Addition of Metastasis-Directed Therapy to Standard of Care Systemic Therapy for Oligometastatic Breast Cancer (EXTEND): A Multicenter, Randomized Phase II Trial

PURPOSE/OBJECTIVE(S)

Prior retrospective and prospective evidence have suggested a potential survival benefit of adding metastasis-directed therapy (MDT) to standard of care systemic therapy for oligometastatic breast cancer. This has led to the increased utilization of MDT in this setting despite the lack of randomized evidence to support this approach. Furthermore, the recent presentation of NRG-BR002 has questioned the value of MDT. Thus, we evaluated whether the addition of MDT to systemic therapy improves PFS in oligometastatic breast cancer.

MATERIALS/METHODS

EXTEND (NCT03599765) is a phase II randomized basket trial for multiple solid tumors testing whether the addition of MDT improves PFS. The primary endpoint was pre-specified to be independently assessed and reported for the breast basket when a minimum of 6 months of follow-up had been reached. Patients with ≤5 metastases were randomized to standard of care systemic therapy with or without MDT. The choice of systemic therapy was at the discretion of the treating medical oncologist. Number of metastatic lesions and prior lines of systemic therapy for metastatic disease were used as stratification variables pre-randomization. The primary endpoint was progression-free survival (PFS) defined as time to randomization to date of clinical or radiographic progression or death. The study was designed to have 80% power to detect an improvement in median PFS from 18 to 36 months, with a type I error of 0.1.

RESULTS

Between September 2018 to July 2022, 43 patients were randomized. 22 patients were assigned to the MDT arm, and 21 patients to the no MDT arm. Three patients were not evaluable. The MDT arm patients were older vs the no-MDT arm patients (median 61.5 years vs 48 years, p = 0.01). Otherwise, the arms were well-balanced. Overall, 8 patients had triple negative disease (18.6%), and 12 patients (30%) had de novo metastatic disease. Of those patients with de novo presentation randomized to MDT, all except one had the primary tumor treated with surgery and radiation. At a median follow-up of 19.4 months, 20 events were observed. Among the 40 evaluable patients, there were 5 deaths (3 in the MDT arm and 2 in the no MDT arm). There was no difference in PFS between the MDT and no MDT arms (median 15.6 v 24.9 months, p = 0.66). Similarly, there was no difference in the secondary endpoint of time to new metastatic lesion appearance between the MDT and no MDT arms (median 15.6 months vs not reached, p = 0.09). Two grade 3 toxicities were observed in the MDT arm, and 1 in the no MDT arm. Further analysis of correlative translational biomarkers, including immune markers and ctDNA, are ongoing.

CONCLUSION

The addition of MDT to standard of care systemic therapy did not improve PFS or time to new metastatic lesion in patients with oligometastatic breast cancer. This data coupled with the recently presented NRG-BR002 results, suggests there is no benefit to MDT in an otherwise unselected oligometastatic breast cancer population.

Evaluation of overall survival and barriers to surgery for patients with breast cancer treated without surgery: a National Cancer Database analysis

Surgery remains the foundation of curative therapy for non-metastatic breast cancer, but many patients do not undergo surgery. Evidence is limited regarding this population. We sought to assess factors associated with lack of surgery and overall survival (OS) in patients not receiving breast cancer surgery. Retrospective cohort study of patients in the US National Cancer Database treated in 2004-2016. The dataset comprised 2,696,734 patients; excluding patients with unknown surgical status or stage IV, cT0, cTx, or pIS, metastatic or recurrent disease resulted in 1,192,294 patients for analysis. Chi-square and Wilcoxon rank-sum tests were used to assess differences between groups. OS was analyzed using the Kaplan-Meier method with a Cox proportional hazards model performed to assess associated factors. In total 50,626 (4.3%) did not undergo surgery. Black race, age >50 years, lower income, uninsured or public insurance, and lower education were more prevalent in the non-surgical cohort; this group was also more likely to have more comorbidities, higher disease stage, and more aggressive disease biology. Only 3,689 non-surgical patients (7.3%) received radiation therapy (RT). Median OS time for the non-surgical patients was 58 months (3-year and 5-year OS rates 63% and 49%). Median OS times were longer for patients who received chemotherapy (80 vs 50 (no-chemo) months) and RT (85 vs 56 (no-RT) months). On multivariate analysis, age, race, income, insurance status, comorbidity score, disease stage, tumor subtype, treatment facility type and location, and receipt of RT were associated with OS. On subgroup analysis, receipt of chemotherapy improved OS for patients with triple negative (HR 0.66, 95% CI 0.59-0.75, P < 0.001) and HER2+ (HR 0.74, 95% CI 0.65-0.84, P < 0.001) subgroups while RT improved OS for ER+ (HR 0.72, 95% CI 0.64-0.82, P < 0.001) and favorable-disease (ER+, early-stage, age >60) (HR 0.61, 95% CI 0.45-0.83, P = 0.002) subgroups. Approximately 4% of women with breast cancer do not undergo surgery, particularly those with more aggressive disease and lower socioeconomic status. Despite its benefits, RT was underutilized. This study provides a benchmark of survival outcomes for patients who do not undergo surgery and highlights a potential role for use of RT.

