  This study examines the effect of COVID-19 pandemic and associated lockdowns
on access to crucial diagnostic procedures for breast cancer patients,
including screenings and treatments. To quantify the impact of the lockdowns on
patient outcomes and cost, the study employs a mathematical model of breast
cancer progression. The model includes ten different states that represent
various stages of health and disease, along with the four different stages of
cancer that can be diagnosed or undiagnosed. The study employs a natural
history stochastic model to simulate the progression of breast cancer in
patients. The model includes transition probabilities between states, estimated
using both literature and empirical data. The study utilized a Markov Chain
Monte Carlo simulation to model the natural history of each simulated patient
over a seven-year period from 2019 to 2025. The simulation was repeated 100
times to estimate the variance in outcome variables. The study found that the
COVID-19 pandemic and associated lockdowns caused a significant increase in
breast cancer costs, with an average rise of 172.5 million PLN (95% CI [82.4,
262.6]) and an additional 1005 breast cancer deaths (95% CI [426, 1584]) in
Poland during the simulated period. While these results are preliminary, they
highlight the potential harmful impact of lockdowns on breast cancer treatment
outcomes and costs.
