Elevated systemic interleukin-7 in patients with colorectal cancer and individuals at high risk of cancer: association with lymph node involvement and tumor location in the right colon

Interleukin (IL)-7 is a cytokine essential for protective immunity, and it is considered as a promising agent for cancer immunotherapy. Recent studies, however, appear to associate IL-7 with aggressiveness of solid tumors. The IL-7 has been less studied in colorectal cancer (CRC) and conditions associated with increased risk of CRC development. To explore IL-7 status in bowel diseases, it was measured immunofluorometrically in 431 individuals (110 with CRC) by using Luminex platform. A level of IL-7 in CRC patients was significantly higher than in controls, did not differ from those with adenomas, but was lower than in both active and inactive inflammatory bowel disease (IBD) cases. In CRC, IL-7 was higher in patients with lymph node and distant metastases and with tumors located in right colon. In adenomas, IL-7 elevation was associated exclusively with villous growth pattern, while in IBD, circulating IL-7 reflected clinical activity of Crohn’s disease and ulcerative colitis. Systemic TNFα, IL-10, and PDGF-BB were independent predictors of circulating IL-7. In summary, our study is the first to demonstrate IL-7 elevation in CRC in association with metastatic disease and tumor location. Both associations should be considered when designing IL-7-based immunotherapies for CRC. Further studies on IL-7 functionality in CRC are necessary.