In a population of 10,000, beta carotene was given to 6000 people. The remainder did not receive any carotene. 3 out of the first group later suffered from lung cancer while 2 out of the secornd group (non-recepients) also got lung cancer. What is your reasonable conclusion?

The question reveals the following facts: Carotene intake Lung cancer present No lung cancer Total YES 3 5997 6000 NO 2 3998 4000 Disease among exposed: Out of 6000 people who were given beta carotene 3 developed lung cancer: 3/6000=1/2000 Out of 4000 people who did not receive 2 developed carcinoma: 2/4000 = 1/2000 This means that the same fraction of people developed lung cancer irrespective of whether they were or were not given beta carotene.No difference is found in incidence. Relative risk: Incidence of disease among exposed 1/2000 ------------------------------------------------ = ----------- = 1 Incidence of disease among non exposed 1/2000 Relative risk 1 denotes that there is no means of association Results thus clearly show that beta carotene and Lung cancer have no relation to each other. Ref:Park's Textbook of Preventive and Social Medicine By K. Park, 18th Edition, Pages 56, 72