89Zr-Trastuzumab PET/CT Imaging of HER2-Positive Breast Cancer for Predicting Pathological Complete Response after Neoadjuvant Systemic Therapy: A Feasibility Study

BACKGROUND

Approximately 20% of invasive ductal breast malignancies are human epidermal growth factor receptor 2 (HER2)-positive. These patients receive neoadjuvant systemic therapy (NAT) including HER2-targeting therapies. Up to 65% of patients achieve a pathological complete response (pCR). These patients might not have needed surgery. However, accurate preoperative identification of a pCR remains challenging. A radiologic complete response (rCR) on MRI corresponds to a pCR in only 73% of patients. The current feasibility study investigates if HER2-targeted PET/CT-imaging using Zirconium-89 (89Zr)-radiolabeled trastuzumab can be used for more accurate NAT response evaluation.

METHODS

HER2-positive breast cancer patients scheduled to undergo NAT and subsequent surgery received a 89Zr-trastuzumab PET/CT both before (PET/CT-1) and after (PET/CT-2) NAT. Qualitative and quantitative response evaluation was performed.

RESULTS

Six patients were enrolled. All primary tumors could be identified on PET/CT-1. Four patients had a pCR and two a pathological partial response (pPR) in the primary tumor. Qualitative assessment of PET/CT resulted in an accuracy of 66.7%, compared to 83.3% of the standard-of-care MRI. Quantitative assessment showed a difference between the SUVR on PET/CT-1 and PET/CT-2 (ΔSUVR) in patients with a pPR and pCR of -48% and -90% (p = 0.133), respectively. The difference in tumor-to-blood ratio on PET/CT-1 and PET/CT-2 (ΔTBR) in patients with pPR and pCR was -79% and -94% (p = 0.133), respectively. Three patients had metastatic lymph nodes at diagnosis that were all identified on PET/CT-1. All three patients achieved a nodal pCR. Qualitative assessment of the lymph nodes with PET/CT resulted in an accuracy of 66.7%, compared to 50% of the MRI.

CONCLUSIONS

NAT response evaluation using 89Zr-trastuzumab PET/CT is feasible. In the current study, qualitative assessment of the PET/CT images is not superior to standard-of-care MRI. Our results suggest that quantitative assessment of 89Zr-trastuzumab PET/CT has potential for a more accurate response evaluation of the primary tumor after NAT in HER2-positive breast cancer.

Excision of both pretreatment marked positive nodes and sentinel nodes improves axillary staging after neoadjuvant systemic therapy in breast cancer

BACKGROUND

Marking the axilla with radioactive iodine seed and sentinel lymph node (SLN) biopsy have been proposed for axillary staging after neoadjuvant systemic therapy in clinically node-positive breast cancer. This study evaluated the identification rate and detection of residual disease with combined excision of pretreatment-positive marked lymph nodes (MLNs) together with SLNs.

METHODS

This was a multicentre retrospective analysis of patients with clinically node-positive breast cancer undergoing neoadjuvant systemic therapy and the combination procedure (with or without axillary lymph node dissection). The identification rate and detection of axillary residual disease were calculated for the combination procedure, and for MLNs and SLNs separately.

RESULTS

At least one MLN and/or SLN(s) were identified by the combination procedure in 138 of 139 patients (identification rate 99·3 per cent). The identification rate was 92·8 per cent for MLNs alone and 87·8 per cent for SLNs alone. In 88 of 139 patients (63·3 per cent) residual axillary disease was detected by the combination procedure. Residual disease was shown only in the MLN in 20 of 88 patients (23 per cent) and only in the SLN in ten of 88 (11 per cent), whereas both the MLN and SLN contained residual disease in the remainder (58 of 88, 66 per cent).

CONCLUSION

Excision of the pretreatment-positive MLN together with SLNs after neoadjuvant systemic therapy in patients with clinically node-positive disease resulted in a higher identification rate and improved detection of residual axillary disease.

