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Writing the Abstract
Activity 1 Stating an Abstract’s Conclusions and Implications
When writing your abstract, you must include everything your reader will need to know to understand how you arrived at your conclusions. By the time an author has written the rest of the paper and is writing the abstract, the information may seem so familiar that he or she neglects to mention a vital fact that is necessary for the reader to understand the study or its conclusions. Therefore, when writing the abstract, always ask, “Does the information I’ve included about the background, methods, and results support my conclusion?” If the answer is no, the logic of your abstract will be flawed. The following structured abstract contains all the information needed to draw a specific conclusion. Read the entire abstract and write a conclusion that is supported by the facts given. Then write a sentence suggesting a possible implication of the study’s conclusion. Background: After the Chernobyl nuclear power plant accident in April 1986, a large increase in the incidence of childhood thyroid cancer was reported in contaminated areas. Most of the radiation exposure to the thyroid was from iodine isotopes, especially 131 I. There is compelling evidence that the observed increase in childhood thyroid cancer is related to the fallout from Chernobyl, but questions remain concerning the magnitude of the thyroid cancer risk associated with these radiation exposures and the role of iodine deficiency in modifying this risk. We carried out a population-based case-control study of thyroid cancer in Belarus and the Russian Federation to evaluate the risk of thyroid cancer after exposure to radioactive iodine in childhood and to investigate environmental and host factors that may modify this risk. Methods: We studied 276 case patients with thyroid cancer through 1998 and 1300 matched control subjects, all aged younger than 15 years at the time of the accident. Individual radiation doses were estimated for each subject based on his or her whereabouts and dietary habits at the time of the accident and in the following days, weeks, and years; subjects’ likely stable iodine status at the time of the accident was also evaluated. Data were analyzed by conditional logistic regression using several different models. All statistical tests were two-sided. Results: A strong dose-response relationship was observed between radiation dose to the thyroid received in childhood and thyroid cancer risk ( P < 0.001). For a dose of 1 Gy, the estimated odds ratio of thyroid cancer varied from 5.5 (95% confidence interval [CI] = 3.1 to 9.5) to 8.4 (95% CI = 4.1 to 17.3), depending on the risk model. A linear dose-response relationship was observed up to 1.5 to 2 Gy. The risk of radiation-related thyroid cancer was three times higher in iodine-deficient areas (relative risk [RR]= 3.2, 95% CI = 1.9 to 5.5) than elsewhere. Administration of potassium iodide as a dietary supplement reduced the risk of radiation- related thyroid cancer by a factor of 3 (RR = 0.34, 95% CI = 0.1 to 0.9, for consumption of potassium iodide versus no consumption). Conclusions: [Our results show that ....] [These findings suggest that ....]
Adapted from Cardis E et al. Risk of thyroid cancer after exposure to 131 I in childhood. J Natl Cancer Inst 97:724–732, 2005.
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