Cannabis Use Patterns among Patients with Early-Stage Breast Cancer in a Large Multicenter Cohort from a State with Legalized Adult Non-Medical Cannabis

PURPOSE/OBJECTIVE(S)

Cannabis use among patients with cancer is an area of great interest given its widespread acceptance despite the lack of supporting clinical data. The absence of data limits the understanding of potential clinical benefits of cannabis and the ability of providers to deliver evidence-based recommendations for patient care. We explored cannabis use patterns in patients with early-stage breast cancer in a large multicenter cohort in a state with legalized adult non-medical cannabis.

MATERIALS/METHODS

Initial questions about cannabis use history and frequency were introduced in Michigan Radiation Oncology Quality Consortium (MROQC) breast cancer patient surveys on 2/1/2020 for female patients receiving radiation after lumpectomy for non-metastatic breast cancer. Expanded questions were introduced on 6/28/2022 to assess mode of administration, active ingredient, and reason for use. Summary statistics were generated. A multivariable model using logistic regression identified patient characteristics associated with cannabis use.

RESULTS

Among 3948 eligible patients, 2738 (69.35%) completed survey questions, and 2462/2738 (89.9%) completed the initial question on cannabis use. Among those, 364/2462 (14.8%) noted cannabis use in the last 30 days, 588 (23.9%) noted remote use (>30 days ago), 1462 (59.4%) reported never having used cannabis, 44 (1.8%) preferred not to answer cannabis use questions, and 4 (0.4%) did not provide use history. Younger age [age <50 vs 60-70, OR 2.5 (95% CI 1.65, 3.79) p<0.001)], Hispanic ethnicity [OR 2.20 (95% CI 1.06, 4.56) p = 0.03], history of smoking [OR 2.56 (95% CI 1.88, 3.48) p<0.001], current smoking [OR 4.70 (95% CI 3.22, 6.86) p<0.001)], and prior chemotherapy [OR 1.40 (95% CI 1.00, 1.96) p = 0.05] predicted recent cannabis use in a multivariable model. Of the 364 patients endorsing cannabis use in the last 30 days, 89 (24.5%), 72 (19.8%), 29 (8.0%), 66 (18.1%), 30 (8.2%), and 78 (21.4%) reported using cannabis 1-2 days, 3-5 days, 6-9 days, 10-19 days, 20-29 days, and all 30 days, respectively. The most common modes of administration among 76 individuals who responded to the expanded questionnaire to date were oral (39.4%), smoking (30.3%), and topical (10.5%). The products used contained tetrahydrocannabinol (THC; 26.3%), cannabidiol (CBD; 19.7%), balanced levels of THC and CBD (19.7%), or active ingredients that were unknown to the patient (34.2%). Patients frequently endorsed cannabis use for insomnia, anxiety, and pain.

CONCLUSION

Many patients with early-stage breast cancer are using cannabis. Younger age, Hispanic ethnicity, smoking, and chemotherapy history are predictors of cannabis use. Patients are often unaware of the active ingredients in the products that they use, suggesting an important role for patient education and a need to equip providers to advise patients in their care.

Shoulder Muscle Dosimetry and Post-Treatment Rehabilitation Utilization for Early-Stage Breast Cancer Patients

PURPOSE/OBJECTIVE(S)

Rehabilitation services for recovery of impaired physical function following breast cancer treatments are largely underutilized. We previously found that breast cancer survivors treated with radiation who received higher radiation doses to the pectoralis major are more likely to self-report shoulder pain and disability. This study aims to address whether radiation dose delivered to the pectoralis major (Pmaj) and pectoralis minor (Pmin) are correlated with referrals for rehabilitation services post-treatment.

MATERIALS/METHODS

A retrospective 1:1 matched case-control study was conducted for breast cancer patients who were and were not referred for breast or shoulder rehabilitation services between 2014-2019 at a single academic institution. Patients were included if they had a lumpectomy and adjuvant radiation without regional nodal irradiation. Cohorts were matched based on age, axillary surgery (none vs. sentinel lymph node biopsy (SLNB)), and use of radiation boost. We used non-parametric Mann-Whitney U tests to determine whether Pmaj or Pmin doses (mean, V50Gy, V45Gy, V40Gy, V35Gy, V30Gy, V20Gy) were different between the two groups. Muscle doses were converted to EQD2 assuming an α/β ratio of 2.5.

RESULTS

In our study of 30 patients of a median age 57 years (IQR 12.75), 20 (66.67%) patients underwent SLNB in addition to lumpectomy. Median tumor size was 1.1cm (range 0.16 - 7.30cm). Stage was 0 for 11 patients (36.67%), I for 14 patients (46.67%), and II for 5 patients (16.67%). 3D conformal radiation was delivered to the whole breast with a moderately hypofractionated (n = 17) or conventionally fractionated regimen (n = 13). The most common rehabilitation diagnoses were lymphedema (n = 8), scar management (n = 7) and shoulder pain (n = 5). Mean dose to both the Pmaj (20.8Gy vs. 18.6Gy; p = 0.02) and Pmin (30.6Gy vs. 24.6Gy; p = 0.01) were significantly higher in patients who received post-treatment rehabilitation compared to those without. The V40Gy, V35Gy, V30Gy and V20Gy (all p<0.02) for the Pmin and V35Gy, V30Gy and V20Gy for the Pmaj (all p<0.04) were also significantly higher in those who underwent rehabilitation.

CONCLUSION

In this cohort of patients with early-stage breast cancer, increased mean doses to the pectoralis muscles were correlated with increased use of rehabilitation services after radiation. Physicians might consider using these dosimetric data to complement clinical symptoms in the decision-making process for referrals for rehabilitation services. This may help facilitate earlier referral to rehabilitation interventions, which is important since early intervention is correlated with improved shoulder morbidity.

Impact of Breast Volume on Achieving a Conservative Heart and Target Coverage Metric for Patients Receiving Whole Breast Radiotherapy in a Statewide Consortium

PURPOSE/OBJECTIVE(S)

Radiation to large breast volumes (BV) has been associated with increased dose inhomogeneities, breast fibrosis, and induration. Radiation exposure to the heart during breast radiotherapy has been associated with late cardiovascular morbidity and mortality. This study, therefore, investigates the impact of BV on achieving optimal lumpectomy cavity target coverage (V95% [%] >95) while maintaining mean heart dose constraints (MHD, mean [Gy] <1) across a range of BV from patients enrolled in a statewide consortium.

MATERIALS/METHODS

A retrospective analysis was conducted for 2,506 patients receiving left-sided whole breast moderately-hypofractionated (2.5-2.8 Gy/fx) radiotherapy without nodal fields between 2018-2022. The BV was calculated for each patient from contours in the treatment planning system, and the volume distribution partitioned into quartiles. Dosimetric parameters were calculated from dose-volume histograms. The percentage of patients in which the metrics were achieved was calculated for each BV quartile for different treatment positions: all positions, supine, supine with breathing motion management, and prone.

RESULTS

The BV ranges within the quartiles (∼620 patients/quartile) were ≤720.0 cc, 720.1 to ≤1065.0 cc, 1065.1 to ≤1500.0 cc, and >1500.0 cc for quartiles Q1-Q4, respectively. Of the 2,506 patients, 76% were treated supine (of which 41.6% were treated using breathing motion management techniques), 23.5% were treated prone, and 0.5% were treated decubitus. Discrete percentages of patients able to meet the metrics are provided in the table. An increase in BV from Q1 to Q4 correlated with lower percentages of patients meeting the MHD metric, however no correlation was observed between BV and target coverage. Treating supine with breathing motion management resulted in a higher percentage of patients meeting the MHD metric (odds ratio (OR) = 1.96 relative to supine without motion management, p<0.0001), while the prone setup proved to be the superior technique across all quartiles (OR = 3.95 relative to supine, p<0.0001).

CONCLUSION

Increasing BVs resulted in lower percentages of patients receiving MHD≤1 Gy. Thus, cardiac sparing may be more difficult to achieve in patients with larger BV. Utilization of alternate treatment positions, such as supine with breathing motion management and prone, greatly improved the percentage of patients able to meet the MHD metric without sacrificing target coverage in all quartiles. Prone positioning was the technique least susceptible to BV effects in meeting the MHD≤1 Gy goal.

Factors Associated with Cardiac Radiation Dose Reduction Following Hypofractionated Radiation Therapy for Localized, Left-Sided Breast Cancer in a Large Statewide Quality Consortium

PURPOSE/OBJECTIVE(S)

Limiting radiation dose to the heart is important for minimizing the risk of long-term cardiac toxicity in patients with left-sided early-stage breast cancer.

