Efficacy of radiation boost after breast-conserving surgery for breast cancer with focally positive, tumor-exposed margins

Impact of radiation therapy for breast cancer with involved surgical margin after immediate breast reconstruction: A multi-institutional observational study

INTRODUCTION

Involved surgical margins are risk factors for local recurrence and re-excision is often difficult, particularly in patients with breast cancer undergoing immediate breast reconstruction (IBR). However, the magnitude of the effect of radiation therapy on preventing local recurrence for breast cancers with involved margins has not been sufficiently assessed.

MATERIALS AND METHODS

We retrospectively assessed sites of involved surgical margins and local recurrence after mastectomy with IBR in patients with early breast cancer between 2008 and 2016. The effect of postoperative radiation therapy was evaluated in patients with involved margins, adjusted for nuclear grade, lymphatic invasion, surgical procedures, and primary systemic therapy.

RESULTS

A total of 274 (5.8 %) out of 4726 patients who underwent mastectomy with IBR had involved surgical margins: 133, 68, 88, and 26 had involvement of the skin, deep margin, lateral margins, and nipple, respectively (including duplicates). Radiation therapy was administered to 54 patients with involved margins. In patients with involved margins, 7-year cumulative incidences of local recurrence were 1.9 % and 12.6 % with and without radiation therapy, respectively (adjusted hazard ratio, 0.17; 95 % CI, 0.04-0.80). Local recurrence occurred in 28 patients, and the sites were skin, subcutaneous tissue, muscle, and nipple-areola complex in 7, 17, 1, and 3 patients, respectively. Among them, 23 (82.1 %) were associated with involved margin sites.

CONCLUSIONS

Radiation therapy meaningfully reduced the incidence of local recurrence in patients with breast cancer with margin involvement after mastectomy with IBR. Most local recurrences occurred at involved margin-related sites.

Tailored radiation dose according to margin width for patients with ductal carcinoma in situ after breast-conserving surgery

A 2 mm resection margin is considered adequate for ductal carcinoma in situ (DCIS). We assessed the effectiveness of a tailored radiation dose for margins < 2 mm and the appropriate margin width for high-risk DCIS. We retrospectively evaluated 137 patients who received adjuvant radiotherapy after breast-conserving surgery for DCIS between 2013 and 2019. The patients were divided into three- positive, close (< 2 mm), and negative (≥ 2 mm) margin groups. Radiation dose to the tumor bed in equivalent dose in 2 Gy fractions were a median of 66.25 Gy, 61.81 Gy, and 59.75 Gy for positive, close, and negative margin groups, respectively. During a median follow-up of 58 months, the crude rates of local recurrence were 15.0%, 6.7%, and 4.6% in the positive, close, and negative margin groups, respectively. The positive margin group had a significantly lower 5-year local recurrence-free survival (LRFS) rate compared to the close and negative margin groups in propensity-weighted log-rank analysis (84.82%, 93.27%, and 93.20%, respectively; p = 0.008). The difference in 5-year LRFS between patients with the high- and non-high-grade tumors decreased as the margin width increased (80.4% vs. 100.0% for margin ≥ 2 mm, p < 0.001; 92.3% vs. 100.0% for margin ≥ 6 mm, p = 0.123). With the radiation dose tailored for margin widths, positive margins were associated with poorer local control than negative margins, whereas close margins were not. Widely clear margins (≥ 2 mm) were related to favorable local control for high-grade DCIS.

Implementation of a Breast Intraoperative Oncoplastic Form to Aid Management of Oncoplastic Surgery

INTRODUCTION

Oncoplastic breast conservation surgery (BCS) uses concurrent reduction and/or mastopexy with lumpectomy to improve aesthetic outcomes. However, tissue rearrangement can shift the original tumor location site in relation to external breast landmarks, resulting in difficulties during re-excision for a positive margin and accurate radiation targeting. We developed the Breast Intraoperative Oncoplastic (BIO) form to help depict the location of the tumor and breast reduction specimen. This study seeks to assess physician perspectives of the implementation outcomes.

METHODS

From February 2021 to April 2021, the BIO form was used in 11 oncoplastic BCS cases at a single institution. With institutional review board approval, surgical oncologists (SOs), plastic surgeons (PSs), and radiation oncologists (ROs) were administered a 12-question validated survey on Acceptability of Intervention Measure (AIM), Intervention Appropriateness Measure (IAM), and Feasibility of Intervention Measure (FIM), using a 5-point Likert scale during initial implementation and at 6-month reassessment.

RESULTS

Twelve physicians completed the survey initially (4 SOs, 4 PSs, and 4 ROs). The mean scores for Acceptability of Intervention Measure, Intervention Appropriateness Measure, and Feasibility of Intervention Measure were high (4.44, 4.56, and 4.56, respectively). Twelve completed the second survey (5 SOs, 3 PSs, and 4 ROs). The mean scores were marginally lower (4.06, 4.21, and 4.25). There were no significant differences when stratified by number of years in practice or specialty. Free text comments showed that 75% of physicians found the form helpful in oncoplastic BCS.

CONCLUSIONS

The data indicate high feasibility, acceptability, and appropriateness of the BIO form. Results of this study suggest multidisciplinary benefits of implementing the BIO form in oncoplastic BCS.