Abstract GS4-01: Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: 10 year follow up results of the EORTC AMAROS trial (EORTC 10981/22023)

Background: Sentinel node biopsy (SNB) is standard in assessing axillary lymph node status in patients with clinically node-negative breast cancer. The 5-year analysis of AMAROS trial showed that if locoregional treatment is advised after a tumor-positive axillary SNB, axillary radiotherapy (ART) is a reasonable alternative for an axillary lymph node dissection (ALND) with less side effects, though follow up was relatively short. Here we present the 10-year follow up data.

Methods: From February 2001 to April 2010, patients with primary breast cancer stage cT1-2N0M0 were enrolled in the EORTC phase III non-inferiority AMAROS trial by 34 European sites. Patients were randomized between ALND and ART in case of a tumor-positive SNB. The primary endpoint, axillary recurrence rate (AxR) is now assessed at 10 years in the ITT population using Fine and Gray cumulative incidence method with deaths as competing risks, as well as secondary endpoints: overall survival (OS), distant metastasis free survival (DMFS), second primaries (including cancers other than breast cancers and contralateral DCIS) and locoregional recurrences (LRR). Little extra information beyond 5 years was available concerning Quality of Life and morbidity. Data collection is still ongoing and will be presented later.

Results:Of the 4806 patients entered, 1425 patients had a tumor-positive SNB: 744 in the ALND-arm and 681 in the ART-arm, 60% with a macrometastasis. Both treatment-arms achieved a median 10-year follow-up and were comparable regarding age, tumor size, grade, tumor type and adjuvant systemic treatment. In the group who had ALND, the 5-year AxR was 0.41% (95%CI: 0.00;0.88) (4/744) and the 10-year AxR was 0.93% (95%CI:0.18;1.68) (7/744). In the group who had ART, the 5-year AxR was 1.04% (95%CI: 0.27;1.81) (7/681) and the 10-year AxR was 1.82% (95%CI: 0.74;2.94) (11/681) (HR 1.71, 95%CI: 0.67;4.39, p = 0.37). Sensitivity analysis, considering deaths and distant recurrences as competing risks, revealed consistent results. There were no significant differences between treatment arms regarding OS (ALND: 84.6% (95%CI: 81.5;87.1), ART: 81.4% (95%CI: 77.9;84.4), HR 1.17, 95%CI: 0.89;1.52, p= 0.26) and DMFS (ALND: 81.7% (95%CI: 78.5;84.4), ART: 78.2% (95%CI: 74.6;81.3), HR 1.18, 95%CI: 0.92;1.50, p=0.19). Cumulative incidence estimates of 10-year LRR are 3.59% (95%CI: 2.12;5.06) (ALND) versus 4.07% (95%CI: 2.49;5.65) (ART) (p= 0.69). More second primaries were observed after ART: 75/681 (21 contralateral breast) as compared to ALND: 57/744 (11 contralateral breast) (p = 0.035). All results are consistent in the per protocol analysis of patients with a tumor-positive SNB.

Conclusion: Axillary recurrence after 10 years in patients with a tumor-positive SNB who were treated with ART is extremely rare and not significantly different from patients who were treated with ALND. OS, DMFS and locoregional control are also comparable. Second primaries including contralateral breast cancers are more frequently encountered after ART, but the difference is still low in absolute numbers. Thus, ART is a safe treatment for breast cancer patients with a tumor-positive SNB.

Citation Format: Rutgers EJ, Donker M, Poncet C, Straver ME, Meijnen P, van de Velde CJ, Mansel RE, Blanken C, Orzalesi L, Klinkenbijl JH, van der Mijle HC, Veltkamp SC, van 't Riet M, Albregts M, Marinelli A, Rijna H, Tobon Morales R, Snoj M, Bundred N, Chauvet MP, Merkus JW, Petignat P, Schinagl DA, Coens C, Peric A, Bogaerts J, van Tienhoven G. Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer patients: 10 year follow up results of the EORTC AMAROS trial (EORTC 10981/22023) [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 GS4-01.

