascular endothelial growth factor were evaluated by immunohistochemistry, while the staining of these biomarkers was assessed by the percentage of cells stained. Data was analysed using SPSS 22.

Results: Of the 201 patients, 110(54.7%) were males and 91(45.3%) were females. Overall median age was 43 years (range 10-85 years). Majority of the tumours 132(65.7%) showed mild to moderate tumour infiltrating lymphocytes, 30(14.9%) had severe tumour infiltrating lymphocytes, while 39(19.4%) did not show any infiltrating lymphocytes. Tumour infiltrating lymphocytes did not show significant association with the histological grade (p>0.05), but high tumour infiltrating lymphocytes were associated with poor survival without being significantly associated with Ki67 pattern and vascular endothelial growth factor (p>0.05).

Conclusion: Majority of colorectal cancer cases showed varying levels of lymphocyte infilteration, and tumour infiltrating lymphocytes were associated with poor survival, without having significant association with Ki67 pattern and vascular endothelial growth factor.

Key words: Angiogenesis markers, colorectal cancers, Formalin, Immunohistochemistry, Lymphocytes, Tumour infiltrating.