A clearly established link has been formed between a rare form of cancer and a certain type of breast implant, says France's National Cancer Institute.
The national cancer institute (INCa) said there had been 18 cases of the rare disease anaplastic large cell lymphoma since 2011, linked to silicone breast implants.
Given the rarity of the cases, the INCa said there was no need to recommend the removal of the implants. "This complication presents very infrequently," the body said.
France's health minister immediately sought to calm fears, with memories of faulty breast implants from the French firm PIP still fresh in the memory. "We do not recommend that women carrying these implants have them removed," Marisol Touraine told reporters.
She urged women not to be "carried away by excessive worry" about the implants. "Our vigilance is absolute," she said.
Touraine said no particular brand of implant was in question. However the Parisien daily reported that 14 of the 18 cases of the rare cancer were found in women with breast implants made by US pharmaceutical company Allergan.
Allergan said in a statement "the security of patients is our first priority," adding that the company was collaborating closely with the heath authorities and the drug agency ANSM. The company added that all women aged 25 or over should have an annual health check.
The head of the INCa, Agnes Buzyn, said the increased detection rate could also be attributed to better screening.
According to Francois Hebert, deputy head of the ANSM drugs agency, around 400,000 women carry breast implants in France - 80% for aesthetic reasons and 20% as a result of breast cancer.
French firm PIP sparked a global health scare in 2011, when plastic surgeons began reporting an unusual number of ruptures in their products. The PIP implants were banned and the company eventually liquidated.