Combined PET-CT and axillary lymph node marking with radioactive iodine seeds (MARI procedure) for tailored axillary treatment in node-positive breast cancer after neoadjuvant therapy

BACKGROUND

The treatment of axillary lymph node metastases after neoadjuvant systemic therapy (NST) remains debatable and axillary lymph node dissection (ALND) is still the standard of care. Marking axillary lymph nodes with radioactive iodine seeds (MARI procedure) is accurate in restaging the axilla after NST (false-negative rate 7 per cent). Here, the potential of tailored axillary treatment, determined by combining the results of PET-CT before NST with those of the MARI procedure after NST, was analysed.

METHODS

A cohort of axillary node-positive patients was used to construct a hypothetical treatment algorithm based on a combination of PET-CT and the MARI procedure. In the algorithm, the number of fluorodeoxyglucose (FDG)-avid axillary lymph nodes (1-3 versus 4 or more) before NST and the tumour status of the MARI node (positive versus negative) after NST were used to tailor axillary treatment. All patients in the cohort underwent ALND, allowing estimation of potential overtreatment and undertreatment.

RESULTS

A total of 93 patients were included in the study. Between one and three FDG-avid axillary lymph nodes were observed in 59 patients, and four or more in 34 patients. The MARI node was tumour-negative in 32 patients and showed residual disease in 61. Treatment according to the constructed algorithm would have resulted in 74 per cent of patients avoiding an ALND, with potential undertreatment in three patients (3 per cent) and overtreatment in 16 (17 per cent).

CONCLUSION

Tailored axillary treatment after NST in node-positive patients, by combining PET-CT before NST and the MARI procedure after NST, has the potential for ALND to be avoided in 74 per cent of patients.

Characterisation of multifocal breast cancer using the 70-gene signature in clinical low-risk patients enrolled in the EORTC 10041/BIG 03-04 MINDACT trial

BACKGROUND

In multifocal breast cancer, guidelines recommend basing adjuvant systemic treatment decisions on characteristics of the largest lesion, disregarding multifocality as an independent prognosticator. We assessed the association between multifocal disease and both the 70-gene signature (70-GS), and distant metastasis-free survival (DMFS) in clinical low-risk breast cancer patients enrolled in the European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 Microarray In Node-negative and 1 to 3 positive lymph node Disease may Avoid ChemoTherapy (MINDACT) trial.

PATIENTS AND METHODS

The analysed population consisted of enrolled patients in the MINDACT trial with clinical low-risk disease, defined by a modified Adjuvant! Online cut-off for the 10-year risk of recurrent disease or death. Eligibility criteria of MINDACT dictate that patients with multifocal disease could be included if the different lesions had similar pathological characteristics. The presence of multifocal disease was deducted from the case report form (CRF)-question for sum of diameter for all invasive tumour foci. Clinicopathological characteristics and gene expression of patients with unifocal and multifocal (largest lesion) disease were compared. Subsequently, the association between multifocal disease and the 70-GS was evaluated as well as the association between multifocality and 5-year DMFS.

RESULTS

The study included 3090 clinical low-risk patients with unifocal and 238 patients with multifocal disease. Apart from a higher prevalence of lobular tumours (21.8% versus 10.8%, by local pathology), we did not observe differences in baseline characteristics between multifocal and unifocal tumours. Patients with multifocal tumours were more likely to be at high genomic risk as compared to patients with unifocal tumours (22.7% versus 17.3%, odds ratio [OR] 1.45, 95% confidence interval [CI] 1.02-2.07, P = 0.038). We did not find a significant association between tumour focality and DMFS (97.1% for unifocal versus 96.9% for multifocal, hazard ratio [HR] = 1.55, 95% CI 0.68-3.46, P = 0.172), nor a signal for a potential interaction between the prognostic effect of the 70-GS and focality of the tumour regarding DMFS.

CONCLUSION

In the group of clinical low-risk MINDACT patients, multifocal tumours were more likely to have a high-risk 70-GS profile compared to unifocal tumours. We did not observe a significant interaction between multifocality and the 70-GS with respect to survival without distant metastasis in these patients.

