Goal of this digest is to extract the most interesting information from the paper in question (see reference section at the bottom) and put it into laymen-friendly terms. To make the extracted information easily traceable, I'll follow the segmentation of the original review article in this digest.

'1 Introduction'

About one in nine men and one in twelve women are estimated die to cancer. 90% of these deaths are thought to be due to metastases (secondary cancer colonies, where cancer cells travelled in the blood from the initial tumour to the site of the new colony).

There are primarily two categories of risk-factors to cancer development: endogenous (internally made) and exogenous (externally made). The former we have no control of, the latter we can influence through sensible lifestyle and dietary choices.

The article then has something, which seems self-contradicting. On one hand high-fat diets have epidemiologically (population survey) been linked to cancer progression in some diseases, but ketogenic diets (diets, which rely exclusively on fat for the provision of biochemical energy) have been shown to up-regulate genes, which suppress cancer development. This would seem to me to be due to the fact, that the study, upon which the claim of high-fat diets being bad is based, discussed the obesity-inducing modern standard Western diet, which is indeed high-fat but also high-carbohydrate, which means, that it doesn't induce ketosis (fat-burning). Given the fact that Tang et al. tell us, that high-sugar diets are associated with cancer development, it should be safe to say, that fat itself isn't bad (since it induces ketosis and is the main constituent of ketogenic diets, which are cancer-protective), but that sugar is, whether alone or in combination with fat.

Tang et al. then move on to discuss the prior contradicting evidence for and against high-salt diets being promotive or inhibitive of cancer. It seems, that in some cases a high-salt environment has been found to be promotive of cancer cell survival, and that in other cases a high-salt environment has been found to be promotive of anti-cancer immune cell activity.