Self-compression in mammography did not interfere with image quality and was associated with less discomfort in a 548-patient randomized trial, researchers reported.
Mean breast thickness with compression — the trial’s primary outcome measure — did not differ significantly between patients assigned to self-compression versus those undergoing the standard radiographer-performed kind, reported Philippe Henrot, MD, of Institut de Cancérologie de Lorraine Alexis Vautrin in France, and colleagues in JAMA Internal Medicine.
With a mean difference of 0.17 mm and a 95% confidence interval of −∞ to 1.89 mm, self-compression met the prespecified criterion for noninferiority, which was an upper limit to confidence interval of 3 mm.
For the four mammographic views, mean compression force was higher with self-compression than in the control group, which might suggest more discomfort. But self-reported pain scores were lower in the self-compression group (median score 2 vs 3 on a 10-point scale, P=0.009), and scores on the Mammography Questionnaire (addressing multiple components of patient satisfaction) did not differ significantly on any domain.
Henrot and colleagues noted that discomfort during conventional mammography is a factor in many women’s reluctance to undergo screening, although the researchers stopped short of calling self-compression a definitive solution. Instead, they concluded that it could be an option “for women who want to take an active role in their breast examination.”
As of now, there are no standards or guidelines to describe the optimal breast compression method, although compression is considered a key element in image quality. European guidelines suggest that compression should be both tolerable and firm, while the U.S. Mammography Quality Standards Act emphasizes that “compression shall be between 111 and 200 N,” the study authors highlighted.
A number of techniques have been suggested to limit compression pain or discomfort. The mechanical approach relies on devices that are designed to stop the compression at a certain threshold and assesses the ratio of force variation over thickness variation. However, this approach does not take into consideration the nonhomogeneity of the breast, and without evenly compressing the entire breast, the compression could primarily apply to the pectoral muscle in the mediolateral oblique view, Henrot and colleagues emphasized.
A new approach looks specifically at the ratio of compression force over contact area to analyze the pressure. Based on the individual breast plasticity and morphologic structure, this technique could provide uniformity with regard to the amount of compression, the investigators noted. “Improving the design of compression paddles (for example, using flexible devices) could also decrease discomfort. However, a preliminary study indicates that a flexible compression paddle could move breast tissue from the detector area at the chest wall side,” the researchers wrote.
Prior studies examined another option in which women control their breasts’ compression by having the radiographer compress one breast, while the woman compresses the other breast. Women were more likely to be satisfied with self-compression and didn’t experience as much pain; image quality did not decrease, Henrot and colleagues said.
By implementing the self-compression approach, the role of the radiographer does not change much, Henrot told MedPage Today. The radiographer is supposed to “to position the breast according to the guidelines, to explain, encourage and supervise self-compression, and, as for any mammogram, to check the quality of compression. Finally the radiologist has to check the image quality as for any mammogram and ask for any necessary additional views,” Henrot said
Patients in the current study were recruited from six French cancer centers and were randomized 1:1 to the different compression protocols. Participants’ mean age was 61.
Exclusion criteria included clinical breast abnormality, previous mastectomy, surgical procedures, and/or radiation therapy for breast cancer within the past 3 years, or history of breast operation for benign lesions and breast macrobiopsy using a 14-gauge or greater needle within the last year.
For the self-compression group, after standard positioning, the radiographer gave the patient control of the ongoing compression process after setting the compression to the amount of 40 N. For the standard compression group, the radiographer fully controlled compression and positioning.
For each arm, mammographic views were evaluated at left craniocaudal, right craniocaudal, left mediolateral oblique, and right mediolateral oblique. Subsequently, participants rated their pain level and completed a satisfaction questionnaire. Unaware of which technique was used, radiologists rated the quality of the four views based on motion artifacts. Radiologists could request extra views if they were unsatisfied with the image quality.
For the mean of left, right mediolateral oblique and left, right craniocaudal views, the reproducibility of breast thickness had an intraclass correlation coefficient of 0.917 (95% CI 0.902-0.929).
The investigators found no difference in the image quality scores of the two arms or in the number of extra views performed, regardless of the reason, including insufficient image quality (29 vs 27 insufficient quality views; P =0.65).
These findings are similar to those in previous investigations and confirm “that giving patients control over the degree of compression during mammography does not result in inferior quality and with a reduction of the self reported pain during the procedure,” Marc Inciardi, MD, of University of Kansas Health System in Kansas City.
“This paper adds to a limited, but growing body of research demonstrating that giving patients control over compression is generally beneficial. This appears to be the first multicenter study of this nature and includes a larger sample of patients,” he said.
Inciardi noted, though, that most of the study cohort had a “personal or family history of breast cancer and had undergone mammography previously, and therefore were more familiar with the procedure, and possibly more motivated to undergo the procedure, meaning that the results in this study may not be generalizable to women who have not had mammograms previously or have an average risk for breast cancer.”