MATERIALS/METHODS

Prospectively collected dosimetric data were analyzed for patients undergoing hypofractionated radiation therapy to the left breast for localized node-negative breast cancer within the Michigan Radiation Oncology Quality Consortium (MROQC) from 2016-2022. Goals for limiting cardiac dose were adjusted over time. From 2016-2020, the cardiac quality metric focused on total mean heart dose (MHD) from the composite whole breast and boost plans, tightening from a goal of MHD ≤2 Gy to MHD ≤1.2 Gy by 2020. In 2021-2022, the cardiac metric transitioned to a combined goal of MHD ≤1.0 Gy from the whole breast plan and ≥95% lumpectomy cavity planning target volume (PTV) receiving 95% of the prescription dose. Separate multivariate logistic regression models were developed to assess for covariates associated with meeting the MHD goal in 2016-2020 and combined MHD/PTV coverage goal in 2021-2022.

RESULTS

In total, 4,165 patients were analyzed with a median age of 64 years. Most patients (86%) had either Tis or T1 disease, and 66% received hormone therapy. Baseline demographic and disease characteristics did not change substantially between treatment periods. Use of breath-hold or motion gating increased from 42% in 2016-2020 to 46% in 2021-2022. Similarly, use of prone positioning increased from 12% to 20%. From 2016-2020, 90.9% of plans achieved the MHD goal, compared to 93.6% of plans achieving the composite MHD/PTV goal from 2021-2022. On multivariate analysis in the 2016-2020 cohort, treatment with motion management (OR 5.20, 95% CI [3.59-7.54], p<0.0001) or prone positioning (OR 3.21, 95% CI [1.85-5.57], p < 0.0001) were associated with meeting the MHD goal, while receipt of boost (OR 0.25, 95% CI [0.17-0.39], p<0.0001) and omission of hormone therapy (OR 0.65, 95% CI [0.49-0.88], p = 0.0047), were associated with not meeting the MHD goal. During the era including composite heart dose and PTV coverage goals (2021-2022), treatment with motion management (OR 1.89, 95% CI [1.12-3.21], p = 0.018) or prone positioning (OR 3.71, 95% CI [1.73-7.95], p = 0.0008) were associated with meeting the combined goal, while larger breast volume (≥1440 cc, OR 0.34, 95% CI [0.13 - 0.91], p = 0.031) and treatment at an academic center (OR 0.36, 95% CI [0.22-0.67], p = 0.0009) were associated with not meeting the combined goal.

CONCLUSION

In our statewide consortium, rates of compliance with aggressive targets for limiting cardiac dose remain high, despite tightening of these goals to include lower mean heart doses and inclusion of a concurrent PTV coverage goal. Treatment using motion management or prone positioning is associated with achieving the cardiac dose goals.

Transcriptomic Analysis to Uncover the Mechanism of Radiosensitization of AR-Positive Triple Negative Breast Cancers with AR Inhibition

PURPOSE/OBJECTIVE(S)

The androgen receptor (AR) has been shown to drive tumor growth in triple negative breast cancers (TNBC), and previous work demonstrated AR inhibition as a strategy for radiosensitization in AR-positive (AR+) TNBC. Despite its role in radioresistance, the mechanistic role of AR in response to radiation therapy (RT) remains unknown, as does the benefit of 2nd generation anti-androgens in this context. We hypothesized that all 2nd generation anti-AR therapy would radiosensitize similarly and that canonical AR transcriptional function was responsible for radioresistance in these models.

MATERIALS/METHODS

Radiosensitization was assessed using 2nd generation AR antagonists (apalutamide, enzalutamide, and darolutamide) using clonogenic survival assays in MDA-MB-453, SUM185, MFM-223, and MDA-MB-231 cells at 2-6Gy. Cellular fractionation experiments were performed and quantitated to determine the location of the AR protein in cells treated with AR agonists +/- RT. RNA Seq was performed and transcriptomic approaches were used (Advaita iPathway analysis) to investigate AR-mediated effects in response to RT.

RESULTS

Inhibition with the 2nd generation anti-androgens enzalutamide and apalutamide is sufficient to radiosensitize AR+ TNBC models (rER: 1.34-1.41); while darolutamide had no effect on radiosensitivity (rER: 0.96-1.11). Additionally, TNBC cells with low AR expression were not radiosensitized by AR inhibition with any drug (rER: 0.96-1.03). While stimulation with the synthetic androgen methyltrienolone R1881 is sufficient to induce nuclear translocation of AR in AR+ TNBC cells, AR inhibition with enzalutamide, apalutamide, or darolutamide blocked AR nuclear translocation under growth conditions with charcoal stripped serum or fetal bovine serum. When cells are treated with R1881+RT, nuclear translocation of AR was induced at similar or greater levels compared to R1881 alone in AR+ TNBC cells. Combination treatment of RT with enzalutamide in the presence of hormones reduced nuclear localization of AR (32-39% reduction) compared to RT alone. RNA-sequencing after RT identified transcriptional changes potentially regulated by AR+RT, including changes in the NHEJ pathway genes. Additionally, pathway analyses in these models demonstrated changes in the MAPK/ERK signaling pathway, among others, that may regulate RT resistance in AR+ TNBC models.

CONCLUSION

Most 2nd generation anti-androgens confer radiosensitization in AR+ TNBC models with cellular localization changes of AR noted after RT. The known structural differences amongst 2nd generation anti-androgens may account for differences in radiosensitization noted. Furthermore, AR-mediated radioresistance may be due, at least in part, to downstream MAPK/ERK signaling. This work builds on the mechanistic understanding of AR-mediated radioresistance in AR+ TNBC and may expose vulnerabilities to overcome resistance to combination treatment with AR inhibition and RT.

The HAPPE plus Event-Related (HAPPE+ER) software: A standardized preprocessing pipeline for event-related potential analyses

Event-Related Potential (ERP) designs are a common method for interrogating neurocognitive function with electroencephalography (EEG). However, the traditional method of preprocessing ERP data is manual-editing - a subjective, time-consuming processes. A number of automated pipelines have recently been created to address the need for standardization, automation, and quantification of EEG data pre-processing; however, few are optimized for ERP analyses (especially in developmental or clinical populations). We propose and validate the HAPPE plus Event-Related (HAPPE+ER) software, a standardized and automated pre-processing pipeline optimized for ERP analyses across the lifespan. HAPPE+ER processes event-related potential data from raw files through preprocessing and generation of event-related potentials for statistical analyses. HAPPE+ER also includes post-processing reports of both data quality and pipeline quality metrics to facilitate the evaluation and reporting of data processing in a standardized manner. Finally, HAPPE+ER includes post-processing scripts to facilitate validating HAPPE+ER performance and/or comparing to performance of other preprocessing pipelines in users' own data via simulated ERPs. We describe multiple approaches with simulated and real ERP data to optimize pipeline performance and compare to other methods and pipelines. HAPPE+ER software is freely available under the terms of GNU General Public License at https://www.gnu.org/licenses/#GPL.

Abstract GS4-04: Primary results of NSABP B-39/RTOG 0413 (NRG Oncology): A randomized phase III study of conventional whole breast irradiation (WBI) versus partial breast irradiation (PBI) for women with stage 0, I, or II breast cancer

Background: Conventional WBI after lumpectomy for early-stage breast cancer decreases ipsilateral breast tumor recurrence (IBTR), yielding comparable results to mastectomy. Accelerated PBI appears effective in reducing IBTR by treating only the tumor bed area. As the majority of IBTR occur at or in the vicinity of the tumor bed, we hypothesized that PBI would be as effective as WBI in controlling IBTR. The primary aim of NSABP B-39/RTOG 0413 was to determine if PBI provides equivalent local tumor control post lumpectomy compared to WBI in pts with early-stage breast cancer. The equivalency test was based on a 50% margin of increase in the hazard ratio (HR=1.5). Secondary endpoints included: overall survival (OS), recurrence-free interval (RFI), distant disease-free interval (DDFI), and toxicity.

Methods: Eligible pts had lumpectomy with histologically-free margins and 0-3 positive axillary nodes. Pts were stratified by stage, menopausal status, hormone receptor status, and intent to receive chemotherapy and then randomized to PBI or WBI. PBI was 10 fractions of 3.4-3.85 Gy, given twice daily with either brachytherapy or 3D external beam radiation. WBI was 50 Gy in 2 Gy fractions given daily with a sequential boost to the surgical cavity. Follow-up was every 6 mos for 5 yrs and then annually. All analyses were by intent-to-treat.

