CHICAGO — Screening by breast magnetic resonance imaging is warranted in women with a personal history of breast cancer, data from a retrospective study of 144 women suggest.
A review of 1,699 breast MRI studies performed at Memorial Sloan-Kettering Cancer Center in New York from 1999 to 2001 yielded 144 women with prior breast cancer who underwent breast MRI screening during that time and had more than 1 year of follow-up.
Biopsies were prompted by MRI screening in 44 women (31%), yielding malignancies in 17 (12%), Dr. Sandra B. Brennan reported at the annual meeting of the Radiological Society of North America. One patient had two metachronous cancers; thus 18 malignancies were found right away (17 cancers and 1 myxoid liposarcoma).
“In and of itself, a history of a prior breast cancer is a strong enough indication for screening MRI,” she said.
Of the 17 cancers, 12 (70.6%), were invasive (11 infiltrating ductal carcinoma and 1 invasive lobular carcinoma) and 5 cancers (29.4%) were ductal carcinoma in situ (DCIS). The median histologic size of invasive cancer was 0.8 cm (range, 0.2–4.3 cm).
Prior cancer histology had no significant impact on the cancer detection rate, said Dr. Brennan, a radiologist specializing in breast cancer imaging at Memorial Sloan-Kettering. Prior breast cancer histology was invasive in 126 patients (95 ductal, 26 lobular, 4 mixed lobular and ductal, and 1 unknown) and DCIS in 18 patients.
Of the 17 cancers detected by MRI, 10 were nonpalpable and detected by MRI only, and 7 had correlates on post-MRI mammography, ultrasound (2), or ultrasound, mammography, and physical examination (3).
The 10 cancers detected by MRI only were significantly more likely than the 7 cancers detected by other means to be DCIS (40% vs. 14%) or minimal breast cancer (70% vs. 43%), Dr. Brennan said. Minimal breast cancer was defined as DCIS or node-negative invasive breast cancer less than 1 cm in size.
More than two-thirds of cancers were detected during the first 2 years of screening (35% each in year 1 and in year 2), with two cancers (12%) detected in year 4 and one in each of years 5, 6, and 9.
The median MRI follow-up was 4 years (range, 1–9 years).
The investigators disclosed no conflicts of interest and received no funding for the study.