Are colibactin-induced DNA signatures in colorectal cancer linked to the presence of colibactin-producing bacteria at diagnosis?

We analyzed the available evidence and found that colorectal tumors with DNA damage patterns linked to colibactin often do not contain the bacteria that produce it at the time of diagnosis. This suggests the bacteria may have been present earlier, caused damage, and then been cleared by the body before the tumor was detected [1]. The evidence we’ve reviewed so far leans toward the idea that the presence of these DNA signatures does not require the bacteria to still be there when the cancer is diagnosed. Instead, the damage may be a lasting mark left behind after the bacteria are gone. We did not find any studies that contradict this pattern. This means that detecting colibactin-related DNA changes in a tumor could point to past exposure to these bacteria, even if they are no longer present. It also suggests that the timing of bacterial presence matters more than its current presence when assessing risk or damage. Our current analysis shows this pattern is consistent across the evidence we’ve reviewed, but we don’t yet know how long after infection the bacteria are cleared, or why some people’s bodies remove them while others don’t. For now, if you have colorectal cancer and your tumor shows these DNA signatures, it may mean colibactin-producing bacteria were involved earlier in the process — even if they’re not detectable today.