Breast Cancer Index and prediction of benefit from extended endocrine therapy in breast cancer patients treated in the Adjuvant Tamoxifen-To Offer More? (aTTom) trial

BACKGROUND

Extending the duration of adjuvant endocrine therapy reduces the risk of recurrence in a subset of women with early-stage hormone receptor-positive (HR+) breast cancer. Validated predictive biomarkers of endocrine response could significantly improve patient selection for extended therapy. Breast cancer index (BCI) [HOXB13/IL17BR ratio (H/I)] was evaluated for its ability to predict benefit from extended endocrine therapy in patients previously randomized in the Adjuvant Tamoxifen-To Offer More? (aTTom) trial.

PATIENTS AND METHODS

Trans-aTTom is a multi-institutional, prospective-retrospective study in patients with available formalin-fixed paraffin-embedded primary tumor blocks. BCI testing and central determination of estrogen receptor (ER) and progesterone receptor (PR) status by immunohistochemistry were carried out blinded to clinical outcome. Survival endpoints were evaluated using Kaplan-Meier analysis and Cox regression with recurrence-free interval (RFI) as the primary endpoint. Interaction between extended endocrine therapy and BCI (H/I) was assessed using the likelihood ratio test.

RESULTS

Of 583 HR+, N+ patients analyzed, 49% classified as BCI (H/I)-High derived a significant benefit from 10 versus 5 years of tamoxifen treatment [hazard ratio (HR): 0.35; 95% confidence interval (CI) 0.15-0.86; 10.2% absolute risk reduction based on RFI, P = 0.027]. BCI (H/I)-low patients showed no significant benefit from extended endocrine therapy (HR: 1.07; 95% CI 0.69-1.65; -0.2% absolute risk reduction; P = 0.768). Continuous BCI (H/I) levels predicted the magnitude of benefit from extended tamoxifen, whereas centralized ER and PR did not. Interaction between extended tamoxifen treatment and BCI (H/I) was statistically significant (P = 0.012), adjusting for clinicopathological factors.

CONCLUSION

BCI by high H/I expression was predictive of endocrine response and identified a subset of HR+, N+ patients with significant benefit from 10 versus 5 years of tamoxifen therapy. These data provide further validation, consistent with previous MA.17 data, establishing level 1B evidence for BCI as a predictive biomarker of benefit from extended endocrine therapy.

TRIAL REGISTRATION

ISRCTN17222211; NCT00003678.

Abstract P1-15-03: Management and outcomes of metaplastic breast cancer

Purpose/Objectives: Metaplastic breast cancer (MBC) is a rare malignancy composed of both epithelial and mesenchymal components that accounts for less than 1% of primary breast carcinomas. Knowledge of effective management of the disease remains limited. We retrospectively evaluated the treatment and outcomes of patients with MBC from three academic hospitals.

Materials/Methods: Patients diagnosed with MBC between June 2, 1993 and May 6, 2016 were identified. Demographic and clinical variables were extracted via primary chart review. Descriptive statistics were utilized to summarize the patient cohort's clinical course. The Kaplan-Meier method was used to obtain estimates of local control (LC) and survival.