Results: From 3-21-05 to 4-16-13, 4216 pts were randomized: 2107 PBI; 2109 WBI. 61% were postmenopausal; 81% were hormone receptor-positive; 29% intended to receive chemotherapy. Stage distribution was: DCIS, 24%; invasive pN0, 65%; invasive pN1, 10%. As of 7-31-18, median follow-up was 10.2 yrs. There were 161 IBTRs as first events: 90 PBI v 71 WBI (HR 1.22; 90%CI 0.94-1.58). Per protocol-defined margin, to declare PBI and WBI equivalent regarding IBTR risk, the 90% CI for the observed HR had to lie entirely between 0.667 and 1.5. The percent of pts IBTR-free at 10 yrs was 95.2% PBI v 95.9% WBI. A statistically significant difference in the 10-yr RFI rate favored WBI (91.9% PBI v 93.4% WBI; HR 1.32; 95%CI 1.04-1.68; p=0.02). No statistically significant differences existed between PBI and WBI in DDFI (HR 1.31; 95%CI 0.91-1.91; p=0.15), OS (HR 1.10; 95%CI 0.90-1.35; p=0.35), or DFS (HR 1.12; 95%CI 0.98-1.29; p=0.11). Grade 3 toxicity was 9.6% PBI v 7.1% WBI, and grade 4-5 toxicity was 0.5% v 0.3%, respectively.

Discussion: PBI did not meet the criteria for equivalence to WBI in controlling IBTR based on the upper limit of the hazard ratio confidence interval. However, the absolute difference in 10-yr rate of IBTR was &lt;1% (4.8% PBI v 4.1% WBI). The risk of an RFI event was statistically significantly higher for PBI compared to WBI, but the absolute difference in 10-yr RFI rate was also small (8.1% PBI v 6.6% WBI). DDFI, OS, and DFS were not statistically different for PBI v WBI. Grade 3-5 toxicities, although low, were more common for PBI than WBI. The trial population was heterogeneous, ranging from Stage 0-2 breast cancer, and outcome by risk categories are being analyzed.

Support: U10CA180868, -180822, UG1CA189867.

Citation Format: Vicini FA, Cecchini RS, White JR, Julian TB, Arthur DW, Rabinovitch RA, Kuske RR, Parda DS, Ganz PA, Scheier MF, Winter KA, Paik S, Kuerer HM, Vallow LA, Pierce LJ, Mamounas EP, Costantino JP, Bear HD, Germaine I, Gustafson G, Grossheim L, Petersen IA, Hudes RS, Curran, Jr. WJ, Wolmark N. Primary results of NSABP B-39/RTOG 0413 (NRG Oncology): A randomized phase III study of conventional whole breast irradiation (WBI) versus partial breast irradiation (PBI) for women with stage 0, I, or II breast cancer [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 GS4-04.

Abstract P5-12-01: A novel gene expression signature prognostic for both locoregional and distant failure and predictive for adjuvant radiotherapy

Background: Most patients with early stage breast cancer (BC) are treated with adjuvant radiotherapy (RT) following breast conserving surgery (BCS) to prevent locoregional recurrences (LRR). No predictive tools are currently available to select patients for RT, resulting in considerable over- and under treatment. We aimed to create and validate a gene expression-based classifier to prognosticate for LRR and to stratify patients for treatment with RT.

Patients and methods: A 27-gene expression signature was developed using three publicly available early stage BC gene expression datasets where patients were treated with RT and had detailed local recurrence information. The largest of the datasets was used to train the signature, and the other two datasets were used for signature refinement. As age was the strongest clinical factor for the endpoint in the training dataset, it was included in the model, resulting in a final clinical-genomic classifier of 27 genes and age. The classifier was locked before external validation in the SweBCG91-RT trial. This phase III clinical trial included primary tumors from 765 patients and for which gene expression data was available. The trial randomized node-negative BC patients to +/- RT following BCS, with sparse use of adjuvant systemic treatment (9%) and a median follow-up of 14.0 years for LRR in patients free from event. The classifier was validated using Cox regression with LRR as the primary endpoint, and hazard ratios (HRs) were calculated using the raw continuous classifier score (range: 0.5 to 2.5).

Results: The novel classifier was highly prognostic for LRR in SweBCG91-RT patients treated with RT (HR=7.5[3.3-16.9], p&lt;0.001), and remained prognostic in multivariate analysis (MVA) that included systemic treatment, subtype and grade (HR=7.2[3.1-16.4], p&lt;0.001). To a lesser extent, the classifier was also prognostic for LRR in patients not treated with RT (HR=1.9[1.0-3.5], p=0.03; MVA HR=1.9[1.0-3.3], p=0.05). Patients at high risk of LRR had a smaller effect of RT, and the treatment predictive potential was confirmed by testing for interaction (pinteraction=0.008). In patients treated with RT, age and the genomic component of the model were both prognostic for LRR (p&lt;0.01) as well as predictive for RT response (pinteraction&lt;0.05) and provided independent information (p&lt;0.01). The combined classifier has increased performance over its individual components (10-year AUC=0.72, 0.67, 0.65 for the classifier, age, and genomic component, respectively). While the novel signature was prognostic for metastasis (HR=4.3[2.3-7.8], p&lt;0.0001), calculated scores from previously published signatures to the metastasis endpoint, including the Oncotype-like score, were not prognostic for LRR.

Conclusions: This novel gene expression signature is highly prognostic for LRR, can identify patients at risk of LRR despite RT, and appears to be treatment predictive for adjuvant RT. Furthermore, the current signature is highly prognostic for metastasis. In contrast, calculated scores of previously published signatures modeled for the metastasis endpoint had inferior performance for LRR. These results underscore both the importance of signatures prognostic for LRR and the similarities in the biology of LRR and distant failure.

Citation Format: Sjöström M, Chang SL, Fishbane N, Davicioni E, Zhao SG, Hartman L, Holmberg E, Feng FY, Speers CW, Pierce LJ, Malmström P, Fernö M, Karlsson P. A novel gene expression signature prognostic for both locoregional and distant failure and predictive for adjuvant radiotherapy [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 P5-12-01.

Abstract P5-15-02: Evaluating the cost of endocrine therapy vs. radiation therapy alone for low risk hormone positive early stage breast cancer in elderly patients

Objective: Elderly patients with low-risk hormone-positive breast cancer are at risk of over treatment. Avoidance of radiation therapy (RT) in favor of endocrine therapy alone was first heralded as the optimal conservative strategy due to logistical simplicity, low acute sequelae and a reduction of contralateral cancers not seen with RT. However, long-term use of aromatase inhibitors (AI) is not without costs and morbidity, often leading to low compliance and notable late effects. We therefore performed a cost-effectiveness analysis to compare the outcomes and costs between AI for five years without RT versus hypofractionated RT alone without endocrine therapy.

Materials and Methods: Using data from available phase III trials and meta-analyses, we constructed a patient-level microsimulation Markov decision model to replicate the comparative outcomes between the strategies above from the societal perspective among 200,000 simulated patients. Five years of anastrozole was compared to a 15-fraction hypofractionated whole breast RT course without boost in a cohort of patients with low-risk disease as defined by CALGB 9343 entry criteria. Noncompliance with AI was modeled from recent population-based data. Relative effectiveness on ipsilateral breast tumor recurrence and contralateral breast cancers were based off the NSABP B-21 trial, adjusted to match the modern outcomes demonstrated in CALGB 9343 and PRIME II with further adjustment for AI over tamoxifen (ATAC, EBCTCG meta-analysis). Indirect costs of travel were accounted for, as were the costs of common and serious side-effects from RT (dermatitis, fibrosis, second malignancy, heart disease) and AI (arthralgia, hot flashes, osteopenia, fracture, thrombosis). A 1-year cycle time and lifetime horizon were used, with all costs adjusted to 2018 US dollars and extracted primarily from Medicare reimbursement data. The primary measure of efficacy was the quality-adjusted life-year (QALY) with age-adjusted utilities extracted from the literature. Half-cycle correction and a 3% discount rate were applied. Probabilistic sensitivity analysis was used to vary all parameters simultaneously.

Results: On average, RT was approximately $3,981 more expensive than endocrine therapy over the lifetime horizon. Under a number of assumptions, RT appeared similar in long-term effectiveness to AI therapy, with a difference of less than 0.03 quality-adjusted life years. Given the low value of the denominator in the incremental cost-effectiveness ratio (ICER), RT did not meet the formally defined $100,000/QALY threshold. On one-way sensitivity analysis, the ICER was particularly sensitive to the incidence and impact of salvage strategies for recurrence, treatment of contralateral breast cancers, cardiac events and fracture rates.

Conclusions: Modeling with the available evidence suggests it is likely that quality-of-life after RT-alone is nearly identical to an AI-alone strategy but associated with a small increase in cost. These results suggest select patients at risk of noncompliance can safely be treated with RT-alone rather than AI alone. Given the relative pros and cons of each strategy, RT-alone should be considered for select elderly low-risk breast patients.

Citation Format: Ward MC, Vicini F, Chadha M, Pierce L, Recht A, Hayman J, Thaker N, Khan A, Keisch M, Shah C. Evaluating the cost of endocrine therapy vs. radiation therapy alone for low risk hormone positive early stage breast cancer in elderly patients [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 P5-15-02.

