Cosmetic breast implants may not affect women’s long-term cancer risk, a new study shows.

The finding comes from a study of more than 3,400 Swedish women who had gotten cosmetic breast implants between 1965 and 1993. The women were about 32 years old, on average, when they had gotten their implants.

The women were followed from 30 days after getting breast implants until they died, moved away from Sweden, or through 2002, whichever came first. The average follow-up period was about 18 years.

During that time, the study’s participants had fewer than expected breast cancers when compared with the general Swedish female population. However, they had more than twice as many lung cancers as women in Sweden’s general public. No other cancers (including lymphoma, sarcoma, brain cancer, and multiple myeloma) stood out, the study shows.

The researchers included Joseph McLaughlin, PhD, of the International Epidemiology Institute in Rockville, Md.

Smoking and Lung Cancer

The study doesn’t show why any of the women with implants did -- or didn’t -- get cancer. It’s often hard for doctors to pinpoint cancer’s cause, since a variety of factors (including genetics, exposure to cancer-causing agents, and lifestyle) may affect cancer risk.

But McLaughlin and colleagues have some ideas about what the data may mean.

For instance, smoking was more common among the women with implants that they studied, compared with women in Sweden’s general public. Smoking has long been linked to lung cancer, though not all lung cancer patients are smokers and not all smokers have lung cancer.

An earlier study of a subgroup of the participants had shown that “women with implants were 2.8 times more likely to be current smokers than the general Swedish population," write McLaughlin and colleagues.

Breast Cancer Findings

The women with implants might have had certain traits that “may have put them at a lower risk of breast cancer,” the researchers write.

Those traits could include giving birth for the first time at younger ages, having more children, or having a lower BMI (body mass index). However, the study’s data didn’t show how many babies the women had, or at what age.

Possibly, women at higher risk for breast cancer are less likely to get implants, or perhaps preimplantation screening rules out women at higher risk for breast cancer, the researchers note.

Another explanation might be that breast cancers are detected later in women with implants. “But numerous studies have shown that women with implants are not diagnosed with more advanced stages of breast cancer or experience shorter survival than women without implants,” write McLaughlin and colleagues.

Researchers’ Conclusions

The researchers note that their findings are in line with other observational studies. Observational studies show patterns among groups of people, but they don’t prove a cause-and-effect relationship.

McLaughlin’s team sums up the findings this way: “After an average follow-up of 18 years and a maximum follow-up of 37 years, we found that women who have undergone breast implantation have a reduced risk for breast cancer, most likely due to differences in lifestyle or reproductive characteristics. We also found no increased risk for brain cancer or for lymphoma, sarcoma, or multiple myeloma.”

The types of breast implants that the women got aren’t noted in the study.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: McLaughlin, J. Journal of the National Cancer Institute, April 19, 2006; vol 98: pp 557-560. News release, Journal of the National Cancer Institute.