Impact of BCL2 and p53 on postmastectomy radiotherapy response in high-risk breast cancer. A subgroup analysis of DBCG82 b&c

Bcl-2 expression and prognostic significance in feline invasive mammary carcinomas: a retrospective observational study

BACKGROUND

Cats spontaneously develop invasive mammary carcinomas with high clinical aggressiveness, and are considered relevant animal models for human breast cancer. Bcl-2 is an anti-apoptotic pro-survival protein, whose expression is associated with a favorable outcome in human breast cancer. The aim of our study was to determine the frequency of Bcl-2 expression in feline invasive mammary carcinomas (FMCs), its relationship with other clinicopathologic variables, and its prognostic value. This retrospective study included 180 FMCs, diagnosed in female cats treated by surgery only, with a 2-year follow-up post-mastectomy. Bcl-2, ER, PR, Ki-67, HER2, and CK5/6 expression were determined by automated immunohistochemistry. A receiver-operating-characteristic curve was used to set the threshold for Bcl-2 positivity.

RESULTS

The cohort comprises 32% (57/180) luminal FMCs defined by ER and/or PR positivity, and 68% (123/180) triple-negative FMCs (negative for ER, PR, and HER2). Bcl-2 expression was considered as positive when at least 65% of tumor cells were immunohistochemically stained. Thirty-one out of 180 FMCs (17%) were Bcl-2-positive. There was no significant association between Bcl-2 expression, and the tumor size, nodal stage, histological grade, or ER, PR, Ki-67, HER2, and CK5/6 expression. By multivariate survival analysis (Cox proportional-hazards regression), Bcl-2 positivity in FMCs was associated with longer disease-free interval (p = 0.005, HR = 0.38), overall survival (p = 0.028, HR = 0.61), and cancer-specific survival (p = 0.019, HR = 0.54) independently of other powerful prognostic factors such as pathologic tumor size, pathologic nodal stage, and distant metastasis. The positive prognostic value of Bcl-2 was confirmed in both luminal FMCs, of which 9/57 (16%) were Bcl-2-positive, and in basal-like triple-negative (ER-, PR-, HER2-, CK5/6+) FMCs, of which 14/76 (18%) were Bcl-2-positive.

CONCLUSIONS

Compared to human breast cancer, Bcl-2 positivity in feline invasive mammary carcinomas is also associated with better outcome, but is less common, and not associated with ER, PR, and HER2 expression. Cats with spontaneous Bcl-2-positive FMCs could be useful in preclinical trials evaluating anti-Bcl-2 strategies for chemoresistant luminal or triple-negative breast cancers.

Identification and validation of single-sample breast cancer radiosensitivity gene expression predictors

BACKGROUND

Adjuvant radiotherapy is the standard of care after breast-conserving surgery for primary breast cancer, despite a majority of patients being over- or under-treated. In contrast to adjuvant endocrine therapy and chemotherapy, no diagnostic tests are in clinical use that can stratify patients for adjuvant radiotherapy. This study presents the development and validation of a targeted gene expression assay to predict the risk of ipsilateral breast tumor recurrence and response to adjuvant radiotherapy after breast-conserving surgery in primary breast cancer.

METHODS

Fresh-frozen primary tumors from 336 patients radically (clear margins) operated on with breast-conserving surgery with or without radiotherapy were collected. Patients were split into a discovery cohort (N = 172) and a validation cohort (N = 164). Genes predicting ipsilateral breast tumor recurrence in an Illumina HT12 v4 whole transcriptome analysis were combined with genes identified in the literature (248 genes in total) to develop a targeted radiosensitivity assay on the Nanostring nCounter platform. Single-sample predictors for ipsilateral breast tumor recurrence based on a k-top scoring pairs algorithm were trained, stratified for estrogen receptor (ER) status and radiotherapy. Two previously published profiles, the radiosensitivity signature of Speers et al., and the 10-gene signature of Eschrich et al., were also included in the targeted panel.

RESULTS

Derived single-sample predictors were prognostic for ipsilateral breast tumor recurrence in radiotherapy-treated ER+ patients (AUC 0.67, p = 0.01), ER+ patients without radiotherapy (AUC = 0.89, p = 0.02), and radiotherapy-treated ER- patients (AUC = 0.78, p < 0.001). Among ER+ patients, radiotherapy had an excellent effect on tumors classified as radiosensitive (p < 0.001), while radiotherapy had no effect on tumors classified as radioresistant (p = 0.36) and there was a high risk of ipsilateral breast tumor recurrence (55% at 10 years). Our single-sample predictors developed in ER+ tumors and the radiosensitivity signature correlated with proliferation, while single-sample predictors developed in ER- tumors correlated with immune response. The 10-gene signature negatively correlated with both proliferation and immune response.

CONCLUSIONS

Our targeted single-sample predictors were prognostic for ipsilateral breast tumor recurrence and have the potential to stratify patients for adjuvant radiotherapy. The correlation of models with biology may explain the different performance in subgroups of breast cancer.