Abstract P1-12-18: Mechanical properties of the shoulder and pectoralis major in women undergoing breast conserving therapy with axillary dissection and regional nodal radiotherapy versus sentinel node biopsy and radiotherapy to the breast alone

Background: Breast conserving surgery (BCS) and radiotherapy (RT) reduce the risk of breast cancer recurrence, but can cause various functional deficits in breast cancer survivors. Side effects to the shoulder can include pain, stiffness, and restricted mobility, which are difficult to objectively assess in the clinic.

Methods: The mechanical integrity of the shoulder and the pectoralis major (PM) was assessed in patients at least 1 year post-treatment with BCS and RT. Nine patients with node-negative breast cancer were treated with 2 RT fields to the breast alone after BCS and sentinel node biopsy (Group 1). Nine patients with node-positive breast cancer were treated with ≥3 RT fields to the breast and draining lymphatics after BCS and axillary lymph node dissection (ALND) (Group 2). Nodal RT was delivered to the supraclavicular and infraclavicular (level III axillary) nodes in 9/9 patients, the internal mammary nodes in 6/9 patients, and the full axilla (levels I, II, and III) in 1/9 patient. Nine age-matched healthy controls (mean age 54) with no history of breast cancer or shoulder injury were also examined. The mechanical integrity of the shoulder was objectively quantified using robot-assisted biomechanical measures of shoulder stiffness. The shear elastic modulus, or 'stiffness', of the clavicular and sternocostal fiber regions of PM was assessed using ultrasound shear wave elastography. Participants were examined while they were relaxed or actively contracting force with their shoulder muscles. Linear mixed effect models with Bonferroni-corrected multiple comparisons were used to determine if shoulder stiffness or PM shear elastic modulus differed between the two breast cancer groups and controls.

Results: Patients in Groups 1 (mean age 54) and 2 (mean age 57) were an average (SD) 754(111) and 988(163) days since initiating RT (p=0.003). Shoulder stiffness did not differ between the 2 groups and healthy controls (F2,27=0.76, p=0.48), There was a significant group difference in PM shear elastic modulus (F2,27=8.33, p=0.0015), with Group 2 patients exhibiting an average greater stiffness of 14-21% in the sternocostal and 12-28% in the clavicular regions of the PM versus Group 1 patients (p&lt;0.001) and healthy controls (p =0.021). There was no difference between patients treated with Group 1 and controls (p=0.29).

Conclusions: Although power is limited due to small sample size, this study provides the first evidence that the mechanical integrity of the shoulder remains intact in patients who receive ALND combined with a supraclavicular field (generally without full axillary radiotherapy). The observation of altered PM function without subsequent changes to shoulder stiffness in patients treated with ALND and ≥3 RT fields suggests these patients likely develop new neuromuscular strategies to stabilize the shoulder joint to compensate for the PM. Future work is needed to appreciate whether certain muscle strategies are associated with poorer quality of life in breast cancer survivors, and to prospectively monitor the impact of breast cancer treatments on PM mechanical properties.

Citation Format: Lipps DB, Leonardis JM, Lehmann S, Dess RT, McGinnis G, Strauss JB, Hayman JA, Pierce LJ, Jagsi R. Mechanical properties of the shoulder and pectoralis major in women undergoing breast conserving therapy with axillary dissection and regional nodal radiotherapy versus sentinel node biopsy and radiotherapy to the breast alone [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 P1-12-18.

Abstract P1-09-05: Radiosensitization of androgen receptor (AR)-positive triple-negative breast cancer (TNBC) cells using seviteronel (INO-464), a selective CYP17 lyase and AR inhibitor

Background: Increased rates of locoregional recurrence (LR) have been observed in TNBC despite chemotherapy and radiation (RT). A novel radiosensitizer screen nominated the AR as a promising target for treatment of radioresistant breast cancer, including TNBC. We assessed the activity of seviteronel (Sevi), a selective CYP17 lyase and AR inhibitor in Phase 2 clinical development for advanced breast and prostate cancer, as a potential radiosensitizer in AR+ TNBC model.

Methods: Clonogenic survival assays were used to determine the intrinsic RT sensitivity of 21 breast cancer cell (BCC) lines. IC50 values were determined for 130 clinically available compounds and correlation coefficients were calculated using IC50 values and SF-2Gy. Gene expression was measured using RNA Seq or qRT-PCR and protein expression was measured using RPPA arrays. AR function was assessed using functional inhibition with Sevi in MDA-MB-453, ACC-422, ACC-460, SUM-185 (all four AR+ TNBC), MDA-MB-231 (AR- TNBC), and T47D (AR- ER+) BCC lines. Double-stranded DNA (dsDNA) break repair was assessed with γH2AX foci counting. In vivo tumor growth was measured with varying control and treatment groups (16-20 tumors/group). Kaplan-Meier analysis was performed to estimate local control. A Cox proportional hazards model and multi-variate analysis (MVA) were used to determine variables associated with LRF survival.

Results: Our novel radiosensitizer screen identified the activity of anti-androgen therapy as a potentially effective strategy for radiosensitization in RT-resistant BCC lines (R2 =0.46, p-value &lt; 0.01) (Speers et al, J Clin Oncol 35, 2017 (suppl; abstr e12102). Heterogeneity in AR expression was identified in human BCC lines and TNBC samples from patients (N=2098). There was a strong correlation between AR RNA expression and protein expression across all BC intrinsic subtypes. AR inhibition using Sevi induced radiation sensitivity in vitro with an enhancement ratio (ER) of 1.24-1.69 in four different AR+ TNBC lines. No such radiosensitization was seen in AR(-) TNBC or ER+, AR(-) BCC lines. Radiosensitization was at least partially dependent on impaired dsDNA break repair with significant delays in dsDNA break repair at 16 and 24 hours in all AR+ TNBC lines examined (p-value &lt; 0.01). AR inhibition with Sevi significantly radiosensitized AR+ TNBC xenografts in mouse models and markedly delayed tumor-volume tripling time (TTT) and tumor growth (MDA-MB-453: median TTT 16.1 days for RT alone vs. not reached after 45 days for Sevi+RT, p-value &lt;0.001). Similar delays were seen in tumor growth, weight, and tumor doubling. Clinically, TNBC patients whose tumors had higher than median expression of AR had higher rates of LR after RT (HR for LR ˜3, p-value &lt;0.01, 2 independent datasets). In MVA, high AR expression was the variable most significantly associated with worse LR survival after RT in TNBC patients, outperforming all other variables (HR of 3.42; p-value &lt; 0.01).

Conclusions: Our results implicate the AR as a mediator of radioresistance in breast cancer and support the rationale for developing Sevi as a novel radiosensitizing agent in AR+ TNBC.

Citation Format: Speers CW, Chandler B, Olsen E, Wilder-Romans K, Moubadder L, Nyati S, Rae J, Hayes DF, Spratt DE, Wahl DR, Eisner J, Feng FY, Pierce LJ. Radiosensitization of androgen receptor (AR)-positive triple-negative breast cancer (TNBC) cells using seviteronel (INO-464), a selective CYP17 lyase and AR inhibitor [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 P1-09-05.

Abstract P1-10-02: A signature predictive of early vs. late recurrence after radiation treatment (RT) for breast cancer that may inform the biology of early, aggressive recurrences

Purpose: Unmet clinical needs in breast cancer (BC) management include the identification of patients (pts) at high risk to fail locally despite standard local therapy including RT and understanding the biology of these recurrences. We previously reported1 a RT response signature and here extend those studies to identify a signature predictive of timing of recurrence after completion of RT (before or after 3 years).

Methods: Two independent patient cohorts (treated with BCS) from non-randomized clinical trials were used for training and validation. The training cohort included 119 pts with in-breast tumor recurrence and the validation cohort had 25 pts with recurrences. Initial feature selection used Spearman's rank correlation correlating gene expression (14,806 genes) to recurrence time. Genes with sig. correlation (FDR &lt;0.1) and large expression range (fold change &gt;2) were used to train an elastic net penalized Poisson regression model. This model was locked and then applied to the validation dataset. Cox regression was used for both univariate and multivariable analyses (UVA and MVA). To identify biological-related concepts, Spearman's corr. coefficients of recurrence time to gene expression within the training cohort were used to generate a pre-ranked list upon which GSEA pathway analysis was performed.

Results: Spearman's correlation identified 485 genes whose expression was significantly associated with recurrence time (early vs. late). Feature reduction further refined the gene list to 41 genes, which were retained within the signature and locked for further validation. In the training dataset the Spearman's correlation of the continuous score to recurrence time was 0.852 with a P-value of 1.3x10-34 and an AUC of 0.92. Application of this early vs late signature to an independent BC validation set accurately identifies pts with early vs. late recurrences (Spearman's corr.=0.537, p-value&lt;0.007, AUC=0.74, sensitivity=0.71, specificity=0.73, PPV=0.77, NPV=0.67). In UVA and MVA the early vs. late recurrence signature remained the most significant factor associated with recurrence time. Although independent of intrinsic subtype, GSEA analysis of the 41 genes retained within the signature identifies proliferation and EGFR concepts associated with early recurrences and luminal and ER-signaling pathways associated with late recurrences. Knockdown of genes associated with the early and late recurrences is currently underway to assess phenotypic changes (proliferation and clonogenic survival as a measure of early and durable RT response) associated with the early and late recurrence-associated genes.