Abstract ES2-3: Guiding selection of RT approach after lumpectomy

Level I evidence supports the usage of adjuvant radiation therapy following breast conserving surgery for early stage breast cancer. Historically, this was typically delivered using standard fractionation whole breast irradiation. We will review multicenter, randomized controlled trials that support the use of hypofractionation in this setting. More recent level I data has also demonstrated excellent local control with partial breast irradiation for select, early stage breast cancers. In this educational talk we will review the local control and toxicity data for partial breast irradiation. International guidelines on the use of hypofractionated whole breast irradiation and partial breast irradiation will be discussed. We will aim to provide a framework for decision making when electing radiation technique in this setting.

Citation Format: SF Shaitelman. Guiding selection of RT approach after lumpectomy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr ES2-3.

Abstract OT2-04-01: Phase III trial to determine if chest wall and regional nodal radiotherapy (CWRNRT) post mastectomy (Mx) or the addition of RNRT to whole breast RT post breast-conserving surgery (BCS) reduces invasive breast cancer recurrence-free interval (IBCR-FI) in patients (pts) with pathologically positive axillary (PPAx) nodes who are ypN0 after neoadjuvant chemotherapy (NC): NRG Oncology/NSABP B-51/RTOG 1304

This phase III post-NC trial evaluates if CWRNRT post-Mx or whole breast irradiation (WBI) with RNRT after BCS significantly reduces the IBCR-FI rate in pts with PPAx nodes that are pathologically negative after NC. Secondary aims are OS, LRR-FI, DR-FI, DFS-DCIS, second primary cancer, and comparison of RT effect on cosmesis in reconstructed Mx pts. Correlative science examines RT effect by tumor subtype, molecular outcome predictors for residual disease, and predictors for the degree of reduction in loco-regional recurrence.

Methods: Clinical T1-3, N1 IBC PPAx nodes (FNA or core needle biopsy) pts complete ≥8 weeks of NC (anthracycline and/or taxane). HER2+ pts receive anti-HER2 therapy. Following NC, BCS or Mx, sentinel node biopsy (≥2 nodes) and/or Ax dissection with histologically negative nodes is performed. ER/PR and HER-2neu status before NC is required. Pts may receive appropriate adjuvant systemic therapy. Radiation credentialing with a facility questionnaire/case benchmark is required. Random assignment for Mx pts is to no CWRNRT or CWRNRT and for BCS pts to WBI or WBI+RNRT.

Statistics: 1,636 pts are to be enrolled over 5 yrs (definitive analysis at 7.5 yrs). Study is powered at 80% to test that RT reduces the annual hazard rate of events for IBCR-FI by 35% for an absolute risk reduction of 4.6% (5-yr cumulative rate). Intent-to-treat analysis with 3 interim analyses (43, 86, and 129 events) and a 4th/final analysis at 172 events. Pt-reported outcomes focusing on RT effect will be provided by 736 pts before random assignment and at 3, 6, 12, and 24 mos. Accrual as of 6-21-18 is 967 (59.11%).

Contacts: Protocol: CTSU member website https://www.ctsu.org. Questions: NRG Oncology Pgh Clin Coord Dpt: 1-800-477-7227 or ccd@nsabp.org. Pt entry: OPEN at https://open.ctsu.org or the OPEN tab on CTSU member website.