Effect of high-dose radiation therapy on positive margins after breast-conserving surgery for invasive breast cancer

PURPOSE

Positive margins after breast-conserving surgery are associated with poor oncological outcomes and warrant additional surgery. This study aimed to evaluate the effectiveness of high-dose radiation therapy for positive margins by comparing local recurrence between patients with positive and negative margins.

METHODS

We retrospectively evaluated 550 patients treated with adjuvant radiation therapy after breast-conserving surgery for invasive breast cancer between 2013 and 2019. The total equivalent dose in 2 Gy fractions (EQD2) to the tumor bed ranged from 65.81 to 66.25 Gy for positive margins and 59.31-61.81 Gy for negative margins. The differences in local recurrence between the positive and negative margin groups were analyzed.

RESULTS

After a median follow-up of 58 months, the crude local recurrence rate was 7.3% in the positive margin group (n = 55) and 2.4% in the negative margin group (n = 495). Positive margins were associated with higher local recurrence without statistical significance in the entire cohort (p = 0.062). Among patients aged <60 years, those with positive margins had a significantly lower 5-year local recurrence-free survival rate than those with negative margins (89.16% vs. 97.57%, respectively; p = 0.005). In contrast, there was no significant difference in the 5-year local recurrence-free survival rate between patients with positive and negative margins among those aged ≥60 years (100.00% vs. 94.38%, respectively; p = 0.426).

CONCLUSION

In this study, positive margins were not associated with poor local control in older patients after a high-dose boosts. Further prospective studies are needed to verify our findings.

Dosimetric comparison between three-dimensional conformal radiotherapy followed by electron beam boost and volumetric modulated arc therapy using concomitant boost for the heart and cardiac segments in patients with left-sided breast cancer at risk for radiation-induced cardiac toxicity

PURPOSE

We aimed to compare dosimetric parameters between three-dimensional conformal radiation therapy followed by electron beam boost (3D-CRT + EB) and volumetric modulated arc therapy using simultaneous integrated boost (SIB-VMAT) in left-sided breast cancer patients.

METHODS

This study included 57 patients with left-sided breast cancer who underwent SIB-VMAT. All patients had a computed tomography-based maximum heart distance of ≥ 1 cm and were prescribed a dose of 42.56 Gy/16 fractions to the planning target volume and a concomitant-boosted target dose of 53.2 Gy or 51.2 Gy. The 3D-CRT + EB plan was retrospectively created for the purpose of comparison using tangential fields with field-in-field technique followed by electron beam irradiation.

RESULTS

The doses to the clinical target volume significantly improved in the SIB-VMAT plans. All dosimetric parameters for the left anterior descending coronary artery (LAD) and LAD middle position (LAD mid) in the SIB-VMAT plans were significantly lower than those for 3D-CRT + EB plans (P < 0.01), while the doses to the heart, lung, contralateral breast and non-target tissue were decreased in the 3D-CRT + EB plans compared with those in the SIB-VMAT plans (e.g., 1.9 Gy vs. 2.9 Gy; P < 0.001 for the mean dose of heart).

CONCLUSIONS

SIB-VMAT significantly improved the dose to the target while reducing the doses to the LAD and LAD mid, whereas 3D-CRT + EB significantly decreased the doses to the heart and other organs at risk in patients with left-sided breast cancer at risk for radiation-induced coronary artery disease.

A comparative study of perioperative techniques to attain negative margins and spare healthy breast tissue in breast conserving surgery

BACKGROUND AND AIM

Traditionally lumpectomy as a part of breast-conserving surgery (BCS) is performed by palpation-guided method leading to positive margins and large excision volumes. There is no evidence suggesting that wide margin excisions decrease intra-breast tumour recurrence. Various perioperative techniques are used for margin assessment. We aimed to compare three commonly used techniques, i.e., ultrasound-guided surgery, palpation-guided surgery and cavity shaving for attaining negative margins and estimating the extent of healthy breast tissue resection.

METHOD

A prospective comparative study was performed on 90 patients who underwent breast conservation surgery for early breast cancer between August 2018 and June 2019. Tumour excision with a minimum of 1 cm margin was done either using ultrasound, palpation or cavity shaving. Histopathological evaluation was done to assess the margin status and excess amount of resected normal breast tissue. Calculated resection ratio (CRR) defining the excess amount of the resected breast tissue was achieved by dividing the total resection volume (TRV) by optimal resection volume (ORV). The time taken for excision was also recorded.

RESULTS

Histopathology of all 90 patients (30 in each group) revealed a negative resection margin in 93.3% of 30 patients in palpation-guided surgery group and 100% in both ultrasound-guided surgery and cavity shaving groups. Two patients (6.7%) from the cavity shaving group had positive margins on initial lumpectomy but shave margins were negative. TRV was significantly less in the ultrasound-guided surgery group compared to the palpation-guided surgery group and cavity shaving group (76.9 cm3, 94.7 cm3 and 126.3 cm3 respectively; p < 0.0051). CRR was 1.2 in ultrasound group compared to 1.9 in palpation group and 2.1 in cavity shave group which was also statistically significant (p < 0.0001).Excision time was significantly less (p < 0.001) in palpation-guided surgery group (13.8 min) compared to cavity shaving group (15.1 min) and ultrasound-guided group (19.4 min).

CONCLUSION

Ultrasound-guided surgery is more accurate in attaining negative margins with the removal of least amount of healthy breast tissue compared to palpation-guided surgery and cavity shaving.