To the Editor: In their cohort study, Dr Mørch and colleagues1 investigated the association between use of hormone therapy (HT) and ovarian cancer. It is important to consider the potential for detection bias in all such observational studies.
The most common presentation of asymptomatic ovarian cancer is the chance finding of a pelvic mass at manual or ultrasonic pelvic examination.2 Women using HT are likely to present for routine pelvic examination more often than nonusers of HT. The potential for such detection bias was not discussed in the article but could account for the small annual increase in ovarian cancer incidence of 1 in 8300.
MacLennan AH, Baber R. Hormone Therapy Use and Risk of Ovarian Cancer. JAMA. 2009;302(20):2203-2204. doi:10.1001/jama.2009.1724