Disparities in prostate cancer screening, diagnoses, management, and outcomes between Indigenous and non-Indigenous men in a universal health care system.

BACKGROUND: Indigenous Peoples have higher morbidity rates and lower life expectancies than non-Indigenous Canadians. Identification of disparities between Indigenous and non-Indigenous men regarding prostate cancer (PCa) screening, diagnoses, management, and outcomes was sought. METHODS: An observational cohort of men diagnosed with PCa between June 2014 and October 2022 was studied. Men were prospectively enrolled in the province-wide Alberta Prostate Cancer Research Initiative. The primary outcomes were tumor characteristics (stage, grade, and prostate-specific antigen [PSA]) at diagnosis. Secondary outcomes were PSA testing rates, time from diagnosis to treatment, treatment modality, and metastasis-free, cancer-specific, and overall survivals. RESULTS: Examination of 1,444,974 men for whom aggregate PSA testing data were available was performed. Men in Indigenous communities were less likely to have PSA testing performed than men outside of Indigenous communities (32 vs. 46 PSA tests per 100 men [aged 50-70 years] within 1 year; p < .001). Among 6049 men diagnosed with PCa, Indigenous men had higher risk disease characteristics: a higher proportion of Indigenous men had PSA ≥ 10 ng/mL (48% vs. 30%; p < .01), TNM stage ≥ T2 (65% vs. 47%; p < .01), and Gleason grade group ≥ 2 (79% vs. 64%; p < .01) compared to non-Indigenous men. With a median follow-up of 40 months (interquartile range, 25-65 months), Indigenous men were at higher risk of developing PCa metastases (hazard ratio, 2.3; 95% CI, 1.2-4.2; p < .01) than non-Indigenous men. CONCLUSIONS: Despite receiving care in a universal health care system, Indigenous men were less likely to receive PSA testing and more likely to be diagnosed with aggressive tumors and develop PCa metastases than non-Indigenous men.

A Novel 2D Probability Density Function Integrating the Rectal Motion and Wall Thickness in Prostate IMRT.

BACKGROUND AND PURPOSE: This study investigated the variations of rectal motion and wall thickness in prostate intensity-modulated radiotherapy using a novel 2D probability density function. To evaluate the impact of the position, thickness, and deformation of the rectum on the dose distribution in prostate intensity-modulated radiotherapy plans, probability density functions (pdf) of the deformation of rectal cross-section (DW), rectal dose distribution (RM), and changes in rectal wall thickness (TW) were used in the planning optimization. MATERIALS AND METHODS: The problem of approximating the product of a number of Gaussian mixture distributions arises in the number of parameters describing the specific mean value, standard deviation, and weight in every Gaussian. In this work, a pdf model has been developed which specifies the variability of the average rectal wall thickness. The model is based on the histogram of 587 randomly selected patients with prostate cancer. RESULTS: The average wall thicknesses were determined based on the rectal structure contours drawn on the planning CT image set of the patient. The pdf describing the variability of the rectal wall thickness (pdfTW) is represented as a three-mode Gaussian mixture of specific (µF,σF); (µPF,σPF) and (µE,σE) and individual weights (wF, wPF, and wE) representing full, partially full, and empty rectal states, respectively. CONCLUSION: A 2D Gaussian pdf of rectal motion and rectal thickness (2D pdfM&TW) function, as a product-mixture model of the pdf of the rectal motion (pdfM) and the pdfTW, was developed using published and experimental data, respectively, and presented mathematically. Using correlation values between the functions pdfM and pdfTW, the sensitivity of profiles and projections to the 2D pdfM&TW is numerically demonstrated.