Marking the axilla with radioactive iodine seeds (MARI procedure) may reduce the need for axillary dissection after neoadjuvant chemotherapy for breast cancer

Background

An important benefit of neoadjuvant chemotherapy is the increased potential for breast-conserving surgery. At present the response of axillary lymph node metastases to chemotherapy is not easily assessed, rendering axilla-conserving treatment difficult. The aim was to assess a new surgical method for evaluating the axillary response to chemotherapy.

Methods

Before neoadjuvant chemotherapy, proven tumour-positive axillary lymph nodes were localized using ultrasound-guided insertion of iodine-125-labelled (I-125) seeds. After neoadjuvant chemotherapy, the marked lymph nodes were removed selectively with the use of a γ probe. A complete axillary lymph node clearance was carried out to determine whether the pathological response in the marked node was indicative of that in the other lymph nodes.

Results

Tumour-positive axillary lymph nodes were localized successfully with I-125 seeds in 15 patients. The marked lymph node was detected and removed selectively after neoadjuvant chemotherapy in all patients. The pathological response to chemotherapy in the marked lymph node was indicative of the overall response in other removed lymph nodes.

Conclusion

This study showed that marking and selectively removing metastatic lymph nodes after neoadjuvant chemotherapy was feasible. The tumour response in the marked lymph node may be used to tailor further axillary treatment, making axilla-conserving surgery a possibility.

The relevance of breast cancer subtypes in the outcome of neoadjuvant chemotherapy

Background

Breast cancer is increasingly considered a heterogeneous disease. The aim of this study was to assess the differences between histological and receptor-based subtypes in breast-conserving surgery and pathological complete response (pCR) after neoadjuvant chemotherapy.

Method

A consecutive series of 254 patients with operable breast cancer treated with neoadjuvant chemotherapy was analyzed. Tumors were classified according to their receptor status in estrogen receptor (ER)-positive tumors (HER2-negative), triple-negative tumors, and HER2-positive tumors. The type of surgery feasible prior to neoadjuvant chemotherapy was compared with the actual surgery performed.

Results

The overall increase in breast-conserving surgery was 37% (73 of 198). In patients with ductal and lobular carcinomas this increase was 41% (63 of 152, 95% confidence interval [95% CI] 0.34–0.49) and 20% (7 of 35, 95% CI 0.10–0.36), respectively (P = 0.02). Half of the patients with lobular carcinoma had to undergo a secondary mastectomy because of incomplete resection margins. In ER-positive, triple-negative and HER2-positive tumors, the increase in breast-conserving surgery was 39% (42 of 109, 95% CI 0.30–0.48), 24% (11 of 45, 95% CI 0.14–0.38), and 45% (20 of 44, 95% CI 0.32–0.60) (P = 0.11). The pCR rate in ductal and lobular carcinomas was 12% (23 of 195) and 2% (1 of 42), respectively (P = 0.09). In ER-positive, triple-negative and HER2-positive tumors the pCR rates were 2% (3 of 138), 28% (16 of 57), and 18% (10 of 56), respectively. Multivariate analysis showed that the receptor-based subtype was the only significant predictor of pCR (P = 0.004).

Conclusion

In lobular tumors the benefit with regard to breast-conserving surgery of neoadjuvant chemotherapy is questionable. Although in ER-positive tumors the pCR rate is low, the increase in breast-conserving surgery was remarkable in ductal ER-positive tumors.

