A rare type of cancer linked to breast implants is much more common than previously thought, Australian health authorities say.
The country's Therapeutic Goods Administration (TGA) said as many as one in 1000 Australian women who got breast implants would develop Anaplastic Large Cell Lymphoma (ALCL).
Health authorities and surgeons had believed the risk was somewhere between one in three million and one in 50,000.
The TGA now estimated the risk ranged between one in 10,000 and one in 1000.
Forty-six cases have been diagnosed in Australia and New Zealand.
But health authorities do not recommend removing implants as a preventative measure.
Instead, women should monitor their breasts for any changes and consult their surgeon if they have concerns.
Breast implant-associated ALCL is not breast cancer and is highly treatable with most cases, cured by removal of the implant and the capsule surrounding the implant.
The cancer is linked to bacteria-contaminated breast implants.
Associate professor Anand Deva, head of the discipline of plastic and reconstructive surgery at Macquarie University's MQ Health, said if surgery was performed without proper infection controls, bacteria could enter the body, and slowly cause scar tissue to harden around the implants.
Over several years, the infection placed stress on the patient's lymphatic system and in some cases triggered ALCL.
Textured implants, which were popular in Australia, were 70 times more likely to be contaminated because they were difficult to keep sterile during surgery, Dr Deva said.
"We now know macro-textured implants, which have a higher surface area, carry a significantly higher risk of BIA-ALCL," he said.
However, surgeons have urged women with breast implants not to panic.
Australian Society of Plastic Surgeons president Dr James Savundra said women should get their implants checked regularly.
"It's important to emphasise that the risk still remains very low, so unless there are associated symptoms such as a sudden swelling of the breast or a lump, women do not need to have implants removed," he said.
Australasian College of Cosmetic Surgery spokesperson Daniel Fleming said the vast majority of women with breast implants would not get ALCL.
"The risk is still more than 100 times less likely than the risk of any Australian woman of developing breast cancer in her lifetime, which is about one in eight," he said.
Dr Fleming said most women with ALCL made a full recovery after surgery.
"Most patients do not have invasive cancer and it can be cured by the removal of the implants and the membrane surrounding the implants," he said.