Breast tumors in woman with implants are usually detected at smaller sizes compared to women without them, according to a new study. But screening via mammography seemed to be less effective in these women, detecting fewer tumors than in those without implants.

The study, “Breast Cancer following Augmentation Mammaplasty: A Case-Control Study,” was published in the journal Plastic and Reconstructive Surgery, the official journal of the American Society of Plastic Surgeons.

Researchers analyzed 48 cases of breast cancer patients who had undergone breast augmentation. On average, 14 years elapsed between their breast procedure and a diagnosis of cancer. Patients underwent treatment from 2000 to 2013.

Women with breast cancer who did not have breast implants, a total of 302, were used as controls. Researchers compared both groups to assess whether breast augmentation and the presence of implants affected breast cancer detection, stage, and treatment.

At diagnosis, breast tumors were significantly smaller in women with breast implants compared to controls — on average, 1.4 cm compared to 1.9 cm. Palpable masses, detected during a breast self-exam or clinical exam, were also smaller in women with breast implants (1.6 cm) compared to controls (2.3 cm).

So while women with breast implants seemed to have smaller tumors, their rate of detection using standard mammograms was lower compared to that of women without implants — 77.8% vs. 90.7%.

Diagnosis via excisional biopsy — the surgical removal of a tumor and some surrounding normal tissue — was more common in women with implants: 20.5% vs. 4.4%. Those without implants were more likely to undergo image-guided core needle biopsy, where only a small sample is removed for further analysis.

Researchers also detected differences related to treatment options. Women with implants underwent mastectomy (the removal of one or both breasts) more often than controls — 73% vs. 57%.

They were also less likely to undergo breast-conserving treatment — 27% vs. 43% — although researchers said this is still an option for these patients.

Neither the type of implant (saline vs. silicone-filled) or its anatomic location (over or under the pectoral muscle (the muscle situated at the chest) affected breast cancer detection.

But a trend suggested that mammography exams were more likely to detect tumors in women with saline-filled implants.

These findings show that while breast tumors are generally detected at smaller sizes in women with implants, modern mammography techniques are more prone to fail in these women.

“Our findings may have important implications for patient counseling regarding breast augmentation and breast cancer detection,” Michael Sosin, MD at the MedStar Georgetown University Hospital, Washington, D.C., and the study’s first author, said in a press release.