Results: Seventy-six patients were identified with a median follow-up of 7.6 years (range: 0.18-19.9 years). The median age at diagnosis was 54 (range 28-81). About two-thirds of patients (67%, n=51) presented with a palpable mass while the remaining patients were screen-detected via mammogram (32%, n=24). The majority of patients were AJCC-7 stage I (38%, n=29) or stage II (49%, n=37), while 10% (n=8) were stage III and 3% (n= 2) stage IV. About half of tumors (46%, n=35) were subtyped using WHO histologic classification of MBC. Over half of subtyped cases were spindle cell carcinoma (51%, n=18), 17% were matrix-producing carcinoma (n=6), 23% were adenocarcinoma with squamous differentiation (n=8), 6% were carcinosarcoma (n=2), and 3% were mixed (n=1).The majority of patients had triple negative disease (82%, n=62), while 13% (n=10) had HR+/HER2- disease, and 5% (n=4) had HER2+ disease. Most patients had high grade tumors (84%, n=64) and received breast conserving surgery (61%, n=46) while 39% (n=29) had mastectomies. Seventy-six percent (n=58) of patients received chemotherapy and 61% (n=46) received radiation therapy. All HR+ patients received adjuvant endocrine therapy, and 1 patient received immunotherapy. Of patients who received chemotherapy, 78% (n=45) received adjuvant therapy alone, 17% (n=10) neoadjuvant therapy alone, and 5% (n=3) both. Seventy percent (n=41) of chemotherapy regimens included a taxane. Among 74 patients without metastatic disease at presentation, recurrences were observed in 18% (n=13). Most patients recurred distantly (69%, n=9), while the remainder had isolated local recurrences (n=4). Of 9 distant failures, 3 had MBC subtype information and all 3 were spindle cell carcinoma. Of 4 local recurrences, 3 of 4 were adenocarcinoma with squamous cell differentiation and 1 was spindle cell carcinoma. At a median follow-up of 7.6 years, the local recurrence-free survival was 88%, disease-free survival was 80%, and overall survival was 80%. Kaplan-Meier point estimates for remaining free of local recurrence versus distant recurrence were 99% (95% C.I., 90- 100) versus 96% (95% C.I., 87- 99) at 2 years and 88% (95% C.I., 76-94) versus 87% (95% C.I., 75- 93) at 5 years.

Conclusions: MBC is a rare histologic subtype that commonly presents with high-grade disease and triple-negative receptor status. In contrast to other smaller series, local and distant failure rates in this cohort were consistent with non-MBC triple negative cohorts. Additional molecular based research is warranted to further characterize features associated with local and distant failure.

Citation Format: Thomas H, Horick N, Spring LM, Brachtel EF, Jimenez RB. Management and outcomes of metaplastic breast cancer [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 P1-15-03.

Abstract P4-01-05: In vivo, intraoperative margin detection utilizing the Lumicell margin assessment system

This abstract was withdrawn by the authors.

Abstract P5-03-01: An optimized 92-gene assay for the molecular diagnosis of triple-negative breast cancer

Background: Triple negative breast cancer (TNBC) often presents as high grade, poorly differentiated tumors resulting in a more aggressive disease for which accurate and timely diagnosis is critical to treatment selection or clinical trial enrollment. Furthermore, the high rate of distant metastases and absence of breast-specific immunohistochemical markers that contribute to diagnostic uncertainty may delay or limit treatment modalities that can lead to poorer outcomes. The 92-gene assay is an RT-PCR-based cancer classifier that previously demonstrated 80% accuracy for the diagnosis of breast cancer. In this study, blinded validation of an optimized algorithm and assay specifically developed to improve performance in TNBC is described.

Methods: To increase clinical scope for the diagnosis of TNBC, formalin fixed paraffin embedded specimens (N=103) representing a range of breast tumor histologies (e.g. TNBC, adenoid cystic, neuroendocrine, metaplastic, lobular, mucinous, DCIS) were added to the tumor reference database. A revised computational algorithm was constructed by the integration of machine learning techniques. For validation, tumor specimens (N=160) of TNBC (57%) and non-breast tumors (43%) were blindly tested using a 92-gene cancer classifier (CancerTYPE ID®, Biotheranostics, Inc). Tumor type predictions were reported as rank-order probabilities based on the degree of similarity to the tumor reference database. Assay sensitivity based on concordance of the main tumor type prediction with the reference diagnosis established by clinicopathologic review was analyzed.

Results: Assay results included 85 breast carcinomas (TNBC) (53%), 23 Salivary gland carcinomas (14%), and 52 carcinomas (33%) representing 11 other tumor types. For performance in TNBC, the 92-gene assay demonstrated an overall sensitivity of 93% (CI, 86-98), and sensitivities of 96% [95% CI, 89-99] and 80% [95% CI, 52-96], in primary and metastatic tumors, respectively (P=0.085). Additional performance characteristics are shown in Table 1.

