That quote is the second sentence in the abstract and the next sentence is:

However, the impact of ketogenic diets (KDs), which contain even higher lipid content but reduce circulating insulin and induce ketogenesis, remains poorly understood.

I read that as saying existing science says high-fat diets that cause you to become obese increase the risk of cancer in the small intestine. Not anything about their findings in this study specifically.

The end of the abstract says:

These findings reveal that dietary lipid content, through fatty acid oxidation rather than ketone metabolism, influences intestinal tumorigenesis and highlight the need for nuanced consideration of dietary strategies for cancer prevention in genetically susceptible populations.

Which I think is implying that they found some difference between their "high-fat" (60% lard diet) and "ketogenic" (80% lard diet) cohorts.

I can't find the full content of the paper to verify exactly what they're trying to say, but I think the only claims they're trying to make are basically, 'there's no point in consuming externally synthesized ketones'. Which, yeah, but good to have proper scientific confirmation.

Just a quick clarification. This is a mouse study. This is not a study in humans.

What do mice eat? What do humans eat? Are we closely related to mice? Do we occupy the same niche? No. This tells us about mice eating a ketogenic diet, not about humans doing so.

Monkeys exaggerate, mice lie. Something shown in primates is likely, though not guaranteed, to be similar in humans, though the degree may be very different. Something shown in mice may or may not replicate in humans at all, and the degree is often very different even if it does.

Mouse studies are great in some ways. They are cheap, fast, and very well understood. You can copy the study design from someone else and save a lot of effort designing your study. You can control for really specific factors by choosing what specific mice you use. You can control their diet perfectly, use large numbers at low cost, and see their full life cycle in just a couple of years.

Mouse studies also suck in a bunch of ways. Humans are not mice, so translating the research is not easy or reliable. Something that causes an issue in mice may or may not translate to humans for a bunch of reasons. They make their own vitamin C for example, so you may have to knock out their genes for making vitamin C if you want to make them get scurvy. You have to humanise them and these changes are always approximations.

So this study does show that a high fat diet that causes obesity IN MICE does increase tumorgenesis in the small intestine. In mice. Not in humans. Every claim here needs that caveat to be made clearly and directly. If they do a translational study in humans I will happily read it, but this study? To me it is worse than useless. It is irrelevant at best and misleading at worst.