The authors emphasise that because anaplastic large T-cell lymphoma (ALCL) of the breast is so rare, the absolute risk is still very low.
Dr Daphne de Jong, from The Netherlands Cancer Institute, Amsterdam, and colleagues evaluated the association between silicone implants and this cancer after identifying two patients who had ALCL in the fibrous capsule surrounding their silicone breast implants. Although similar cases had been reported in the literature, no formal studies have examined the topic.
A search of a Dutch pathology database identified 11 women (average age of 40 years) who were diagnosed with ALCL of the breast from 1990 to 2006. Each patient was matched by age and year of diagnosis to one or more women with other types of lymphomas in the breast (the control group).
Five of the ALCL patients had received silicone implants in both breasts 1 to 23 years prior to diagnosis, the authors report in the Journal of the American Medical Association. In all five women, the implants were placed for cosmetic reasons.
The most common lymphoma in the control group was diffuse large B-cell lymphoma, followed by mucosa-associated lymphoid tissue-type lymphoma. Just 1 of the 35 control patients had a breast implant prior to their lymphoma diagnosis.
"The odds ratio for ALCL in the breast associated with silicone breast prosthesis placed for cosmetic reasons was 18.2," the investigators calculate.
As noted, though, the absolute risk of ALCL with silicone breast implants is exceedingly small. The authors calculate that just 0.1 to 0.3 cases per 100 000 women with implants would arise per year.
"These findings must be considered preliminary and hypothesis-generating and are not strong enough to definitively conclude that breast implants predispose women to non-Hodgkin lymphoma," Dr Andrew M. Evens and Dr Brian C.-H. Chiu, from Northwestern University, Chicago, write in an accompanying editorial.
"However," they add, "given that silicone is immunogenic, further evaluation of breast implant-related lymphoma is warranted, particularly by studies with statistical power, sufficient follow-up, and information on other factors." - (Reuters Health)