Table 1Pathology subsetN, Validation setN, Correct 92-gene assay predictionsSensitivity (95% CI)All TNBC91850.93 (0.86-0.98)TNBC-primary76730.96 (0.89-0.99)TNBC-metastatic15120.80 (0.52-0.96)All Non-breast69550.80 (0.68-0.88)Salivary gland carcinoma25230.92 (0.74-0.99)Overall performance1601400.88 (0.81-0.92)

Conclusions: An optimized 92-gene assay specifically modified to increase performance for the molecular diagnosis of TNBC showed strong accuracy in this blinded study. These findings support use of the 92-gene cancer classifier to aid in the diagnosis of primary or metastatic TNBC. With more refined tumor characterization, TNBC-specific chemotherapy regimens or clinical trial therapies may be pursued with the potential for improved patient outcomes.

Citation Format: Sullivan PS, Soifer HS, Liu J, Zhang Y, Schnabel CA, Brachtel EF. An optimized 92-gene assay for the molecular diagnosis of triple-negative breast cancer [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 P5-03-01.

P4-11-12: Molecular Phenotype of Breast Cancers in a Large Cohort of Young Women According to Time Interval Since Pregnancy

Background: The increase in breast cancer risk during pregnancy and post partum is well recognized. The cross-over to protective effect does not occur until many years later and varies with age at first birth. Recently, a genomic signature specific to the pregnant compared with the non-pregnant breast has been identified; this signature remains present in the postmenopausal parous breast. Given this, we investigated whether time interval since pregnancy affects the phenotype of breast cancers arising in young women compared with nulliparous women. Methods: We examined molecular phenotype, according to histologic grade and biomarker status, in relation to time since pregnancy in an ongoing prospective cohort study (n=355) of young women (≤40yrs) with breast cancer. Medical records were reviewed for tumor stage and receptor status. Parity was ascertained from questionnaires completed within 9 months of diagnosis. Tumor grade was determined by central pathology review. Using tumor grade and biomarker expression, cancers were categorized as luminal A (ER+ and/or PR+, HER2−, histologic grade 1 or 2); luminal B ( ER+ and/or PR+, HER2+, or ER and/or PR+, HER2− and grade 3); HER2 type (ER-, PR-, HER2+); and triple negative (ER-, PR-, HER2−).

Results: The median age of the study population is 37 years (range 17–40). Overall, 80% of women had stage 1 or 2 disease; 67% of cancers were ER positive and 32% showed HER2 overexpression. The distribution of breast cancer molecular phenotypes by time interval since last pregnancy is shown in the table.

Distribution of molecular phenotype by interval between last pregnancy and diagnosis

Pathologic features and molecular phenotype by patient age in a large cohort of young women with breast cancer

Prior studies have suggested a higher prevalence of high grade, ER-negative, HER2-positive, and basal-like carcinomas in young women with breast cancer. However, the precise distribution of poor prognostic features in this population remains unclear. We examined the pathologic features and distribution of molecular phenotype in relation to patient age in a large group of young women (≤40 years) with invasive breast cancer. Medical records were reviewed for clinical characteristics, tumor stage, and receptor status. Pathologic features, including those features associated with basal-like carcinomas, were examined by central review. Using tumor grade and biomarker expression, cancers were categorized as luminal A (ER+ and/or PR+ and HER2-, histologic grade 1 or 2); luminal B (ER+ and/or PR+ and HER2+, or ER and/or PR+, HER2- and grade 3); HER2 (ER and PR- and HER2+); and triple negative (ER-, PR-, and HER2-). Among 399 women of ≤40 years, 33% had luminal A tumors, 35% luminal B, 11% HER2 (ER-negative), and 21% triple negative. Compared to published results for all breast cancers, a greater proportion of young women had luminal B tumors, and a lesser proportion had luminal A. There were no significant differences in molecular phenotype, tumor stage or grade among the different age groups of young women. However, this population of young women presented with a different distribution of molecular phenotypes compared to the general population of women with breast cancer. These findings may have implications with regard to the etiology and prognosis of breast cancer in young women.