Conclusion: In this study we derive a BC-specific RT signature predictive of early vs. late recurrence with biologic relevance and validate this signature for prediction of timing of recurrence in an independent clinical dataset. By identifying pts with tumors likely to recur sooner vs. later this signature has the potential to allow for a furthered understanding of the biology underlying early and late recurrences and has a potential to personalize RT, particularly in patients for whom treatment intensification is needed.

1. Clin Cancer Res. 2015 Aug 15;21(16):3667-77.

Citation Format: Speers C, Chang L, Santola A, Liu M, Zhao SG, Chandler B, Olsen E, Bartelink H, Feng FY, Pierce LJ. A signature predictive of early vs. late recurrence after radiation treatment (RT) for breast cancer that may inform the biology of early, aggressive recurrences [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 P1-10-02.

Abstract S4-05: Interrogating the landscape of long noncoding RNAs in breast cancer to identify predictors of tamoxifen resistance

Background: We previously performed an informatics-based analysis on RNA sequencing libraries from 7,256 tumor and normal tissue specimens to delineate the landscape of long noncoding RNAs (lncRNAs) in the human transcriptome. This analysis identified 58,648 lncRNAs, including over 45,000 novel transcripts (Iyer MK et al, Nature Genetics, 2015). We now interrogate this lncRNA compendium to identify top candidate estrogen receptor (ER)-associated lncRNAs in breast cancer and characterize their association with disease progression.

Methods: To prioritize differentially expressed lncRNAs in cancer vs normal tissue, and in ER+ vs ER- disease, we performed Sample Set Enrichment Analysis (SSEA) on &gt;1000 RNA Seq libraries, from breast cancer and normal tissue samples from The Cancer Genome Atlas project. The effect of the top prioritized lncRNA on cancer phenotypes was studied via in vitro proliferation, colony formation, invasion and tamoxifen resistance assays in MCF7 and T47D cells, and via in vivo mouse xenograft studies and chick chorioallantoic membrane (CAM) assays. To study the mechanism by which this lncRNA promotes tumor progression, we identified its top protein interactors and subdomains responsible for function, and then studied the effects of disrupting function of this lncRNA on cancer phenotypes. Finally, in a "guilt-by-association" study, we developed a signature of 150 protein coding genes most strongly associated with our lncRNA of interest, and investigated the association of this signature with clinical outcomes using Oncomine analyses.

Results: SSEA analysis on over 1000 TCGA samples nominated Breast Cancer Associated Transcript (BRCAT 431) as the top overexpressed ER-regulated lncRNA in breast cancer. In vitro experiments demonstrate that siRNA-mediated knockdown of BRCAT431 resulted in significantly decreased proliferation, colony formation, and invasion (by &gt;50% in most assays). Tamoxifen resistance was associated with significantly increased BRCAT431 levels in both MCF7 and T47D cells, and knockdown of BRCAT431 reversed tamoxifen resistance. In vivo xenograft and CAM studies demonstrate that knockdown of BRCAT431 also significantly decreased xenograft growth and tumor invasion by &gt;50%. RNA pulldown followed by mass spectrometry identified the RNA binding protein hnRNPL as a key protein interacting with BRCAT431. Deletion studies identified a 27 base region of BRCAT431 necessary for its interaction with hnRNPL, and loss of this region abrogated BRCAT431- induced invasion. Finally, guilt-by-association studies demonstrate a strong association between BRCAT431 overexpression and tumor grade, recurrence, and metastases.

Conclusion: In this study, we develop the largest reported compendia of breast cancer lncRNAs. We prioritize BRCAT431 as the top lncRNA upregulated in ER-positive breast cancers, and demonstrate that it confers aggressive oncogenic phenotypes in vitro and in vivo. We identify a novel mechanism by which this lncRNA functions. Our results suggest that by promoting tamoxifen resistance, BRCAT431 increases the clinical risk of recurrence and metastases in breast cancer. Overall, this study supports the rationale for investigating lncRNAs as novel biomarkers and therapeutic targets in breast cancer.

Citation Format: Feng FY, Niknafs Y, Han S, Ma T, Speers C, Malik R, Evans J, Zhang C, Pierce LJ, Hayes DF, Rae JM, Chinnaiyan AM. Interrogating the landscape of long noncoding RNAs in breast cancer to identify predictors of tamoxifen resistance. [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 S4-05.

Abstract P6-06-05: RadiotypeDx: Identification and validation of a radiation sensitivity signature in human breast cancer

Purpose: An unmet clinical need in breast cancer (BC) management is the identification of which patients will respond to radiation therapy (RT). We hypothesized that the integration of post-RT clonogenic survival data with gene expression data across a large spectrum of BC cell lines would generate a BC-specific RT sensitivity signature predictive for RT response in BC patients and allow identification of patients with tumors refractive to conventional therapy.

Methods: Using clonogenic survival assays, we identified the range of surviving fraction (SF) after 2 Gy of RT across 21 BC cell lines. Using SF as a continuous variable, the RT sensitivity score (RSS) was correlated to gene expression using a Spearman correlation method on an individual gene basis. Genes were selected for the signature based on positive or negative correlation with a p-value &lt;0.05 and FDR of &lt;0.01. Unsupervised hierarchical clustering identified differences in gene expression across resistant and sensitive cell lines to generate a radiation sensitivity (RS) signature. This signature was trained and validated in a separate human breast tumor dataset (185 pts) containing early stage, node-negative patients treated with surgery and RT alone without adjuvant chemotherapy to assess the predictive effect of RS signature on recurrence risk after RT. Gene function and potentially actionable targets from the signature were validated using clongenic survival and DNA damage assays.

Results: Clonogenic survival identifies a range of radiation sensitivity in human BCC lines (SF 77%-17%) with no significant correlation (r value &lt;0.3) to the intrinsic BC subtype. Using Spearmans correlation method, a total of 126 genes were identified as being associated with radiation sensitivity (72 positively correlated, 54 negatively correlated). Unsupervised hierarchical expression discriminates gene expression patterns in the RT resistant and RT sensitive cell lines and is enriched for genes involved in cell cycle arrest and DNA damage response (enrichment p-value 5.0 E-22). Knockdown of genes associated with the radioresistance signature identifies previously unreported radiation resistance genes, including TACC1 and RND3 with enhancement ratios of 1.25 and 1.37 in BCC lines. Application of this RS signature to an independent breast cancer dataset with clinical outcomes validates the signature and accurately identifies patients with decreased rates of recurrence compared to patients with high expression of the radioresistant signature (p-value &lt;0.0001, misclassification error rate .31, 12/13 patients with locoregional recurrence accurately identified).

Conclusion: In this study, we derive a human BC-specific RT sensitivity signature (RadiotypeDx) with biologic relevance from preclinical studies and validate this signature for prediction of recurrence in an independent clinical dataset. The signature is not correlated to the intrinsic subtypes of human breast cancer and thus provides useful information beyond traditional breast cancer subtyping. By identifying patients with tumors refractory to standard RT, this signature has the potential to allow for personalization of radiotherapy, particularly in patients for whom treatment intensification is needed.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-05.

Abstract P6-04-04: Maternal embryonic leucine zipper kinase (MELK) is a novel radiosensitizing and therapeutic target and is independently prognostic in triple-negative breast cancer

Background: While effective targeted therapies exist for estrogen receptor (ER)-positive and HER2/neu-positive breast cancer, no such effective therapies exist for ER-negative, PR-negative, and HER2-negative (“triple negative”) cancers. Given the lack of targeted agents for triple negative (TN) disease and their relative radiation insensitivity, it is clear that additional targets for treatment are critically needed.

Our previous work identified one such novel molecular target as maternal embryonic leucine zipper kinase (MELK), and we sought to investigate the impact of MELK expression on radiation response and patient outcomes.

Methods: Using gene expression arrays, we interrogated the expression of MELK in 2,061 breast tumor samples as well as a panel of 51 breast cancer cell lines. We measured protein expression in TN cancers with western blotting and used clonogenic survival assays to quantitate radiosensitivity of BCC lines at baseline and after MELK inhibition. Multiple datasets were used to evaluate the prognostic import of MELK. Kaplan-Meier analysis using local control and survival data was performed. Chi squared scores were calculated to determine significance and hazard ratios (HR) and 95% confidence intervals (CI) were calculated. A Cox proportional hazards model was constructed to identify potential factors of survival.

