Risk of Breast Implant–Associated Anaplastic Large Cell Lymphoma—Reply

In Reply We appreciate the comments on our article. Although relative cancer risk estimates are important for the understanding of oncogenetic processes, it is the excess absolute risk that should be the basis for health care decisions for patients and clinicians alike. Robust epidemiological studies to reliably determine the risk for breast implant–associated anaplastic large cell lymphoma (BIA-ALCL) are required to place the high relative risk in perspective. These studies fully depend on unbiased identification of BIA-ALCL and reference disease cases as can be retrieved from population-based, preferably national, comprehensive disease registries and on valid assessment of exposure. In the Netherlands, all these preconditions are available, permitting reliable epidemiological studies on the long-term effects of certain medical exposures on rare diseases, including breast-ALCL in women with breast implants. Various other published studies on risk assessment in BIA-ALCL are limited by bias from case registrations in nonmandatory (national) registries and international collaborative efforts based on poorly defined populations, dual entries in registries, and lack of central pathology review. Because implant registries have only been operational in the past few years and in few countries, reliable estimates of implant carrier prevalence, as well as the use of specific implant types over the past years, is largely lacking. These limitations lead to unpredictable overestimation and underestimation of absolute risks. Also, observed associations of BIA-ALCL with certain implant types should be approached with caution because not only is the use of textured vs smooth implants variable around the world and over time, also implant history in individual patients is often unknown. Considering that the interval between BIA-ALCL diagnosis and time of first implant is more than 10 years (mean, 13 years; range, 1-39 years) these aspects preclude strong statements and the issue should be considered unsettled for now.

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