NCT01872975

Support: U10 CA-2166; -180868, -180822; 189867; Elekta

Citation Format: Mamounas EP, Bandos H, White JR, Julian TB, Khan AJ, Shaitelman SF, Torres MA, Vicini FA, Ganz PA, McCloskey SA, Paik S, Gupta N, Li XA, DiCostanzo DJ, Curran WJ, Wolmark N. Phase III trial to determine if chest wall and regional nodal radiotherapy (CWRNRT) post mastectomy (Mx) or the addition of RNRT to whole breast RT post breast-conserving surgery (BCS) reduces invasive breast cancer recurrence-free interval (IBCR-FI) in patients (pts) with pathologically positive axillary (PPAx) nodes who are ypN0 after neoadjuvant chemotherapy (NC): NRG Oncology/NSABP B-51/RTOG 1304 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-04-01.

Abstract P2-11-12: Prospective comparison of late toxicity and cosmetic outcome after accelerated partial breast irradiation with conformal external beam radiotherapy or single-entry multi-lumen intracavitary brachytherapy

Purpose/Objective(s):

To prospectively compare late toxicity after accelerated partial breast irradiation (APBI) with 3D-conformal external beam radiotherapy (3D-CRT) or single-entry multi-lumen intracavitary brachytherapy.

Patients/Methods:

Two hundred eighty-one patients with pTis or pT2N0 (≤3.0 cm) breast cancer treated with segmental mastectomy were prospectively enrolled on a multi-institution observational protocol from 12/2008 – 8/2014. Patients were enrolled and treated at primary, satellite, and affiliated academic institutions. APBI was delivered using 3D-CRT or with a Contura®, MammoSite®, or SAVI® brachytherapy catheter. 3D-CRT patients were treated to 34.0 Gy (7%) or 38.5 Gy (93%) at 3.4-3.85 Gy/fx BID and brachytherapy patients were treated to 34.0 Gy at 3.4 Gy/fx BID. Per protocol, patients were clinically evaluated at 2, 6, 12, 18, and 24 months and then annually. At each clinical evaluation the radiation oncologist scored cosmetic outcome (excellent/good/fair/poor according to the Harvard Cosmesis Scale), toxicity (seroma/infection/fat necrosis/pain/telangiectasia/radiation dermatitis/hyperpigmentation/hypopigmentation/fibrosis/induration/edema/other according to CTCAE v3.0) and recurrence status.

Results:

The median age was 61 years. Of 281 patients, 211 (75%) had invasive breast cancer and 70 (25%) had in situ disease. Among patients with invasive disease, 90% were HR+/HER2-, and among patients with in situ disease, 83% were HR+. APBI was delivered with 3D-CRT in 29 (10%) patients and with single-entry multi-lumen intracavitary brachytherapy in 252 (90%) patients. Among the brachytherapy patients, APBI was delivered with the SAVI®, Contura®, and MammoSite® devices in 176 (70%), 56 (22%), and 20 (8%) patients, respectively. With a median follow-up of 49 months, rates of Grade 1 (G1) and Grade 2-3 (G2-3) toxicity are:

 3D-CRTBrachytherapy   G1G2-3G1G2-3G1G2-3 N (%)N (%)N (%)N (%)  Fibrosis13 (46%)1 (4%)176 (72%)6 (2%)p=0.008p=0.54Fat Necrosis0 (0%)0 (0%)0 (0%)4 (2%)p=1.00p=1.00Telangiectasia6 (21%)1 (4%)44 (18%)5 (2%)p=0.61p=0.48Seroma2 (7%)1 (4%)135 (55%)12 (5%)p&lt;0.0001p=1.00

Mean skin dose of the maximally-irradiated 0.1 cc (D0.1cc) of skin was significantly higher in patients who developed telangiectasia (103.4% ± 16.1% compared to 96.5% ± 18.6% of prescription dose, p=0.007) and fibrosis (100.1% ± 15.5% compared to 92.8% ± 23.0% of prescription dose, p=0.02). Crude rates of fair or poor cosmetic outcome at 2-4 and 4-6 years were 6.9% and 14.8%, respectively, for 3D-CRT and 14.8% and 21.3%, respectively, for brachytherapy (p&gt;0.05 at both timepoints). Five-year recurrence-free survival was 96.3% with 3D-CRT and 96.1% for brachytherapy (p&gt;0.05).

Conclusion:

APBI with single-entry multi-lumen intracavitary brachytherapy is associated with increased rates of grade 1 fibrosis and seroma than APBI with 3D-CRT. Higher mean skin D0.1cc is associated with increased risk of telangiectasia and fibrosis. Despite increased low-grade fibrosis, there is no significant difference in radiation oncologist-reported fair or poor cosmetic outcome out to six years, or rate of five-year ipsilateral breast recurrence.

