Search and Breast Cancer: On Episodic Shifts of Attention over Life Histories of an Illness

We seek to understand the evolving needs of people who are faced with a life-changing medical diagnosis based on analyses of queries extracted from an anonymized search query log. Focusing on breast cancer, we manually tag a set of Web searchers as showing patterns of search behavior consistent with someone grappling with the screening, diagnosis, and treatment of breast cancer. We build and apply probabilistic classifiers to detect these searchers from multiple sessions and to identify the timing of diagnosis using temporal and statistical features. We explore the changes in information-seeking over time before and after an inferred diagnosis of breast cancer by aligning multiple searchers by the estimated time of diagnosis. We employ the classifier to automatically identify 1700 candidate searchers with an estimated 90% precision, and we predict the day of diagnosis within 15 days with an 88% accuracy. We show that the geographic and demographic attributes of searchers identified with high probability are strongly correlated with ground truth of reported incidence rates. We then analyze the content of queries over time for inferred cancer patients, using a detailed ontology of cancer-related search terms. The analysis reveals the rich temporal structure of the evolving queries of people likely diagnosed with breast cancer. Finally, we focus on subtypes of illness based on inferred stages of cancer and show clinically relevant dynamics of information seeking based on the dominant stage expressed by searchers.