Question

6.
In
In a certain population, on an average, 13 new
cases of esophageal cancer are diagnosed each
year. If the annual incidence of esophageal
cancer follows Poisson distribution, find the
probability that in given year the number of
newly diagnosed cases will be (i) exactly 10
(ii) at least 2 (iii) not more than 4.
[Use e-" = 0.0000022]​

Answer 1

Answer:

Esophageal cancer is one of the most unknown and deadliest cancers worldwide, mainly because of its extremely aggressive nature and poor survival rate. Esophageal cancer is the 6th leading cause of death from cancer and the 8th most common cancer in the world. The 5-year survival is around 15%-25%. There are clear differences between the risk factors of both histological types that affect their incidence and distribution worldwide. There are areas of high incidence of squamous cell carcinoma (some areas in China) that meet the requirements for cost-effectiveness of endoscopy for early diagnosis in the general population of those areas. In Europe and United States the predominant histologic subtype is adenocarcinoma. The role of early diagnosis of adenocarcinoma in Barrett’s esophagus remains controversial. The differences in the therapeutic management of early esophageal carcinoma (high-grade dysplasia, T1a, T1b, N0) between different parts of the world may be explained by the number of cancers diagnosed at an early stage. In areas where the incidence is high (China and Japan among others) early diagnoses is more frequent and has led to the development of endoscopic techniques for definitive treatment that achieve very effective results with a minimum number of complications and preserving the functionality of the esophagus.

Keywords: Oesophageal cancer, Adenocarcinoma, Squamous cell carcinoma, Epidemiology, Barrett’s oesophagus, Screening, Early stage, Endoscopic mucosal resection, Endoscopic submucosal disection

Step-by-step explanation:

Core tip: Esophageal cancer is a disease with a non-negligible impact, being the 6th leading cause of death from cancer, and with a very high morbidity and mortality due to diagnosed in advanced stages. A better understanding of the epidemiology, the natural history, and the risk factors could lead to an earlier diagnosis and treatment by endoscopic methods or by other less aggressive techniques. As a result, we could improve treatment outcomes, even though less aggressive modalities. This article provides a global perspective by comparing the management of esophageal cancer in Western and Eastern countries with particular emphasis on current prevention strategies.

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EPIDEMIOLOGY OF ESOPHAGEAL CANCER

Esophageal cancer is the 6th leading cause of death from cancer and the 8th most common cancer in the world. The 5-year survival is around 15%-25% and the best results are related to early diagnosis, which is commonly known as "early stages"[1].

Esophageal squamous cell carcinoma is the predominant histological type worldwide. However, at present, in countries like United States, Australia, United Kingdom and Western Europe (Finland, France, Norway), there is a preponderance of adenocarcinoma subtype, having squamous carcinoma moved to second place[1]. The so-called “Asian Esophageal Cancer Belt” encompasses areas such as Turkey, Iran, Kazakhstan and northern and central China, with an estimated esophageal squamous carcinoma of more than 100 cases/100000 person-years. Another area with high incidence of squamous cell carcinoma is southeastern Africa, with similar rates to those observed in Eastern countries. In the United States, from 1975-2004, the age-adjusted incidence in white males has increased from 5.76 to 8.34 cases/100000 person-years at the expense of the adenocarcinoma histological subtype. Nevertheless squamous carcinoma remains the most common subtype in American black males, but still adenocarcinoma, is one of the few cancers that contributes to an increased mortality from cancer among American men[2]. The trend towards dominance of adenocarcinoma subtype is not limited only to North America. In European countries like the United Kingdom, France or Norway the age-adjusted incidence increased by 39.6% for men and 37.5% for women in the last five years[1]. There is also a significant difference between gender distributions; the incidence of this disease is about 2-4 fold higher among males compared to females[3]. The incidence rates of squamous neoplasia in men in the territory of “Asian Esophageal Cancer Belt” are around 23 cases/100000 person-years and 16 cases/100000 person-years for females. In South Africa similar rates for males have been estimated[4]. Mortality rates follow, overall, a major parallelism with incidence rates in each country[5] (Figure ​(Figure1).1). Regarding race, age-adjusted mortality for black individuals have a tendency to decrease, but still it is two-fold higher compared to Caucasians (7.79 vs 3.96, P < 0.05)[2].