What are the trigger events that lead to detection of otherwise asymptomatic thyroid cancers?
Background: The incidence of thyroid cancer has more than doubled in the past 30 years, but mortality has remained stable. Cancers never destined to cause symptoms during the person’s life are being detected and treated, leading to unnecessary surgery with potentially long-term consequences.
Study design: Retrospective cohort
Setting: VA Outcomes Group, Department of Veterans Affairs Medical Center, White River Junction, Vermont; Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, New Hampshire; University of Vermont College of Medicine, Burlington
Synopsis: Of 279 thyroidectomies performed, 95 new diagnoses of thyroid cancer were made. Just less than half (46 percent) of identified cancers were among the 127 thyroidectomies performed after identification of a thyroid abnormality by either screening or chance. Physician screening examination was the trigger event for 49 thyroidectomies (18 percent). The authors said “serendipity” was the trigger event for 41 thyroidectomies (15 percent). Diagnostic cascade was the trigger event for 33 thyroidectomies (12 percent); and 75 thyroidectomies (27 percent) were performed because of symptoms directly referable to a neck mass. According to the authors, some proportion (possibly all) of the 46 percent of cancers found by physician screening or chance represent detection of the subclinical reservoir of disease. The study’s major limitation was the potential for case misclassification.
Background: Close to half of the thyroid cancers diagnosed at two institutions by physician screening and chance were presumably asymptomatic subclinical cancers and may not have warranted surgery.
Citation: Davies L, Quellette M, Hunter M, et al. The increasing incidence of small thyroid cancers: where are the cases coming from? Laryngoscope. 2010;120(12): 2446-2451.
—Reviewed by Sue Pondrom