Cancer recurrence times from a branching process model

As cancer advances, cells often spread from the primary tumor to other parts of the body and form metastases. This is the main cause of cancer related mortality. Here we investigate a conceptually simple model of metastasis formation where metastatic lesions are initiated at a rate which depends on the size of the primary tumor. The evolution of each metastasis is described as an independent branching process. We assume that the primary tumor is resected at a given size and study the earliest time at which any metastasis reaches a minimal detectable size. The parameters of our model are estimated independently for breast, colorectal, headneck, lung and prostate cancers. We use these estimates to compare predictions from our model with values reported in clinical literature. For some cancer types, we find a remarkably wide range of resection sizes such that metastases are very likely to be present, but none of them are detectable. Our model predicts that only very early resections can prevent recurrence, and that small delays in the time of surgery can significantly increase the recurrence probability.Comment: 26 pages, 9 figures, 4 table

Epidemiology of Eosinophilic Esophagitis

Great strides have been made in understanding the epidemiology of EoE over the past two decades. Initial research focused on case description and characterization of the burden of disease. Research is now shifting to risk factor ascertainment, resulting in new and intriguing etiologic hypotheses. This paper will review the current knowledge related to the epidemiology of EoE. Demographic features and natural history will be described, data summarizing the prevalence and incidence of EoE throughout the world will be highlighted, and risk factors for EoE will be discussed. EoE can occur at any age, there is a male predominance, it is more common in Whites, and there is a strong association with atopic diseases. EoE is chronic, relapses are frequent, and persistent inflammation increases the risk of fibrostenotic complications. The prevalence is currently estimated at 0.5–1 in 1000, and EoE is now the most common cause of food impaction. EoE can be seen in 2–7% of patients undergoing endoscopy for any reason, and 12–23% undergoing endoscopy for dysphagia. The incidence of EoE is approximately 1/10,000 new cases per year, and the rise in incidence is outpacing increases in recognition and endoscopy volume. The reasons for this evolving epidemiology are not yet fully delineated, but possibilities include changes in food allergens, increasing aeroallergens and other environmental factors, the decrease of H. pyloriand early life exposures