Citation Format: Stecklein SR, Babiera GV, Bedrosian I, Shaitelman SF, Ballo MT, Tereffe W, Arzu IY, Perkins GH, Strom EA, Reed VK, Dvorak T, Smith BD, Woodward WA, Hoffman KE, Schlembach PJ, Chronowski GM, Shah SJ, Kirsner SM, Nelson CL, Guerra W, Dibaj SS, Bloom ES. Prospective comparison of late toxicity and cosmetic outcome after accelerated partial breast irradiation with conformal external beam radiotherapy or single-entry multi-lumen intracavitary brachytherapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-11-12.

Abstract OT2-03-01: NRG oncology/NSABP B-51/RTOG 1304: A phase III superiority clinical trial designed to determine if chest wall and regional nodal radiotherapy (CWRNRT) post mastectomy (Mx) or the addition of RNRT to breast RT post breast-conserving surgery (BCS) will reduce invasive cancer events in patients (pts) with positive axillary (Ax) nodes and convert to ypN0 after neoadjuvant chemotherapy (NC)

Background:

This phase III post-NC trial evaluates if CWRNRT post Mx or whole breast irradiation (WBI) with RNRT after BCS significantly reduces the invasive breast cancer recurrence-free interval (IBC-RFI) rate in pts presenting with positive Ax nodes that are pathologically negative after NC. Secondary aims are OS, LRRFI, DRFI, DFS-DCIS, and second primary cancer, as well as comparing RT effect on cosmesis in reconstructed Mx pts.

Correlative science studies examine RT effect by tumor subtype, molecular outcome predictors for residual disease pts, and predictors for the degree of reduction in loco-regional recurrence.

Methods:

Clinical T1-3, N1 IBC pts with positive Ax nodes (FNA or core needle biopsy) complete ≥8 wks of NC (anthracycline and/or taxane). HER2-positive pts receive anti-HER2 therapy (tx). After NC, BCS or Mx is performed with a sentinel node biopsy (≥2 nodes) and/or Ax dissection with histologically negative nodes. ER/PR and HER2 neu status before NC is required. Pts receive required systemic tx. Radiation credentialing with a facility questionnaire and a case benchmark is required. Randomization for Mx pts is to no CWRNRT or CWRNRT and for BCS pts to WBI or WBI+RNRT.

Statistics:

1636 pts to be enrolled over 5 yrs with definitive analysis at 7.5 yrs. Study is powered at 80% to test that RT reduces the annual hazard rate of events for IBCR-FI by 35% for an absolute risk reduction in the 5-yr cumulative rate of 4.6%. Intent-to-treat analysis with 3 interim analyses at 43, 86, and 129 events, with a 4th/final analysis at 172 events will occur. Accrual as of 6/13/16 is 356. Pt-reported outcomes focusing on RT effect will be obtained from 736 pts before randomization and at 3, 6, 12, and 24 months.

Contacts:

Protocol: CTSU member website https://www.ctsu.org. Questions: NRG Oncology Pgh Clin Coord Dpt: 1-800-477-7227 or ccd@nsabp.org. Pt entry: OPEN at https://open.ctsu.org or the OPEN tab on CTSU member website.

Support: U10 CA-2166; -180868, -180822; -189867; Elekta.

Citation Format: Mamounas EP, Bandos H, White JR, Julian TB, Khan AJ, Shaitelman SF, Torres MA, Vicini FA, Ganz PA, McCloskey SA, Paik S, Gupta N, Li XA, DiCostanzo DJ, Curran, Jr WJ, Wolmark N. NRG oncology/NSABP B-51/RTOG 1304: A phase III superiority clinical trial designed to determine if chest wall and regional nodal radiotherapy (CWRNRT) post mastectomy (Mx) or the addition of RNRT to breast RT post breast-conserving surgery (BCS) will reduce invasive cancer events in patients (pts) with positive axillary (Ax) nodes and convert to ypN0 after neoadjuvant chemotherapy (NC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-03-01.

