It usually takes many studies and years of research before definite conclusions can be drawn. Studies of groups of people who differ from your age, gender, health status, and ethnocultural background may not apply to you. In most cases, researchers need to study a large population over a long period of time to ensure that any observed differences are not simply the result of change. Sample size should be appropriate to the research question asked. Such a risk may sound much larger than it is.
Some clinical trials make the assumption that the number of years are equivalent.
Usually, if two studies show an agent is a cause of cancer in laboratory animals, the agent should be considered a potential cause of cancer in humans. If a researcher has received funding from an independent granting agency that uses a peer review process for evaluating and awarding research funds, the research findings will usually be more credible and less subject to bias than if the funding agency has a vested interest in the results. With partnerships among industry, university-based researchers and institutes, this can be a difficult issue to assess. Be open to explanations that do not fit existing beliefs or current knowledge because sometimes these are wrong or need modification. Review the research from more than one study and try to assess the possible risks and benefits to you making a change.