Adjuvant radiation therapy of regional lymph nodes in breast cancer - a meta-analysis of randomized trials- an update

BACKGROUND

Adjuvant radiotherapy (RT) of regional lymph nodes (LN) in early breast cancer is still a matter of debate. RT increases the Overall survival (OS) rate of breast cancer patients after breast conserving surgery and after mastectomy in patients with involved LN. The contribution of RT to regional LN to this improvement was poorly identified. Recently, the results of three large randomized trials addressing this question were published as full papers.

MATERIAL AND METHODS

Published data of the MA.20 (n = 1832), the EORTC22922-10925 (EORTC) (n = 4004) trial and the French trial (n = 1334) were the foundation of this meta-analysis. Major eligibility criteria were positive i) axillary LN (all trials), ii) LN negative disease with high risk for recurrence (MA.20), and iii) medial/central tumor location (French, EORTC). The MA.20 and the EORTC trial analyzed the effect of additional regional RT to the internal mammary (IM) LN and medial supraclavicular (MS) LN, whereas in the French trial all patients received RT to the MS-LN and solely RT to the IM-LN was randomized. Primary endpoint was OS. Secondary endpoints were disease-free survival (DFS) and distant metastasis free survival (DMFS).

RESULTS

Regional RT of MS-LN and IM-LN (MA.20 and EORTC) resulted in a significant improvement of OS [Hazard Ratio (HR) 0.88 (95 % CL 0.78 - 0.99)]. Adding results of the French trial and using a random effects model to respect the different design of the French trial, the effect on OS of regional RT remained significant [HR 0.90 (95 % CL 0.82 - 0.99)]. The absolute benefits in OS were 1 % in the MA.20 trial at 10 years, 1.6 % in the EORTC trial at 10 years, and 3.3 % in the French trial at 10 years (not significant in single trials). Regional RT of MS-LN and IM-LN (MA.20 and EORTC) yielded to a significant improvement of DFS [HR 0.86 (95 % CL 0.78 - 0.95)] and DMFS [HR 0.84 (95 % CL 0.75 - 0.94)].

CONCLUSION

Additional regional RT to the internal mammary and medial supraclavicular LN statistically significantly improved DFS, DMFS, and OS in stage I-III breast cancer.

DEGRO practical guidelines for radiotherapy of breast cancer IV: radiotherapy following mastectomy for invasive breast cancer

BACKGROUND AND PURPOSE

Since the last recommendations from the Breast Cancer Expert Panel of the German Society for Radiation Oncology (DEGRO) in 2008, evidence for the effectiveness of postmastectomy radiotherapy (PMRT) has grown. This growth is based on updates of the national S3 and international guidelines, as well as on new data and meta-analyses. New aspects were considered when updating the DEGRO recommendations.

METHODS

The authors performed a comprehensive survey of the literature. Data from recently published (meta-)analyses, randomized clinical trials and international cancer societies' guidelines yielding new aspects compared to 2008 were reviewed and discussed. New aspects were included in the current guidelines. Specific issues relating to particular PMRT constellations, such as the presence of risk factors (lymphovascular invasion, blood vessel invasion, positive lymph node ratio >20 %, resection margins <3 mm, G3 grading, young age/premenopausal status, extracapsular invasion, negative hormone receptor status, invasive lobular cancer, size >2 cm or a combination of ≥ 2 risk factors) and 1-3 positive lymph nodes are emphasized.

RESULTS

The evidence for improved overall survival and local control following PMRT for T4 tumors, positive resection margins, >3 positive lymph nodes and in T3 N0 patients with risk factors such as lymphovascular invasion, G3 grading, close margins, and young age has increased. Recently identified risk factors such as invasive lobular subtype and negative hormone receptor status were included. For patients with 1-3 positive lymph nodes, the recommendation for PMRT has reached the 1a level of evidence.

CONCLUSION

PMRT is mandatory in patients with T4 tumors and/or positive lymph nodes and/or positive resection margins. PMRT should be strongly considered in patients with T3 N0 tumors and risk factors, particularly when two or more risk factors are present.

Positive immunohistochemical expression of bcl-2 in hormone-independent breast carcinomas is associated with a greater lymph node involvement and poor outcome

To study the immunohistochemical expression of bcl-2 in patients with hormone-independent breast infiltrating ductal carcinomas (IDC) and its possible association with other clinico-biological parameters and outcome. Our study group included 72 females with hormone-independent (ER and PgR negative) infiltrating ductal breast carcinomas. Age, tumor size, axillary lymph node involvement (N), distant metastasis and histological grade, as well as the immunohistochemical expression of Ki67, p53 and androgen receptor (AR), were analyzed. We follow up 57 patients during a period of time ranged between 20 and 193 months (80.2 ± 58.3; median 78 months). Of all IDCs included in our study, 18 were ER-/PgR-/bcl-2+ and 54 ER-/PgR-/bcl-2-. The percentages of slightly bcl-2-positive (+) and bcl-2-strong positive (++) cases were 25 and 19 %, respectively, values lower than those observed in ER+/PgR+ tumors (79.3 and 86.8 %, respectively). Breast IDC with positivity (+) for bcl-2 showed, exclusively, greater lymph node involvement higher than 3 nodes (N+ >3) (p 0.021) and a great number of deaths due to the tumor (p 0.011). Same results were obtained when we compared bcl-2-negative and bcl-2-strong positive (++) subgroups. Our results led us to consider that the positive (+ or ++) immunohistochemical expression of bcl-2 in hormone-independent (ER and PgR negative) breast carcinomas is associated with greater axillary lymph node involvement and a greater number of deaths in the follow-up, being these data opposite to that observed in hormone-dependent tumors.