Abstract P1-14-04: A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2

Background: Neoadjuvant chemotherapy (NACT) is an integral component for locally advanced and large operable breast cancer. The sequence of taxanes followed by anthracyclines has been the standard of care for almost 20 years. Eribulin (E) is a synthetic analogue of halichondrin B with distinct mechanism of action as microtubule dynamics inhibitor. The FDA approved E in 11/2010 for the treatment of patients (pts) with metastatic breast cancer who have previously received at least two chemotherapeutic regimens for the treatment of metastatic disease. Research Hypothesis: Sequential administration of eribulin followed by FAC/FEC-regimen, would have greater pathologic complete response (pCR) rate than sequential administration of paclitaxel followed by FAC/FEC-regimen as primary systemic therapy for woman with operable breast cancer.

Methods: This is a phase II, randomized, single institution, open label study. Pts were randomized 1:1 to receive E (1.4 mg/m2 d1 and d8 q 21 days x 4) or paclitaxel (P) (80 mg/m2 weekly x12). Both arms received FAC/FEC regimen x 4 doses followed by surgery. Eligible pts were women age 18 or older, Karnosfky PS 80 – 100, histologically confirmed invasive breast cancer, clinical T2-T3, N0-3, M0, HER2-negative. Baseline LVEF of &gt; 50% and normal hematology, liver and kidney laboratory function tests. Primary endpoint was pathologic complete response (pCR/RCB-0) assessed by residual cancer burden (RCB). [Symmans F, 2007]. This protocol (2012-0167) IRB of The University of Texas, MD Anderson Cancer Center.

Results: A preplanned interim analysis aimed to validate trial assumption was conducted after treatment of 54 randomized pts. Between 8/2012 to 7/2014, 54 pts were randomized and 49 were evaluable for pCR(27 P arm and 22 E arm). Tumor response by RCB is shown in the table. pCR rates were 30% and 4.5% in the P and E arm, respectively.

Table 1.ResponsePaclitaxel - FAC/FEC Arm (N=27)Eribulin - FAC/FEC Arm (N=22)RCB 0 (pCR)8 (30%)1 (4.5%)RCB I6 (22.2%)1 (4.5%)RCB II9 (33%)10 (45%)RCB III4 (14.8%)10 (45%)

53 pts were evaluable for toxicity. The combination was safe with mostly grade 1 and 2 toxicities in both arms. In the P arm grade 3 peripheral neuropathy and neutropenia was seen in 3% and 7%, respectively. In the E arm one patient died due to multiorgan failure during cycle 1. There was no other grade 3-5 toxicity. Biomarker analysis using CTCs by AdnaTest Breast were evaluated in 39 pts at baseline. 5/39 pts were positive for CTCs. 3 pts had transcripts for EpCAM, 1 for Muc-1 and another had both. 30 pts had an additional sample post therapy. 2 pts were positive for CTC at baseline as well as at follow up (FU) visit at 180 days. None of the samples showed CTC-EMT at baseline or at FU visits.

Conclusions: The interim analysis demonstrated that E arm lead to significantly lower pCR/RCB1 rate compared to P arm. Ongoing biomarker analyses include TIL, hot spot mutation analysis (HSMA) and molecular inversion probes (MIP) will be presented at the time of the meeting. Clinical trial information: NCT01593020.

Citation Format: Alvarez RH, Koenig KB, Ensor JE, Ibrahim NK, Chavez-MacGregor M, Litton JK, Schwartz Gomez JK, Cyriac A, Krishnamurty S, Caudle AS, Shaitelman SF, Whitman GJ, Booser DJ, Reuben JM, Valero V. A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2. [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 P1-14-04.

Abstract S3-07: Complication and economic burden of local therapy options for early breast cancer

Background: Guideline-concordant local therapy options for early breast cancer include lumpectomy plus whole breast irradiation (lump+WBI), lumpectomy plus brachytherapy (lump+brachy), mastectomy without reconstruction or radiation (mast alone), mastectomy with reconstruction without radiation (mast+recon), and, in older women, lumpectomy without radiation (lump alone). Little is known regarding the comparative complication and economic burden of these options in the general population.

Methods: We used the MarketScan database which includes younger women with private insurance and the SEER-Medicare database which includes older women with Medicare. Women were included if they had early stage disease (T1/2 N0/1 M0) diagnosed in 2000-2011, no prior cancer, and complete insurance coverage from 12 months prior through 24 months after diagnosis. A complication from local therapy was defined as a diagnosis or procedure code for any of the following within 24 months of diagnosis: wound complication, local infection, seroma/hematoma, fat necrosis, breast pain, pneumonitis, rib fracture, and implant removal. Total costs and complication-related costs within 24 months of diagnosis were calculated from a payer's perspective and are reported in 2014 dollars. Logistic regression compared complications by local therapy and generalized linear regression (log link function, gamma distribution) compared complication-related and total costs by local therapy; all models adjusted for relevant covariables.

