TUESDAY, April 19 (HealthDay News) -- New research suggests a link between breast implants and a rare form of lymphoma, but it's not known if the implants actually cause the cancer or how the disease might develop.

The researchers, from the nonprofit RAND Corporation, also found that this type of lymphoma (a type of immune system cancer) progresses slowly and can be treated by surgical removal of the breast implant and surrounding capsule. The findings are published in the April 15 online edition of the journal Plastic and Reconstructive Surgery.

Concerns about a possible link between breast implants and anaplastic large cell lymphoma (ALCL) were first raised in 1996 with the publication of a report by doctors who described the case of a woman with implants who developed ALCL in tissue next to one of her implants.

Since then, similar published reports have estimated that between one case and three cases of ALCL would be diagnosed each year for every one million women with breast implants.

For this study, the RAND researchers reviewed the medical literature about breast implants and ALCL and also convened a panel of experts to evaluate the evidence for a possible link between the two.

"Much more research is still needed to explore the link between breast implants and ALCL and the clinical significance of this rare disease, but our findings provide useful information for both patients and physicians in the near term," senior author Dr. Soeren Mattke, a senior scientist at RAND, said in a corporation news release.

In their review, Mattke and colleagues identified 36 published cases of non-Hodgkin lymphoma among women with breast implants; of those, 29 were diagnosed with ALCL. The researchers found no evidence that disease risk was influenced by patient risk factors or particular types of implants.

Some of the women received chemotherapy and/or radiation, but most had surgery to remove the affected implant and surrounding tissue. There were no deaths among the 16 patients for whom follow-up information was available, the researchers said.

The review findings were presented to the expert panel, who concluded that the evidence suggests an association between breast implants and ALCL, but does not definitively prove that implants cause the cancer or explain how implants might trigger it.

The panelists also recommended that the appearance of a fluid-filled sac near a breast implant at least six months after surgery calls for a diagnostic evaluation for ALCL.

The U.S. Food and Drug Administration and the American Society of Plastic Surgeons announced recently a plan to create a registry to collect data on women with breast implants who have been diagnosed with ALCL.

The study was commissioned by the Plastic Surgery Foundation and the Aesthetic Surgery Education and Research Foundation.

More information

The Lymphoma Research Foundation has more about ALCL.