Phytosterols and phytostanols are natural products present in vegetable oils, nuts, and seeds, or added to consumer food products whose intake is inversely associated with incidence and prognosis of several cancers. Randomized cancer prevention trials in humans are unfeasible due to time and cost yet the cellular processes and signaling cascades that underpin anti-cancer effects of these phytochemicals have been explored extensively in vitro and in preclinical in vivo models. Here we have performed an original systematic review, meta-analysis, and qualitative interpretation of literature published up to June 2020. MEDLINE, Scopus, and hand-searching identified 408 unique records that were screened leading to 32 original articles that had investigated the effects of phytosterols or phytostanols on cancer biology in preclinical models. Data was extracted from 22 publications for meta-analysis. Phytosterols were most commonly studied and found to reduce primary and metastatic tumor burden in all cancer sites evaluated. Expression of pAKT, and markers of metastasis (alkaline phosphatase, matrix metalloproteases, epithelial to mesenchymal transcription factors, lung and brain colonization), angiogenesis (vascular endothelial growth factor, CD31), and proliferation (Ki67, proliferating cell nuclear antigen) were consistently reduced by phytosterol treatment in breast and colorectal cancer. Very high dose treatment (equivalent to 0.2–1 g/kg body weight not easily achievable through diet or supplementation in humans) was associated with adverse events including poor gut health and intestinal adenoma development. Phytosterols and phytostanols are already clinically recommended for cardiovascular disease risk reduction, and represent promising anti-cancer agents that could be delivered in clinic and to the general population at low cost, with a well understood safety profile, and now with a robust understanding of mechanism-of-action. Graphical Abstract

Triple negative breast cancer (TNBC) is challenging to treat successfully because targeted therapies do not exist. Instead, systemic therapy is typically restricted to cytotoxic chemotherapy, which fails more often in patients with elevated circulating cholesterol. Liver x receptors are ligand-dependent transcription factors that are homeostatic regulators of cholesterol, and are linked to regulation of broad-affinity xenobiotic transporter activity in non-tumor tissues. We show that LXR ligands confer chemotherapy resistance in TNBC cell lines and xenografts, and that LXRalpha is necessary and sufficient to mediate this resistance. Furthermore, in TNBC patients who had cancer recurrences, LXRalpha and ligands were independent markers of poor prognosis and correlated with P-glycoprotein expression. However, in patients who survived their disease, LXRalpha signaling and P-glycoprotein were decoupled. These data reveal a novel chemotherapy resistance mechanism in this poor prognosis subtype of breast cancer. We conclude that systemic chemotherapy failure in some TNBC patients is caused by co-opting the LXRalpha:P-glycoprotein axis, a pathway highly targetable by therapies that are already used for prevention and treatment of other diseases.

Integrated assessment of tumour genomics and immune biomarkers may improve prognostic stratification in non-small cell lung cancer (NSCLC). We examined the distribution and prognostic relevance of somatic pathogenic/likely pathogenic variants (PVs), somatic copy-number alterations (SCNAs), programmed death-ligand 1 (PD-L1) expression and tumour-infiltrating lymphocytes (TILs) in a multicentre cohort. This retrospective, multicentre study included 367 unselected patients with histologically confirmed NSCLC treated at 19 centres in Greece between 2000 and 2020. Targeted next-generation sequencing (NGS) was performed in 267 tumours; PD-L1 tumour proportion score (TPS) and haematoxylin and eosin (H&E)-based TIL density were evaluated in 298 and 352 tumours, respectively. Overall survival (OS) was assessed using Kaplan–Meier and multivariable Cox regression analyses. TP53 (53.6%) and KRAS (16.5%) were the most frequently detected genes with PVs; SCNAs were identified in 22.5% of sequenced tumours and were more frequent in squamous than non-squamous histology. In multivariable analysis (254 complete cases), TIL density ≥10% (hazard ratio [HR] 0.72, 95% confidence interval [CI] 0.52–0.99; p = 0.042) and ≥2 mutated genes (HR 1.44, 95% CI 1.08–1.92; p = 0.014) were independently associated with OS. PIK3CA-containing copy-number gains were significantly enriched in squamous tumours with low TIL density (p = 0.024), while FGFR1-containing copy-number gains showed a similar but non-significant trend (p = 0.088). In the present retrospective study, co-mutation burden and TIL density provided complementary prognostic information beyond clinicopathological variables in NSCLC. The association between selected copy-number gains and an immune-poor squamous phenotype warrants prospective validation.