Abstract P4-02-02: Did adding breast MRI decrease the surgical margin involved rate than conventional breast image? - A case controlled comparison analysis
Authors: Lai H-W , Chen S-T , Chen D-R , Wu H-K , Ku S-J 
Published: May 2016

Purpose: Resection of primary tumor with clear margin is the goal of surgical management for primary operable breast cancer. Surgical margin involvement was associated with increased local recurrence, and usually mandated further surgery. The objective of current study is to assess whether combining breast MRI would decrease the rate of margin involvement compared with conventional breast image.

Material and Methods: A retrospective, case controlled comparison study was conducted. Patients with primary operable breast cancer who received surgical management were searched from Changhua Christian Hospital (CCH) breast cancer database. The rate of surgical margin involvement was compared between two groups of patients with conventional breast image (Group A: mammogram and sonogram) or combined with breast MRI (Group B: mammogram, sonogram and MRI). Surgical margin involvement was defined as cancer cells present at surgical margin, or &lt; 1mm. To further evaluate the effect of breast MRI on surgeon's margin involved rates, the index surgeons, defined as with more than 100 breast cancer operations in both Group A and Group B, were selected and analyzed.

Results: Group A, conventional breast image group, consisted of 741 breast cancer patients. Among them, 381(51.4%) received partial mastectomy, and 360 (48.6%) received total mastectomy. Overall, 66 (8.9%) margin involved events were found in Group A. The margin involved rate in Group A patients received partial mastectomy or total mastectomy was 14.4% (55/381), and 3.1% (11/360), separately. The Group –B (combined with MRI) consisted of 736 breast cancer patients. Among them, 347 (47.1%) received partial mastectomy, and 389(52.9%) received total mastectomy. The margin involved rate in Group B was overall 4.8%(35/736). The margin involved rate in Group B patients who received partial mastectomy or total mastectomy was 6.1%(21/347), and 3.6% (14/ 389), respectively. The surgical margin involved rate was decreased after combination of MRI to conventional breast image as showed in table 1.

Margin involved rate with conventional breast image or combined with MRI Conventional Breast ImageCombined Breast MRI Patient741736P valuePartial mastectomy51.4%47.1%0.107Total mastectomy48.6%52.9% Rate of margin involvement  P valueOverall8.9%4.8%0.002Partial mastectomy14.4%6.1%0.001Total mastectomy3.1%3.6%0.834

Two index surgeons were selected for comparison of surgical margin involved rate before and after breast MRI. The "Surgeon A" 's margin involved rate in conventional breast image -&gt; combined MRI were: overall: 7.6% -&gt; 4.9%(0.202), partial mastectomy: 14.0% -&gt; 8.1%(P=0.151), and total mastectomy: 1.3% -&gt; 2.2%(P=0.8066). "Surgeon B" ‘s margin involved rate (from no MRI -&gt; MRI ) was: overall: 9.0% -&gt; 5.0%(P=0.121), partial mastectomy: 12.1% -&gt; 3.9%(P=0.034), and total mastectomy: 6.2% -&gt; 6.59%(P=0.722).

Conclusion: Adding breast MRI to conventional breast image decreased the surgical margin involved rate, with the cost of mild increase the mastectomy rate. This decreasing surgical margin involved rate was not mainly due to increase mastectomy rate, but due to the selection of patients who were not suitable for partial mastectomy to receive total mastectomy.

Citation Format: Lai H-W, Chen S-T, Chen D-R, Wu H-K, Ku S-J. Did adding breast MRI decrease the surgical margin involved rate than conventional breast image? - A case controlled comparison analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-02-02.