Results: We demonstrate that MELK expression is significantly elevated in human TN breast cancers, including chemoradiation resistant tumors (305 tumors compared to 1756 non-TN breast tumors; p-value 7.5 e-21). MELK protein and RNA expression is induced by ionizing radiation (5.6-7.5 fold at 72 hours, p-value &lt;0.01). We characterized the radiation sensitivity of BCC lines and demonstrated that MELK expression is significantly correlated with radioresistance (as measured by clonogenic survival) in 21 breast cancer cell lines (R: 0.62, p-value 0.003). Inhibition of MELK using both siRNA and small molecule inhibitors induces radiation sensitivity in vitro with and enhancement ratio (ER) of 1.5-1.6. We demonstrate that high MELK expression is strongly correlated with p53 mutation positive status (p-value &lt;0.001). Finally, local control and survival analyses of patients with BC showed that those patients whose tumors have high expression of MELK have significantly higher rates of LR after radiation and an overall poorer prognosis than patients with low expression of MELK (HR for LR 1.89-2.23, p-value 0.001; HR for overall survival 1.46-3.3; p-value &lt;0.001 in 3 independent datasets). In multivariate analysis of all patients, only MELK expression and grade were significantly associated with worse local recurrence free (LRF) survival with a HR of 1.35 (95% CI 1.05-1.72, p-value &lt; 0.01).

Conclusion: Here, we identify MELK as a potential biomarker of radioresistance and target for radiosensitization in triple negative breast cancers. MELK overexpression was associated with local failure across multiple data sets. MVA identified MELK as the strongest factor associated with poor local control. Our results support the rationale for developing clinical strategies to inhibit MELK as a novel target in triple-negative breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-04-04.

Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15-year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomised trials

BACKGROUND

After breast-conserving surgery, radiotherapy reduces recurrence and breast cancer death, but it may do so more for some groups of women than for others. We describe the absolute magnitude of these reductions according to various prognostic and other patient characteristics, and relate the absolute reduction in 15-year risk of breast cancer death to the absolute reduction in 10-year recurrence risk.

METHODS

We undertook a meta-analysis of individual patient data for 10,801 women in 17 randomised trials of radiotherapy versus no radiotherapy after breast-conserving surgery, 8337 of whom had pathologically confirmed node-negative (pN0) or node-positive (pN+) disease.

FINDINGS

Overall, radiotherapy reduced the 10-year risk of any (ie, locoregional or distant) first recurrence from 35·0% to 19·3% (absolute reduction 15·7%, 95% CI 13·7-17·7, 2p<0·00001) and reduced the 15-year risk of breast cancer death from 25·2% to 21·4% (absolute reduction 3·8%, 1·6-6·0, 2p=0·00005). In women with pN0 disease (n=7287), radiotherapy reduced these risks from 31·0% to 15·6% (absolute recurrence reduction 15·4%, 13·2-17·6, 2p<0·00001) and from 20·5% to 17·2% (absolute mortality reduction 3·3%, 0·8-5·8, 2p=0·005), respectively. In these women with pN0 disease, the absolute recurrence reduction varied according to age, grade, oestrogen-receptor status, tamoxifen use, and extent of surgery, and these characteristics were used to predict large (≥20%), intermediate (10-19%), or lower (<10%) absolute reductions in the 10-year recurrence risk. Absolute reductions in 15-year risk of breast cancer death in these three prediction categories were 7·8% (95% CI 3·1-12·5), 1·1% (-2·0 to 4·2), and 0·1% (-7·5 to 7·7) respectively (trend in absolute mortality reduction 2p=0·03). In the few women with pN+ disease (n=1050), radiotherapy reduced the 10-year recurrence risk from 63·7% to 42·5% (absolute reduction 21·2%, 95% CI 14·5-27·9, 2p<0·00001) and the 15-year risk of breast cancer death from 51·3% to 42·8% (absolute reduction 8·5%, 1·8-15·2, 2p=0·01). Overall, about one breast cancer death was avoided by year 15 for every four recurrences avoided by year 10, and the mortality reduction did not differ significantly from this overall relationship in any of the three prediction categories for pN0 disease or for pN+ disease.

INTERPRETATION

After breast-conserving surgery, radiotherapy to the conserved breast halves the rate at which the disease recurs and reduces the breast cancer death rate by about a sixth. These proportional benefits vary little between different groups of women. By contrast, the absolute benefits from radiotherapy vary substantially according to the characteristics of the patient and they can be predicted at the time when treatment decisions need to be made.

FUNDING

Cancer Research UK, British Heart Foundation, and UK Medical Research Council.

Abstract P5-13-02: Impact of Adjuvant Trastuzumab on Local Regional Recurrence: Data from the NCCTG N9831 Study

Background: Trastuzumab (H) improves disease-free survival (DFS) in patients (pts) with HER2 positive breast cancer (BR Ca) when used with adjuvant chemotherapy. We herein compare the rates of local regional recurrence (LRR) in pts randomized to adjuvant chemotherapy with or without adjuvant H.

Methods: The phase 3 randomized trial NCCTG N9831 enrolled 3505 pts with high risk HER2 positive Br Ca to evaluate the effect of adjuvant H on DFS. Pts were randomized to either doxorubicin (A) and cyclophosphamide (C) followed by paclitaxel (T); or AC→TH→H. RT was given concurrently with H after ACT chemotherapy. Pts analyzed underwent lumpectomy (L) + radiotherapy (RT), mastectomy (M) alone, or M+RT. All pts underwent sentinel lymph node biopsy alone and/or axillary dissection. 2816 pts were eligible for competing risk analysis of LRR as a first event (competing risks were distant recurrence, contralateral Br Ca, second primary cancer, or death). Median follow-up is 5.3 years.

Results: Primary breast therapy included L+RT 1062 (38%), M 711 (25%), and M+RT 1043 (37%). Axillary dissection was performed in 90% of pts but less frequently with L+RT (83%) compared to M (88%) or M+RT (98%), chi-sq P&lt;0.001. Stage at presentation was I 41%, II 51%, and III 8% with a significant greater proportion of higher stage pts undergoing M+RT, chi-sq P&lt;0.001. Overall the 5-year LRR rate was 4.1% (95% CI 3.5-4.9%) and similar among the treatment groups: L+RT 4.7% (95% CI 3.6-6.1%), M 3.5% (95% CI 2.4-5.1%), and M+RT 2.3% (95% CI 1.6-3.4%). Among pts with a LRR, 66% were local recurrence only, 11% were local-regional, and 23% were regional only. In the L+RT patients with a LRR, the corresponding rates were 74%, 7%, and 19%, respectively. In the M patients with a LRR, the corresponding rates were 40%, 23%, and 37%, respectively. In the M+RT patients with LRR, the rates were 79%, 4%, and 17%, respectively. H is associated with a non-statistically significant reduction in the risk of LRR for pts who receive L+RT or M+RT (Table 1). No such trend was seen in the M alone group but the number of events was low.

Table 1. LRR According to Local and Adjuvant Treatment Groups

Conclusion: The LRR as the first reported site of failure was low with a median 5. 3 year follow-up. Adjuvant H was associated with a trend of lower LRR in the pts treated with L + RT or M+RT. This observation suggests an additive effect of RT and H on LRR that warrants further investigation. The small number of local-regional events in this one randomized trial supports further investigation of LRR across other adjuvant trastuzumab trials.

Electron imaging of pyrrhotite superstructures

Natural pyrrhotites, when studied by high resolution electron microscopy, yield crystallographic information on a unit cell scale. Structural heterogeneity is prominent. The many reported superstructures are interpretable through an antiphase model. The 5C pyrrhotite superstructure results from an ordered sequence of antiphase domains while the higher temperature NC type results from a disordered sequence.

Local Therapy in BRCA1/2 Carriers with Operable Breast Cancer: Comparison of Breast Conservation and Mastectomy

Background: Women with inherited germline BRCA1/2 mutations have a 55-85% cumulative risk of breast cancer (BC) by age 70. Thus, knowledge of expected outcomes following various treatments is needed to advise these patients should they be diagnosed with BC. It is unclear whether breast conservation (BCT) offers similar rates of tumor control as mastectomy (M) in BRCA1/2 carriers and it is doubtful whether a randomized trial comparing these options could be performed. Thus, this analysis compares the outcomes between similarly staged women with BRCA1/2 mutations treated with BCT vs. M.Methods: Women with deleterious BRCA1/2 mutations diagnosed with operable BC and who consented to longitudinal studies were identified at 10 institutions in the US, Australia, Spain and Israel. Patient, clinical and treatment characteristics were compared between those receiving BCT and those receiving M +/- RT. Time-to-event endpoints included first failure of treatment, diagnosis of contralateral breast cancer (CBC), and overall and BC-specific survival. Cox regression models were constructed to detect significant associations between patient and clinical characteristics and time-to-event endpoints.Results: Clinical characteristics and outcomes for 302 BCT and 353 M patients were compared. With a median F/U of 8.2 years for BCT patients and 8.9 years following M, 15-year local failure as first failure was significantly higher with BCT vs. M (23.5% vs. 5.5%, p&lt;0.0001). Multivariate analysis indicted choice of local therapy as the only factor significantly predicting local recurrence, with a 4.5-fold risk of local failure with BCT compared to M (p&lt;0.0001). Local failure analyses by cohort revealed the presence of a BRCA2 mutation (HR 2.8; p=0.024) and no use of adjuvant chemotherapy (HR 5.4; p=0.0001) as significant predictors within the BCT group; presence of invasive lobular cancer (HR 9.9; p=0.004) was the only significant predictor within the M cohort. No significant differences were seen in distant failure, BC-specific or overall survival by local therapy. 15-year estimates of CBC were 52.1% with BCT; 41.4% with M; and 37.9% with M+RT (p=0.44). Analyses of BCT vs. M +/- RT and surgery +/- RT did not reveal significant differences in CBC by cohort.Conclusions: The higher risk of local failure in BRCA1/2-associated BC treated with BCT compared to M did not translate into an increased risk of distant failure or mortality. RT did not result in a detectable increase in CBC at 15 years above baseline elevated rates. These results at both the involved and contralateral breasts should be discussed when patients with BRCA1/2-associated BC are considering local treatment options.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 959.