Results: We selected 44,344 patients from the MarketScan cohort, median age of 53, and 50,562 patients from the SEER-Medicare cohort, median age of 75. For the MarketScan cohort, risk of complications varied as follows: 29% risk in patients treated with lump+WBI (referent), 44% with lump+brachy (adjusted odds ratio [AOR]=2.00;P&lt;.001), 25% with mast alone (AOR=0.85;P&lt;.001), and 54% with mast+recon (AOR=2.89;P&lt;.001). For the SEER-Medicare cohort, risk of complications varied as follows: 37% with lump+WBI (referent), 52% with lump+brachy (AOR=1.91;P&lt;.001), 37% with mast alone (AOR=0.97;P=.17), 65% with mast+recon (AOR=3.17; P&lt;.001), and 30% with lump alone (AOR=0.81; P&lt;.001). Compared to lump+WBI, mean adjusted complication-related cost was $8,085 higher per patient with mast+recon in the MarketScan cohort and $3,711 higher per patient with mast+recon in the SEER-Medicare cohort. In contrast, complication-related costs were similar (+/- $750) for all other local therapy options relative to lump+WBI in both cohorts. For total cost, mast+recon was the most expensive local therapy in the MarketScan cohort, with mean adjusted total cost of $77,321, which was $15,181 more expensive than lump+WBI. In the SEER-Medicare cohort, lump+brachy was the most expensive option ($39,534), followed by mast+recon ($35,269), lump+WBI ($32,562), mast alone ($26,401), and lump alone ($24,455).

Conclusion: Mast+recon results in the highest complication rate and complication-related cost in both younger women and older women with early breast cancer. These findings are relevant to defining which local therapies offer the highest value to patients, payers, and society, and are relevant to patients when evaluating their local therapy options.

Citation Format: Smith BD, Jiang J, Shih Y-CT, Giordano SH, Huo J, Jagsi R, Caudle AS, Hunt KK, Shaitelman SF, Buchholz TA, Shirvani SM. Complication and economic burden of local therapy options for early breast cancer. [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 S3-07.

Abstract P5-14-07: Comparison of infectious complications between breast conserving therapy with catheter-based accelerated partial irradiation and whole breast irradiation

Standard treatment after breast conserving surgery (BCS) has been whole breast irradiation (WBI), however, accelerated partial breast irradiation (APBI) has recently been shown to be an alternative in a select group of patients. APBI has been associated with early postoperative as well as delayed infections. In the current study, we compared rates of infectious complications between patients treated with catheter-based APBI and WBI.

Patients were identified from a single-institution prospective registry from 2009 to 2011. Selection criteria included patients who underwent BCT with either single-entry APBI or WBI and fulfilled criteria for ABPI including ≥50 years, tumor size ≤ 3cm, pN0, and no lympho-vascular invasion. Data regarding treatment, patient comorbidities, and outcomes were obtained. Infectious complications were assessed from the date of APBI catheter insertion or from the date of surgery to start of WBI. Infectious complications were classified as early (≤ 30 days) or delayed (&gt; 30 days). Fisher's exact test was used to compare the rate of infection between APBI and WBI.

91 patients were treated with single-entry catheter-based APBI and 267 patients were treated with WBI. Median follow-up time was 76.2 weeks for APBI patients and 115 weeks for WBI patients. Re-excision was required in 20 patients (21.7%) who underwent APBI and in 51 patients (19.1%) who underwent WBI. Overall, infection occurred in 13 patients (14.1%) who underwent APBI versus 39 patients (14.6%) who underwent WBI. In the APBI group, three (3.3%) patients had infection within 30 days and 10 (10.9%) had infection more than 30 days after catheter insertion. 24 (9.0%) patients had infections within 30 days after surgery and 15 (5.6%) patients occurred more than 30 days after surgery in the WBI group. Patients began WBI within an average of 84 days after surgery. In the APBI group, 4 patients required hospital admission, 5 patients had percutaneous aspiration, and one needed incision and drainage. 8 patients were managed with outpatient oral antibiotics. In the WBI group, 5 patients required hospital admission, 13 patients had percutaneous aspiration, and 30 patients were managed with outpatient oral antibiotics. Diabetes, smoking, and BMI &gt;25 were factors commonly associated with infectious complications in both APBI and WBI but not statistically significant (P = 0.6, 0.09, 0.1. respectively).

