Cosmetic breast implants and breast cancer. / Kosmetiske brystimplantater og brystkreft.

BACKGROUND: The number of women with cosmetic breast implants has increased in recent decades in Norway. We compared the risk of detecting breast cancer and histopathological characteristics of the tumours in women with and without implants. MATERIAL AND METHOD: We retrieved information from the Cancer Registry's databases on implants and breast cancer among women who had participated in BreastScreen Norway in the period 1996-2016. Use of the data is pursuant to the Cancer Registry Regulations. We identified 785 706 women, of whom 10 086 (1.3 %) reported that they had an implant. We calculated the incidence rate ratio (IRR) with a 95 % confidence interval (95 % CI) for detected breast cancer and compared histopathological tumour characteristics among women with and without implants with the aid of descriptive analyses. RESULTS: The incidence rate ratio for breast cancer was 30 % lower for women with implants than for women without (IRR 0.70 (95 % CI 0.60-0.81)). Women with implants who had cancer detected had tumours with a larger diameter than women without, and several of these women had metastasis to axillary lymph nodes. INTERPRETATION: Women with implants who participated in BreastScreen Norway had a lower risk of detection of breast cancer, but more advanced disease upon diagnosis than those without implants. This may be due to the difficulty caused by implants in performing and interpreting the mammograms. The women should be informed about this before undergoing augmentation mammoplasty.