They are extremely rare, he added, and the new warning should not cause any general concern. Realizing that ALCL was associated with breast implants had already “allowed us to be more aware that other things might be happening in this area,” said Dr. Clemens.

“If ALCL is uncommon, these are very rare,” he added. It has long been known that scar tissue, such as that formed after breast implant surgery, can lead to squamous cell carcinoma, added Dr. added Clement.

“A wound that’s trying to heal and trying to heal for a long time can develop into these things,” he said. But the exact nature of the relationship between the implant and the cancer, and whether the implant causes the cancer, is not yet clear, he said.

In a typical year, approximately 400,000 women in the United States receive breast implants, 300,000 for cosmetic reasons and 100,000 for reconstruction after mastectomies performed to treat or prevent breast cancer.

Numbers dropped significantly in the first year of the pandemic, according to the American Society of Plastic Surgeons.

Last year, the FDA put so-called black-box labels on breast implants, warning that they have been linked to a variety of chronic conditions, including autoimmune diseases, joint pain, mental confusion, muscle pain and chronic fatigue to lymphoma.