Lesser prevalence of polyps/WNT-dysregulation and concomitant upregulation of gamma-catenin/MYC point to alternate pathways in colorectal cancer in India.

Colorectal cancer (CRC) is known to follow adenoma carcinoma sequence (ACS) in majority of the tumors and the driver variants and associated pathways are well delineated. However, most of the published data are from the west and information in other ethnicities is sparse. We therefore comprehensively evaluated the CRC tumors from Indian ethnicity for the prevalence of ACS. In this cohort study, clinical data of 100,497 patients who attended hospital between 2013 and 2018 were accessed. Tumors from patients (n = 130) with CRC who were treated primarily by surgery were included. DNA and RNA were isolated to assess variants (direct sequencing) and WNT-pathway dysregulation in genes related to ACS. Global gene expression was generated and analyzed on microarrays (Affymetrix; N = 10) and next generation sequencing platforms (Illumina; N = 25). Gene expression at mRNA (qRT-PCR) and protein level (IHC) of JUP/CTNNB1/MYC were assessed. Correlation between expression of JUP and MYC was evaluated by Karl Pearson's correlation coefficient. The prevalence of polyps was 16.75%, while 18.26% variants in APC/CTNNB1, 20.00% in KRAS, and 18.33% WNT dysregulation were noted. Interestingly, 29/60 (48.33%) tumors showed only MYC upregulation with normal APC/CTNNB1 expression. Global gene expression and validation in an independent tumor cohort confirmed concomitant upregulation of JUP (gamma-catenin) & MYC (r = 0.71; p = 0.001) at mRNA and protein in sizeable number of tumors (45/96; 46.88%). Our study provides evidence for limited prevalence of ACS in the Indian ethnicity. Preventive colonoscopies for early identification and management of CRC may not be an effective strategy in this ethnicity.

Indocyanine green guided sentinel lymph node biopsy may have a high sensitivity for early (T1/T2) colon cancer: A prospective study in Indian patients.

Objectives: Indocyanine green (ICG) dye guided near infrared fluorescence (NIR) imaging is a promising tool for mapping lymphatics. The aim of this study was to evaluate the role of ICG guided SLN biopsy in Indian colon cancer patients. Material and Methods: Forty-eight patients of clinically staged T1-T3 node negative colon cancer underwent laparoscopic/open resection. Patients received colonoscopic peritumoral submucosal ICG injections for laparoscopic (n= 32) and subserosal injections for open resections (n= 16) followed by the detection of SLN using NIR camera. SLNs underwent conventional hematoxylin and eosin (H & E) staging with additional serial sectioning and immunohistochemistry for pancytokeratin antibody (ultra-staging). Detection rate and upstaging rate were the primary end points. Results: Forty-eight patients were recruited. An average of 2.08 ± 1.27 SLNs were identified in 45 patients at a mean time of 8.2 ± 3.68 minutes with a detection rate of 93.75%. Mean age and mean BMI were 59.7 ± 12.54 years and 24.8 ± 4.09 kg/m2 , respectively. Eighteen patients had node positive disease, and SLN was false negative in four of these patients resulting in a sensitivity of 77.77% with a trend towards higher sensitivity for T1-T2 tumours (90% vs. 62.5%, p= 0.068). Upstaging rate was 10%. Negative predictive value (NPV) and accuracy of the procedure were 87.09% and 91.11%, respectively. Conclusion: ICG guided SLN biopsy can identify metastatic lymph nodes in colon cancer patients that can be missed on H & E staging with relatively higher sensitivity for early (T1/T2) tumours.