The Brazilian national prospective active surveillance (AS) cohort of patients with low-risk prostate cancer in the public health system: vigiaSUS study protocol.

BACKGROUND: Prostate cancer exhibits a very diverse behaviour, with some patients dying from the disease and others never needing treatment. Active surveillance (AS) consists of periodic PSA assessment (prostate-specific antigen), DRE (digital rectal examination) and periodic prostate biopsies. According to the main guidelines, AS is the preferred strategy for low-risk patients, to avoid or delay definitive treatment. However, concerns remain regarding its applicability in certain patient subgroups, such as African American men, who were underrepresented in the main cohorts. Brazil has a very racially diverse population, with 56.1% self-reporting as brown or black. The aim of this study is to evaluate and validate the AS strategy in low-risk prostate cancer patients following an AS protocol in the Brazilian public health system. METHODS: This is a multicentre AS prospective cohort study that will include 200 patients from all regions of Brazil in the public health system. Patients with prostate adenocarcinoma and low-risk criteria, defined as clinical staging T1-T2a, Gleason score ≤ 6, and PSA < 10 ng/ml, will be enrolled. Archival prostate cancer tissue will be centrally reviewed. Patients enrolled in the study will follow the AS strategy, which involves PSA and physical examination every 6 months as well as multiparametric MRI (mpMRI) every two years and prostate biopsy at month 12 and then every two years. The primary objective is to evaluate the reclassification rate at 12 months, and secondary objectives include determining the treatment-free survival rate, metastasis-free survival, and specific and overall survival. Exploratory objectives include the evaluation of quality of life and anxiety, the impact of PTEN loss and the economic impact of AS on the Brazilian public health system. DISCUSSION: This is the first Brazilian prospective study of patients with low-risk prostate cancer under AS. To our knowledge, this is one of the largest AS study cohort with a majority of nonwhite patients. We believe that this study is an opportunity to better understand the outcomes of AS in populations underrepresented in studies. Based on these data, an AS national clinical guideline will be developed, which may have a beneficial impact on the quality of life of patients and on public health. TRIAL REGISTRATION: Clinicaltrials registration is NCT05343936.

Mouse model of diethylnitrosamine-induced gastric cancer.

BACKGROUND: Nitrosamines are associated with the potential to induce cancer in the digestive tract. Ethanol has also been shown to enhance the effects of nitrosamine-induced carcinogenesis. The aim of this study was to investigate a murine model of the prevalence and types of epithelial lesions induced in the stomach by diethylnitrosamine (DEN), and to evaluate the influence of ethanol and N'-nitrosonornicotine (NNN) as promoters of gastric carcinogenesis. MATERIALS AND METHODS: Two hundred eight (n = 208) mice were distributed into five groups and administered either water (G1), DEN+water (G2), DEN+NNN (G3), DEN+Ethanol (G4), or DEN+NNN+Ethanol (G5) for a period of 180 days. Mice were sacrificed; their stomachs were sectioned and stained with hematoxylin/eosin. Stomachs were analyzed for normal histology; foveolar hyperplasia; gastritis; ulcer; adenoma; metaplasia; dysplasia; squamous-cell cancer (SCC); and adenocarcinoma (ACA). RESULTS: One hundred eighty-four (N = 184) specimens were studied. No statistically significant differences were observed between the average DEN consumption of groups (P > 0.05). Unlike G1, in all four groups exposed to carcinogens, gastric SCC and ACA were induced (P < 0.001). SCC was identified in 91 (49.5%) and ACA in 77 (41.8%) of all mice (including controls). In 47 mice (25.5%), we identified two histological types of carcinoma that occurred simultaneously. The prevalence of ACA in G5 was higher when compared with the other exposed groups (P < 0.001). CONCLUSIONS: We created an optimal murine model for investigation of the development of gastric carcinogenesis, as there was a high rate of development of tumors, but low mortality and morbidity. The coadministration of DEN, ethanol, and NNN induced carcinogenesis to the largest extent compared with the other combinations.