Workshop on Partial Breast Irradiation: State of the Art and the Science, Bethesda, MD, December 8-10, 2002

Breast conserving surgery followed by radiation therapy has been accepted as an alternative to mastectomy in the management of patients with early-stage breast cancer. Over the past decade there has been increasing interest in a variety of radiation techniques designed to treat only the portion of the breast deemed to be at high risk for local recurrence (partial-breast irradiation [PBI]) and to shorten the duration of treatment (accelerated partial-breast irradiation [APBI]). To consider issues regarding the equivalency of the various radiation therapy approaches and to address future needs for research, quality assurance, and training, the National Cancer Institute, Division of Cancer Treatment and Diagnosis, Radiation Research Program, hosted a Workshop on PBI in December 2002. Although 5- to 7-year outcome data on patients treated with PBI and APBI are now becoming available, many issues remain unresolved, including clinical and pathologic selection criteria, radiation dose and fractionation and how they relate to the standard fractionation for whole breast irradiation, appropriate target volume, local control within the untreated ipsilateral breast tissue, and overall survival. This Workshop report defines the issues in relation to PBI and APBI, recommends parameters for consideration in clinical trials and for reporting of results, serves to enhance dialogue among the advocates of the various radiation techniques, and emphasizes the importance of education and training in regard to results of PBI and APBI as they become emerging clinical treatments.

Treatment guidelines and techniques in delivery of postmastectomy radiotherapy in management of operable breast cancer

Radiation therapy has been shown to statistically significantly reduce the risk of locoregional recurrence in high-risk patients with operable breast cancer following mastectomy and systemic therapy. Recent trials have also demonstrated a significant survival benefit following radiotherapy in high-risk patients. Therefore, it is important to identify the patients who could potentially derive that survival benefit and to not offer treatment to those patients who are not at increased risk for failure. Established risk factors that predict for increased rates of locoregional recurrence include axillary lymph node involvement and T3 (or T4) disease. While treatment-related factors, such as the extent of the axillary dissection and extent of lymph nodal positivity, also undoubtedly affect locoregional recurrence, additional studies are needed to define the magnitude of their risk. Locoregional patterns of failure have identified the chest wall and supraclavicular/infraclavicular regions to be the most common sites of locoregional failure following mastectomy, which justifies treatment to these regions. While long-term complications are uncommon following locoregional radiotherapy, careful treatment planning is critical to minimize cardiac (and pulmonary) toxicity.

Definition of the supraclavicular and infraclavicular nodes: implications for three-dimensional CT-based conformal radiation therapy

PURPOSE

To delineate with computed tomography (CT) the anatomic regions containing the supraclavicular (SCV) and infraclavicular (IFV) nodal groups, to define the course of the brachial plexus, to estimate the actual radiation dose received by these regions in a series of patients treated in the traditional manner, and to compare these doses to those received with an optimized dosimetric technique.

MATERIALS AND METHODS

Twenty patients underwent contrast material-enhanced CT for the purpose of radiation therapy planning. CT scans were used to study the location of the SCV and IFV nodal regions by using outlining of readily identifiable anatomic structures that define the nodal groups. The brachial plexus was also outlined by using similar methods. Radiation therapy doses to the SCV and IFV were then estimated by using traditional dose calculations and optimized planning. A repeated measures analysis of covariance was used to compare the SCV and IFV depths and to compare the doses achieved with the traditional and optimized methods.

RESULTS

Coverage by the 90% isodose surface was significantly decreased with traditional planning versus conformal planning as the depth to the SCV nodes increased (P < .001). Significantly decreased coverage by using the 90% isodose surface was demonstrated for traditional planning versus conformal planning with increasing IFV depth (P = .015). A linear correlation was found between brachial plexus depth and SCV depth up to 7 cm.

CONCLUSION

Conformal optimized planning provided improved dosimetric coverage compared with standard techniques.

Mammographically detected ductal carcinoma in situ of the breast treated with breast-conserving surgery and definitive breast irradiation: long-term outcome and prognostic significance of patient age and margin status

PURPOSE

This study was performed to determine the long-term outcome for women with mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast treated with breast-conserving surgery followed by definitive breast irradiation.

METHODS AND MATERIALS

An analysis was performed of 422 mammographically detected intraductal breast carcinomas in 418 women from 11 institutions in North America and Europe. All patients were treated with breast-conserving surgery followed by definitive breast irradiation. The median follow-up time was 9.4 years (mean, 9.4 years; range, 0.1-19.8 years).

RESULTS

The 15-year overall survival rate was 92%, and the 15-year cause-specific survival rate was 98%. The 15-year rate of freedom from distant metastases was 94%. There were 48 local failures in the treated breast, and the 15-year rate of any local failure was 16%. The median time to local failure was 5.0 years (mean, 5.7 years; range, 1.0-15.2 years). Patient age at the time of treatment and final pathology margin status from the primary tumor excision were both significantly associated with local failure. The 10-year rate of local failure was 31% for patient age < or = 39 years, 13% for age 40-49 years, 8% for age 50-59 years, and 6% for age > or = 60 years (p = 0.0001). The 10-year rate of local failure was 24% when the margins of resection were positive, 9% when the margins of resection were negative, 7% when the margins of resection were close, and 12% when the margins of resection were unknown (p = 0.030). Patient age < or = 39 years and positive margins of resection were both independently associated with an increased risk of local failure (p = 0.0006 and p = 0.023, respectively) in the multivariable Cox regression model.

CONCLUSIONS

The 15-year results from the present study demonstrated high rates of overall survival, cause-specific survival, and freedom from distant metastases following the treatment of mammographically detected ductal carcinoma in situ of the breast using breast-conserving surgery and definitive breast irradiation. Younger age and positive margins of resection were both independently associated with an increased risk of local failure. The 15-year results in the present study serve as an important benchmark for comparison with other treatment modalities. These results support the use of breast-conserving surgery and definitive breast irradiation for the treatment of appropriately selected patients with mammographically detected ductal carcinoma in situ of the breast.

Observations of residual differentiation potential during lineage commitment

We have recently described a subset of the multipotent progenitor pool that contains a common lymphoid progenitor. This subset of cells is lineage negative and expresses c-kit and Sca-1, but lacks expression of Thy 1.1 (Thyneg). Based on the observation that lethally irradiated mice transplanted with these cells die from anemia unless supported with competitor marrow, we hypothesized that these progenitors lacked erythroid potential. We analyzed the erythroid potential of these cells by transplanting them into mice allelic at the hemoglobin locus and compared their erythroid potential with the Thy-1.1low (Thylow) subset that contains hematopoietic stem cells. We also performed CFU-C assays in methylcellulose containing recombinant cytokines and determined erythroid contribution to colonies using in situ benzidine staining. Donor-derived hemoglobin was observed following transplant of Thyneg cells, even though 19 of 20 of these animals died from anemia. In contrast, recipients of Thylow cells showed complete donor-derived engraftment 30 days following transplant. While approximately 60% of day 4 colonies derived from Thyneg cells expressed hemoglobin, by day 11 less than 5% were hemoglobinized. In contrast, greater than 70% of the Thylow subset contained hemoglobinized cells at the end of the observation period. A similar transient appearance of myeloid progeny was also observed in colonies derived from c-kitlow Thyneg lymphoid progenitor cells. We conclude that these studies demonstrate commitment to the lymphoid lineage at the Thylow-to-Thyneg interface, and that the loss of erythroid and myeloid potential is gradual rather than abrupt. Hemoglobinized colonies may be undergoing apoptosis because of down-regulation of GATA-1 or because of a death signal from surrounding nonerythrocytic cells.