Bcl-2 expression and triple negative profile in breast carcinoma

Many biomarkers for breast cancer prognosis have been proposed during the last two decades, among which HER2 and oestrogen receptors are of common use in routine clinical practice. However, in recent years, BCL2 has been recognized as an important prognostic parameter in human breast cancer, although its clinical utility is well established. The aim of this study was to examine the protein expression patterns of BCL2, HER2, oestrogen (ER) and progesterone receptors (PR) and to evaluate their correlation with survival and other prognostic parameters such as tumour size, histological grade and metastasis. We used a retrospective study including 84 Tunisian women with breast cancer. Immunohistochemistry was used to measure protein expression levels of several biomarkers. Association with conventional biopathological factors was analysed by SPSS (version13). The expression rates of BCL2, HER2, ER and PR were, respectively, 69, 62, 58.3 and 51.2%. In univariate analyses, BCL2 was highly correlated with both PR (P < 0.001) and ER (P = 0.006) and also with HER2 expression (P = 0.001). The triple negative profile showed a significant association with SBR (P = 0.016) and BCL2 expression (P = 0.02). In multivariate analyses, a significant association was maintained between BCL2 and both PR and ER (P = 0.02 and P = 0.004, respectively). Survival analysis showed that BCL2 expression was positively correlated with patients survival (P = 0.032). A Bayesian network analysis of all the variables confirmed the high value of BCL2 expression as a predictor of survival. As conclusion, BCL2 expression seems to be a very useful factor that should be in combination with HER2 and ER in breast cancer prognosis.

Postoperative radiotherapy in DBCG during 30 years. Techniques, indications and clinical radiobiological experience

During the time period 1977-2007 postoperative radiotherapy in DBCG has varied considerably with regard to techniques and indications together with changes in the extent of surgery and adjuvant systemic therapy. The radiation treatment has been developed on the basis of clinical, radiophysical and radiobiological principles, encompassing also practical problems such as available equipment in the different centres and at times lack of sufficient machine capacity. The paper focus especially on the comprehensive work done prior to the DBCG 82 b&c studies, in order to optimize radiotherapy in all aspects prior to the evaluation of the efficacy of this treatment modality. The results from these trials did succeed in clear evidence that radiotherapy has an important role in the multidisciplinary treatment of early breast cancer. In parallel to these studies a new and challenging use of radiotherapy after breast conserving surgery was evaluated in the DBCG TM 82 protocol. The experience obtained with different techniques in this study formed the basis for the current principles of radiotherapy after lumpectomy. Reduction of radiation related morbidity has been a major issue for the DBCG radiotherapy group, and in this aspect several studies, including quality control visits, have been carried out to make the relevant modifications and to evaluate deviations from the guidelines between the centres. The background for the changes in radiotherapy is described for each of the programme periods as well as future perspectives which will include further refinements of the target and adjustments of dose and fractionation in selected patients.

A comparison between p53 accumulation determined by immunohistochemistry and TP53 mutations as prognostic variables in tumours from breast cancer patients

BACKGROUND

p53 accumulation and TP53 mutations are known prognostic markers for breast cancer. To clarify their interrelationship and the importance of different TP53 mutation types, these markers were investigated in tumours from 630 patients with breast cancer.

MATERIALS AND METHODS

Tumour sections were stained for p53 and scored based on staining intensity and percentages of invasive tumour cells with nuclear staining. TP53 mutations were identified by sequencing. Patient cohorts were from the DBCG (Danish Breast Cancer Cooperative Group) protocols DBCG82 and DBCG89.

RESULTS

TP53 was mutated in 29% of the patients. The disease-specific survival (DSS) at 15 years of follow-up for patients with missense mutations directly involved in DNA or zinc binding was 21+/-8%. Patients with the remaining missense mutations within the structural/conserved domains and patients with null mutations had a DSS of 36+/-6% and 31+/-17%, respectively. For patients without TP53 mutations and patients with mutations affecting amino acids outside these domains, the 15 year DSS was 51+/-3% and 71+/-10%, respectively. p53 accumulation was successfully scored in 567 patients and categorized into three groups. Tumours with no p53 expression had a high frequency of null mutations (37% compared to 10% in the whole cohort), and tumours with high p53 expression contained 82% of the missense mutations inside structural/conserved domains including those directly involved in DNA or zinc binding.

CONCLUSION

The clinical outcome for breast cancer patients is significantly different for different TP53 mutation types, but further functional studies are required to clarify the exact role of these mutation types. Most of the mutations that lead to mutant p53 protein accumulation can be detected by immunohistochemistry but the specificity is low. Samples showing lack of detectable p53 protein should be considered as an indication of a possible null mutation.