After a person is diagnosed with cancer, increased surveillance among their family members may result in the earlier detection of asymptomatic familial cancers.
This phenomenon is called detection bias and may occur for a variety of cancers, according to a new study in the November 2 issue of the Journal of the National Cancer Institute.
Accurate assessments of the risk of cancer among the family members of cancer patients are essential for clinical and genetic counseling. Knowledge of these risks may also help to identify environmental and/or heritable factors that are associated with the risks of specific cancers and may lead to prevention strategies. Because a person's diagnosis of cancer may trigger the medical examination of their relatives and the subsequent identification of more cancers, detection bias may be present and the familial risks of cancer may therfore be overestimated.
Justo Lorenzo Bermejo, Ph.D., of the German Cancer Research Centre in Heidelberg, and Kari Hemminki, M.D., Ph.D., of the German Cancer Research Centre and the Karolinska Institute in Huddinge, Sweden, followed nearly 1.7 million offspring and siblings of almost 850,000 people who had been diagnosed with cancer. They compared the incidence of melanoma and cancers of the breast, cervix, colon/rectum, lung, and prostate among relatives of patients with the incidence of those cancers in the general population.