Salvage treatment for local recurrence after breast-conserving surgery and radiation as initial treatment for mammographically detected ductal carcinoma in situ of the breast

BACKGROUND

The purpose of the current study is to evaluate the outcome of salvage treatment for local recurrence after breast-conserving surgery and radiation as initial treatment for mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast.

METHODS

An analysis was performed of 42 patients with local only first failure (n = 41) or local-regional only first failure (n = 1) after breast-conserving surgery and radiation treatment had been given for DCIS of the breast. Surgical treatment at the time of local recurrence included mastectomy (n = 37; 88%) or excision (n = 5; 12%). Adjuvant systemic therapy at the time of local recurrence was chemotherapy (n = 3; 7%), tamoxifen (n = 8; 19%), both (n = 1; 2%), none (n = 29; 69%), or unknown (n = 1; 2%). The median interval from the time of initial treatment to local recurrence was 4.8 years (range = 1.0-15.2 yrs). The median follow-up after salvage treatment was 4.5 years (range = 0.2-12.8 yrs).

RESULTS

At the time of the local recurrence, 22 patients (52%) had invasive ductal carcinoma, 18 patients (43%) had DCIS, 1 patient (2%) had invasive lobular carcinoma, and 1 patient (2%) had angiosarcoma. After salvage treatment, the rate of overall survival and the rate of cause specific survival for all 42 patients were 92% at both 5- and 8-years after treatment. The rate of freedom from distant metastases was 89% at 5 and 8 years. Favorable prognostic factors after salvage treatment were DCIS as the histology of the local recurrence and mammography only as the method of detection of the local recurrence.

CONCLUSIONS

The results of salvage treatment in the current study demonstrated that local recurrences were salvaged with high rates of survival and freedom from distant metastases. These results support the use of breast-conserving surgery and radiation for initial management of DCIS of the breast.

Complications and patient satisfaction following expander/implant breast reconstruction with and without radiotherapy

PURPOSE

To compare the rates of complications and patient satisfaction among breast cancer patients treated with mastectomy and tissue expander/implant reconstruction with and without radiotherapy.

METHODS AND MATERIALS

As part of the Michigan Breast Reconstruction Outcome Study (MBROS), breast cancer patients undergoing mastectomy with reconstruction were prospectively evaluated with respect to complications, general patient satisfaction with reconstruction, and esthetic satisfaction. Included in this study was a cohort of women who underwent breast reconstruction using an expander/implant (E/I). A subset of these patients also received radiotherapy (RT). At 1 and 2 years postoperatively, a survey was administered which included 7 items assessing both general satisfaction with their reconstruction and esthetic satisfaction. Complication data were also obtained at the same time points using hospital chart review. Radiotherapy patients identified in the University of Michigan Radiation Oncology database that underwent expander/implant reconstruction but not enrolled in the MBROS study were also added to the analysis.

RESULTS

Eighty-one patients underwent mastectomy and E/I reconstruction. Nineteen patients received RT and 62 underwent reconstruction without RT. The median dose delivered to the reconstructed breast/chest wall, including boost, was 60.4 Gy (range, 50.0-66.0 Gy) in 1.8- to 2.0-Gy fractions. With a median follow-up of 31 months from the date of surgery, complications occurred in 68% (13/19) of the RT patients compared to 31% (19/62) in the no RT group (p = 0.006). Twelve of 81 patients (15%) had a breast reconstruction failure. Reconstruction failure was significantly associated with experiencing a complication (p = 0.0001) and the use of radiotherapy (p = 0.005). The observed reconstruction failure rates were 37% (7/19) and 8% (5/62) for patients treated with and without radiotherapy, respectively. Tamoxifen was associated with a borderline risk of complications (p = 0.07) and a significant risk of reconstruction failure (p = 0.01). Sixty-six patients of the study group completed the satisfaction survey; 15 patients did not. To offset potential bias for patients not completing the survey, we analyzed satisfaction data assuming "dissatisfaction" scores for surveys not completed. In the analysis of patients with unilateral E/I placement, reconstruction failure was significantly associated with a lower general satisfaction (p = 0.03). Ten percent of patients experiencing a reconstruction failure were generally satisfied compared to 23% who completed E/I reconstruction. In addition, tamoxifen use was associated with a significantly decreased esthetic satisfaction (p = 0.03). Radiotherapy was not associated with significantly decreased general or esthetic satisfaction.

CONCLUSION

Irradiated patients had a higher rate of expander/implant reconstruction failure and complications than nonirradiated patients. Despite these differences, our pilot data suggest that both general satisfaction and patient esthetic satisfaction were not significantly different following radiotherapy compared to patients who did not receive RT. Although statistical power was limited in the present study and larger patient numbers are needed to validate these results, this study suggests comparable patient assessment of cosmetic outcome with or without radiotherapy in women who successfully complete expander/implant reconstruction.

Phenotypic distinction and functional characterization of pro-B cells in adult mouse bone marrow

A lymphoid-committed progenitor population was isolated from mouse bone marrow based on the cell surface phenotype Thy-1.1(neg)Sca-1(pos)c-Kit(low)Lin(neg). These cells were CD43(pos)CD24(pos) on isolation and proliferated in response to the cytokine combination of steel factor, IL-7, and Flt3 ligand. Lymphoid-committed progenitors could be segregated into more primitive and more differentiated subsets based on expression of AA4.1. The more differentiated subset generated only B lymphoid cells in 92% of total colonies assayed, lacked T lineage potential, and expressed Pax5. These studies have therefore defined and isolated a B lymphoid-committed progenitor population at a developmental stage corresponding to the initial expression of CD45R.

Effect of radiotherapy after breast-conserving treatment in women with breast cancer and germline BRCA1/2 mutations

PURPOSE

Recent laboratory data suggest a role for BRCA1/2 in the cellular response to DNA damage. There is a paucity of clinical data, however, examining the effect of radiotherapy (RT), which causes double-strand breaks, on breast tissue from BRCA1/2 mutation carriers. Thus the goals of this study were to compare rates of radiation-associated complications, in-breast tumor recurrence, and distant relapse in women with BRCA1/2 mutations treated with breast-conserving therapy (BCT) using RT with rates observed in sporadic disease.

PATIENTS AND METHODS

Seventy-one women with a BRCA1/2 mutation and stage I or II breast cancer treated with BCT were matched 1:3 with 213 women with sporadic breast cancer. Conditional logistic regression models were used to compare matched cohorts for rates of complications and recurrence.

RESULTS

Tumors from women in the genetic cohort were associated with high histologic (P =.0004) and nuclear (P =.009) grade and negative estrogen (P=.0001) and progesterone (P=.002) receptors compared with tumors from the sporadic cohort. Using Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity scoring, there were no significant differences in acute or chronic morbidity in skin, subcutaneous tissue, lung, or bone. The 5-year actuarial overall survival, relapse-free survival, and rates of tumor control in the treated breast for the patients in the genetic cohort were 86%, 78%, and 98%, respectively, compared with 91%, 80%, and 96%, respectively, for the sporadic cohort (P = not significant).

CONCLUSION

There was no evidence of increased radiation sensitivity or sequelae in breast tissue heterozygous for a BRCA1/2 germline mutation compared with controls, and rates of tumor control in the breast and survival were comparable between BRCA1/2 carriers and controls at 5 years. Although additional follow-up is needed, these data may help in discussing treatment options in the management of early-stage hereditary breast cancer and should provide reassurance regarding the safety of administering RT to carriers of a germline BRCA1/2 mutation.

Rapid, B lymphoid-restricted engraftment mediated by a primitive bone marrow subpopulation

Utilizing multiparameter flow cytometry, we have defined a subset of bone marrow cells containing lymphoid-restricted differentiation potential after i.v. transplantation. Bone marrow cells characterized by expression of the Sca-1 and c-kit Ags and lacking Ags of differentiating lineages were segregated into subsets based on allele-specific Thy-1.1 Ag expression. Although hematopoietic stem cells were recovered in the Thy-1.1low subset as previously described, the Thy-1.1neg subset consisted of progenitor cells that preferentially reconstituted the B lymphocyte lineage after i.v. transplantation. Recipients of Thy-1.1neg cells did not survive beyond 30 days, presumably due to the failure of erythroid and platelet lineages to recover after transplants. Thy-1.1neg cells predominantly reconstituted the bone marrow and peripheral blood of lethally irradiated recipients with B lineage cells within 2 weeks, although a low frequency of myeloid lineage cells was also detected. In contrast, myeloid progenitors outnumbered lymphoid progenitors when the Thy-1.1neg population was assayed in culture. When Thy-1. 1low stem cells were rigorously excluded from the Thy-1.1neg subset, reconstitution of T lymphocytes was rarely observed in peripheral blood after i.v. transplantation. Competitive repopulation studies showed that the B lymphoid reconstitution derived from Thy-1.1neg cells was not sustained over a 20-wk period. Therefore, the Thy-1. 1neg population defined in these studies includes transplantable, non-self-renewing B lymphocyte progenitor cells.