In contrast to other studies showing that patients treated with catheter-based APBI have higher rates of infection than patients treated with WBI, our study found no statistically significant difference in infection rates between the two groups. A majority of infections following APBI or WBI can be medically managed as an outpatient basis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-07.

Accelerated partial-breast irradiation using intensity-modulated proton radiotherapy: do uncertainties outweigh potential benefits?

OBJECTIVE

Passive scattering proton beam (PSPB) radiotherapy for accelerated partial-breast irradiation (APBI) provides superior dosimetry for APBI three-dimensional conformal photon radiotherapy (3DCRT). Here we examine the potential incremental benefit of intensity-modulated proton radiotherapy (IMPT) for APBI and compare its dosimetry with PSPB and 3DCRT.

METHODS

Two theoretical IMPT plans, TANGENT_PAIR and TANGENT_ENFACE, were created for 11 patients previously treated with 3DCRT APBI and were compared with PSPB and 3DCRT plans for the same CT data sets. The impact of range, motion and set-up uncertainties as well as scanned spot mismatching between fields of IMPT plans was evaluated.

RESULTS

IMPT plans for APBI were significantly better regarding breast skin sparing (p<0.005) and other normal tissue sparing than 3DCRT plans (p<0.01) with comparable target coverage (p=ns). IMPT plans were statistically better than PSPB plans regarding breast skin (p<0.002) and non-target breast (p<0.007) in higher dose regions but worse or comparable in lower dose regions. IMPT plans using TANGENT_ENFACE were superior to that using TANGENT_PAIR in terms of target coverage (p<0.003) and normal tissue sparing (p<0.05) in low-dose regions. IMPT uncertainties were demonstrated for multiple causes. Qualitative comparison of dose-volume histogram confidence intervals for IMPT suggests that numeric gains may be offset by IMPT uncertainties.

CONCLUSION

Using current clinical dosimetry, PSPB provides excellent dosimetry compared with 3DCRT with fewer uncertainties compared with IMPT.

ADVANCES IN KNOWLEDGE

As currently delivered in the clinic, PSPB planning for APBI provides as good or better dosimetry than IMPT with less uncertainty.

Abstract P4-15-02: Timing of infectious complications following breast conserving therapy with catheter-based accelerated partial breast irradiation

Background: Accelerated partial breast irradiation (APBI) has been introduced as an alternative to whole breast irradiation as part of breast conserving therapy for selected patients. The long-term outcomes remain under investigation. Previous publications have emphasized early postoperative infections with APBI with less focus on delayed infection. In the current study, we evaluated patients enrolled on a prospective registry trial for infectious complications after treatment with catheter-based APBI.

Methods: Patients who underwent single-entry catheter-based APBI were identified from a single-institution prospective registry from 2009 to 2011. Data regarding treatment, patient comorbidities, complications, and outcomes were obtained from registry and retrospective chart review. Infectious complications were assessed from the date of APBI catheter insertion and were classified as early (≤30 days) or delayed (&gt;30 days). All patients were maintained on oral antibiotics while the catheter was in place.

Results: A total of 91 patients with 92 cases of primary breast cancer were enrolled on a prospective registry at a comprehensive cancer center between 2009 and 2011 and treated with single-entry catheter-based APBI. The median follow-up time was 76.2 weeks. A temporary catheter was placed at the time of initial operation in 40 cases (43.5%) and left in place a median of 6 days prior to definitive catheter insertion. There were 20 patients (21.7%) who required re-excision. Overall, breast infection occurred in 13 (14.1%) patients. Three (3.3%) patients had infection within 30 days of catheter placement and 10 (10.9%) occurred more than 30 days after catheter insertion (median 112.5 days, interquartile range 51–154). Eight patients were managed with oral antibiotics alone on an outpatient basis. The remainder required a combination of admission, intravenous antibiotics, and aspiration of abscess. One patient underwent operative drainage.