Development and validation of a model predictive of occult nipple involvement in women undergoing mastectomy

Background

This prospective study aimed to build a predictive model using preoperative information to aid selection for nipple-sparing mastectomy.

Methods

Two hundred consecutive skin-sparing mastectomy specimens without overt nipple involvement were evaluated. Demographic, preoperative pathology and imaging information was collected. Nipple specimens (2 × 2 × 2 cm) were sectioned at 3-mm intervals. Haematoxylin and eosin-stained slides were examined by a breast pathologist for involvement by tumour. Logistic regression analyses of 65 therapeutic procedures identified factors associated with occult involvement and created a predictive model. This was tested on specimens from a further 65 therapeutic procedures.

Results

Occult nipple involvement was noted in 32 (24·6 per cent) of 130 mastectomy specimens. In the training set, imaging diameter of the lesion and its distance from the nipple predicted nipple involvement on univariable analysis (P = 0·011 and P = 0·014 respectively). The multivariable logistic regression model was validated in the test set. The areas under the receiver–operating characteristic curve were 0·824 and 0·709 for the training and test sets respectively.

Conclusion

Three-quarters of women undergoing mastectomy did not have occult nipple involvement. A clinical tool including tumour size and distance from the nipple has been developed to improve patient selection for nipple-sparing mastectomy.

High frequency of β-catenin mutations in borderline endometrioid tumours of the ovary

Some low-grade endometrioid carcinomas arise from a background of endometrioid tumours of borderline malignancy. To determine the molecular mechanisms involved in the initiation of endometrioid carcinoma, the present study investigated whether the genetic alterations reported in these tumours (mutations in PTEN, KRAS, and beta-catenin genes, and microsatellite instability) are already present in endometrioid tumours of borderline malignancy. Eight endometrioid tumours of borderline malignancy were studied. By immunohistochemistry, beta-catenin was expressed in the nuclei of all tumours, suggesting the presence of stabilizing beta-catenin mutations. By mutational analysis, five different beta-catenin mutations were found in seven of eight cases (90%), affecting codons 32, 33, and 37. In contrast, only one tumour harboured a PTEN mutation, which affected codon 130. Neither KRAS mutations nor microsatellite instability was detected. A review of the literature indicated that beta-catenin mutations are characteristic of well-differentiated endometrioid carcinomas, since they were present in nearly 60% of grade I but in less of 3% of grade III tumours. In conclusion, the present study identifies beta-catenin mutation as a nearly constant molecular alteration in borderline endometrioid tumours, whereas PTEN and KRAS mutations and microsatellite instability are very infrequent. The findings in the present study, and previously reported data, strongly suggest that beta-catenin mutation is an early event in endometrioid ovarian carcinogenesis, and that it is involved in the development of low-grade endometrioid tumours.

Differences in the germinal centres of palatine tonsils and lymph nodes

The germinal centres of human palatine tonsils typically have four clearly recognizable compartments. The dark zone is identified by the presence of centroblasts and a thin follicular dendritic cell (FDC) network. The dense FDC network is divided into a CD23(low/-) portion adjacent to the dark zone (the basal light zone) and a CD23(high) portion, the apical light zone). The outer zone, which lies between the apical light zone and the follicular mantle, has only fine CD23- FDC processes. While these compartments were seen in 48 follicles from eight tonsils, the compartmental structure of 54 germinal centres in lymph nodes from 11 individuals was markedly different. The CD23+ FDC network in lymph node follicles extended into part of the dark zone and the inner part of the follicular mantle, and consequently no outer zone or basal light zone was identified. In both the lymph nodes and tonsils most T cells were CD4+ and located outside the dark zone; the concentration of these cells at the edge of germinal centres was typical of tonsil centres but was noted only occasionally in lymph nodes. The substantial minority of T cells that were CD4,CD57+ were located mainly in the dense FDC network.