Cosmetic breast implants do not increase the overall risk of getting cancer, a long-term study suggests.
Cosmetic breast implants are increasingly popular
US researchers found women with implants had a lower breast cancer risk but a higher chance of lung cancer.
However, in both instances this could be due to factors such as having children and smoking rather than any effect of the implants, they say.
The Journal of the National Cancer Institute study followed 3,486 Swedish women for an average of 18.4 years.
The researchers, from the International Epidemiology Institute in Maryland, and the Vanderbilt-Ingram Cancer Center in Nashville, believe their study is the longest follow-up of women with breast implants to date.
The International Agency for Research on Cancer has concluded that silicone implants are not cancer-causing.
The conclusion has been echoed by several other scientific review bodies.
However, the researchers say they were keen to do a definitive long-term study as some research, and anecdotal reports, have raised doubts.
Breast augmentation surgery is becoming increasingly popular.
In the UK last year 5,655 operations were carried out by members of the British Association of Aesthetic Plastic Surgeons - up 51.4% on 2004.
Overall, the researchers identified 180 cancers in women with breast implants, compared with the 193 cases they would have expected to find in a similar sample from the general population.
Twenty women developed lung cancer, compared with the projected figure of nine.
But just 53 women developed breast cancer - 19 cases fewer than expected.
The researchers said women who underwent breast implant surgery tended to be slimmer, to have more children, and to have children earlier in life - all factors associated with a decreased risk of breast cancer.
The raised risk of lung cancer could be down to differences in smoking rates, they said.
The study also found no evidence that breast implants increase the risk of other types of cancer, such as brain cancer, lymphoma, sarcoma, or multiple myeloma.
Hazel Nunn, science information officer at Cancer Research UK, said: "There are many reasons why women may choose to have breast implants and this new study is reassuring for all women who have had them.
"However we do know that breast implants can interfere with regular breast screening, so it is important that women with breast implants tell their radiographer that they have implants to ensure the best possible x-ray is taken."
Douglas McGeorge, president of the Association of Aesthetic Plastic Surgeons, said: "There are no known health risks associated with breast augmentation."