Conclusion: We found an overall infection rate of 14.1% in patients treated with catheter-based APBI. This is consistent with other reports; however, we found that the majority of infections occurred more than 30 days after definitive catheter placement. Vigilance for infectious complications must continue beyond the immediate treatment period in patients undergoing catheter-based APBI. Most infections following APBI can be managed on an outpatient basis without operative intervention.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-15-02.

Outcomes by breast cancer subtype in patients treated with accelerated partial breast irradiation

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Background: To determine clinical outcomes for patients treated with accelerated partial breast irradiation (APBI) based on breast cancer subtype.

Methods: We evaluated 516 consecutive patients who received APBI with a minimum follow-up of 6 months. Methods of APBI delivery included interstitial brachytherapy (n=221), balloon-based brachytherapy (n=201), and 3D-CRT (n=106). Women were assigned a breast cancer subtype (BCST) based on results of testing for estrogen (ER), progesterone (PR), and human epidermal growth factor (HER2/neu) receptors. Those without test results for all three receptors were excluded. 278 patients were eligible and submitted for analysis. Receptor subtypes were approximated as follows: ER+, PR+/–, and HER-2 negative [luminal A (LA), 164 pts.]; ER+, PR+/–, and HER-2 positive [luminal B (LB), 81 pts.]; ER/PR–, HER-2+ [HER-2 (H2), 5 pts.], and ER/PR/HER-2 negative [basal (B), 28 pts.]. An analysis was then performed to estimate IBTR, RNF, DM, DFS, CSS, and OS.

Results: Mean age was 66 years, median follow-up was 4.9 yrs. Basal and H2 subtype patients had higher histologic grades (Gr. 3 = 75% vs. 10% LA/LB, p<0.001), larger tumors (13.0mm vs. 10.7mm LA/LB, p=0.05), and were more likely to receive chemotherapy (68% vs. 15% LA/LB, p<0.001). Basal subtype patients were also more likely to be African American (18% vs. 4% LA/LB, p=0.002). Margin and nodal status were similar between all BCSTs. At five years, IBTR rates were 2.9%, 3.2%, 0%, and 4.8% for LA, LB, H2, and B subtypes, respectively (p=0.75). The IBTR within the B subtype group was due to a single elsewhere failure, the rate of which was not statistically different than that for the LA subtype (2.9%, p=0.30). DM was only seen in LA (2.5%) and LB (1.4%) (p=0.87). Disease-free survival (95-100%), CSS (97%-100%), and OS (80-100%) (Table) were also not statistically different (p=0.98, 0.85, 0.24, respectively) between BCST categories.

Conclusions: Five-year local control rates after treatment with APBI are excellent for luminal, HER2, and triple-negative phenotypes of early-stage breast cancer. Further study of BCST is important and may be useful when counseling patients on adjuvant treatment options following breast-conserving surgery.

Abstract P4-10-04: Rates of Second Malignancies after Definitive Local Treatment for Ductal Carcinoma In Situ of the Breast

Background: We analyzed the risk of developing second malignancies in patients with ductal carcinoma in situ (DCIS) undergoing surgery and radiotherapy (S+RT) versus surgery alone (S).

Material and Methods: The S+RT cohort consisted of 256 women treated with breast conserving therapy at William Beaumont Hospital. The S cohort consisted of 2,788 women with DCIS in the regional SEER database treated during the same time period. A matched-pair analysis was performed in which each S+RT patient was randomly matched with 8 S patients (total of 2048 patients). Matching criteria included age +/− 2 years. The rates of second malignancies were analyzed overall and as contralateral breast versus non-breast cancers and by organ system. Results: Median follow-up was 13.7 years for the S+RT cohort and 13.3 years for the S cohort. The overall 10-/15-year rate of second malignancies among the S+RT and S cohorts were 14.2%/24.2% and 16.4%/22.6%, respectively (p=0.668). The 15-year second contralateral breast cancer rate was 14.2% in the S+RT cohort and 10.3% in the S cohort (p=0.439). The 15- year risk of a second non-breast malignancy was 14.2% for the S+RT cohort and 13.4% for the S alone cohort (p=0.660). When analyzed by organ system, the 10- and 15-year rates of second malignancies did not differ between the S+RT and the S cohorts for pulmonary, gastrointestinal, central nervous system, gynecological, genitourinary, lymphoid, sarcomatoid, head and neck, or unknown primary tumors.

Discussion: Compared with S alone, S +RT was not associated with an overall increased risk of second malignancies in women with DCIS.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-10-04.