Study: MRI Does Little to Steer Breast Cancer Treatment

MRI shows little evidence of benefitting breast-cancer treatment, according to the first paper in The Lancet’s new series on breast cancer.

The findings show that although MRI is a valuable tool for screening women at genetically high risk of breast cancer, there is limited evidence to support its use in screening women in the general population, or that its routine use before breast-conserving surgery improves patient selection, reduces surgical procedures, or lowers the risk of local (confined to the breast) cancer recurrences.

MRI has, over recent years, been widely adopted into clinical practice based on the assumption that its increased sensitivity at detecting cancer will improve outcomes for patients. Surgical oncologist Monica Morrow, MD, of Memorial Sloan-Kettering Cancer Center and colleagues reviewed research from the past decade to examine that belief.

There is solid evidence that MRI is a beneficial screening tool in women at high risk of breast cancer (because of their family history or known gene mutation), and can accurately identify tumors missed by mammography and ultrasound. But little is known about whether or not this improved detection has an impact on survival.

Morrow and Colleagues found no evidence that increased sensitivity translates into better surgical treatment or prognosis when used to evaluate women prior to surgery.

The available data “do not support the idea that MRI improves patient selection for breast-conserving surgery or that it increases the likelihood of obtaining negative margins at the initial surgical excision,” they wrote, referring to cancer cells found in margins of resection.

The impact of MRI on longer-term outcomes such as the incidence of cancer in the other breast or the recurrence in the affected breast remains unclear because of a limited number of trials that are often low-quality anyway, the researchers said.

Research suggests that MRI is more reliable than traditional examinations such as physical examination, mammography, and ultrasonography at finding remnant cancer after preoperative chemotherapy. But whether that translates into an improved ability to select patients for breast-conserving therapy is unclear.

The real value of MRI might lie in its ability to predict biological behavior, rather than to quantitate low-volume disease, the researchers said.

“Very early changes in intracellular metabolism that are detectable by magnetic resonance spectroscopy seem to be predictive of response to treatment, and if validated in larger studies could avoid the toxicity and expense of continuing a chemotherapy regimen that will not be beneficial,” said the authors.