| Colorectal cancer (CRC) has become the first most common cancer in Taiwan. There is strong evidence that screening for colorectal cancer improves survival. Current international practice guidelines and expert consensus statements recommend colorectal cancer screening for people over 50 years. In reality the risk for colorectal cancer is uneven in the population and varies significantly with gut microbiota, age, gender, smoking, family history, obesity, ethnicity, dietary and other factors. Many studies show gut microbiota play a critical role in the progression of colorectal cancer in recent years. This suggests understanding microbiota dysbiosis during colorectal cancer progression could be used to risk stratify the population. In addition, diarrhea induced by irinotecan chemotherapy is believed to be associated with microbiota dysbiosis. Therefore we performed 16S rRNA amplicon sequencing of paired tissue samples to identify alterations of microbiota involved in colorectal cancer progression and chemotherapy-induced adverse drug reaction. Three genera, Bacteroides, Fusobacterium, and Prevotella, were more abundant in carcinomas compared to paired adenomas and non-neoplastic tissues. The overrepresented microbes in cancer tissues correlated with genomic and/or genetic alterations in CRC. More importantly, with the incorporation of fecal Fusobacterium nucleatum into our previous clinical risk score panel, the detection rate for colorectal advanced neoplasia and tumor for Taiwan subjects is improved. Our results also showed that genera Faecalibacterium and Bifidobacterium were underrepresented in guts of CRC patients with diarrhea after irinotecan treatment when compared to that of CRC patients without diarrhea. These observations may lead to novel approaches for prevention of diarrhea induced by irinotecan treatment. |