Technical aspects of the sentinel node biopsy in the EORTC AMAROS sentinel node trial

Abstract #1006

Background: The AMAROS trial is a phase III study comparing axillary lymph node dissection (ALND) with axillary radiation therapy (ART) in patients with proven axillary metastasis by sentinel node biopsy (SNB). The main objective of the trial is to prove equivalent locoregional control and reduced morbidity for ART. The aim of this interim analysis was to analyze the technical aspects of the SNB.
 Methods: The first 2000 patients with operable unifocal invasive breast cancer (5-30 mm) and clinically negative lymph nodes enrolled in the AMAROS trial between 2001 and 2005 were analyzed. The 26 participating institutions have been site visited as part of the surgical quality assurance. SNB is performed using preoperative lymphoscintigraphy, blue dye and a gamma-ray detection probe. Patients with a negative sentinel node were not subjected to ALND or ART.
 Results: The SN identification rate was 97% (range per institute 89%- 99%), 33% (n=658) of the patients were SNB positive, 62% (n=1245) were SNB negative and 2%(n=32) had other outcomes (non-axillary, missing data). Median two sentinel nodes were removed in the SNB positive as well as the SNB negative group. In 17% (344) of the patients, non-blue and non radio-active nodes were removed during the sentinel node procedure, median 1 node. In 11 patients, these nodes were the only tumor positive nodes found. In the SNB positive group the incidence of macro-, micrometastasis and isolated tumor cells was 61% (389), 26% (164) and 13% (80), respectively. In the ALND arm, further nodal involvement was seen 47,5% , 21,4 % and 16,7%, respectively. There was no correlation between the size of metastasis and the tumor size, grade or histological subtype. Of the sentinel nodes 59% (1907/3259) were radioactive and blue, 33% (1087/3259) were only radioactive, 8 %(265/3259) were only blue. Non-visualization on lymphoscintigraphy was seen in 7.6%(152), in 78%(118) of these cases a sentinel node was found during surgery. At least one sentinel node was located in the axilla in 89%(1777), in the internal mammary chain in 5% (104) and infra/supraclavicular in 1%(15). The injection site was intra/peritumoral in 53% subcutane/intradermal over the tumor in 9% periareolair in 16%, a combination in 4%, missing data 17%. Sentinel nodes in the internal mammary chain were significantly correlated with a intratumoral injection technique.
 Conclusions: These results indicate that with a 97% detection rate in this prospective international multicenter study using the combination of radioactive tracer and blue dye, the sentinel node procedure is highly effective. Differences in injection site affect the finding of non axillary sentinel nodes.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1006.

[Neoadjuvant systemic therapy in patients with operable primary breast cancer: more benefits than breast-conserving therapy]

OBJECTIVE

To analyse the extent to which primary systemic therapy (PST) achieves the main goals in patients with operable primary breast cancer, these goals being breast-conserving therapy and pathological complete remission (pCR), and to evaluate the response.

DESIGN

Retrospective.

METHOD

In a retrospective analysis of 254 patients treated with PST in 2000-2007 in the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, patients with inoperable disease (T4 and/or N3) were excluded. The response was mostly evaluated using contrast-enhanced MRI, whereby the chemotherapy regimen was switched if the reduction in the largest diameter of contrast washout was less than 25%. pCR was defined as no evidence of invasive cancer in the breast and axilla in the resection specimen.

RESULTS

In patients with ductal carcinoma and lobular carcinoma an increase in breast-conserving therapy was seen in 32% and 17% of patients respectively. The pCR rate was 12% and 2% respectively. Secondary mastectomy because of irradical resection was required in 3% and 50% respectively. Multivariate analysis indicated that molecular type, defined on the basis of the expression of hormone receptors and human epidermal growth factor receptor 2 (HER2), i.e. luminal (oestrogen receptor-positive), basal (hormone receptor-negative and HER2-negative) and HER2-positive tumours treated with trastuzumab was the only independent predictor of pCR; 2%, 28% and 35% respectively (p=0.004). In 43 patients the chemotherapy regimen was adjusted because the tumour did not respond sufficiently. A favourable clinical response was observed in 72% (31/43) of these patients.

CONCLUSION

The observed increase in the number of breast-conserving therapies after PST was clinically relevant. PST may be more effective when contrast-enhanced MRI is used for interim evaluation, based on which the treatment may be switched. There was a clear difference in histological and molecular types of tumour and therefore the choice of treatment may be adjusted accordingly.