Marc A. Bollet

Ploidy and Large-Scale Genomic Instability Consistently Identify Basal-like Breast Carcinomas with BRCA1/2 Inactivation

BRCA1 inactivation is a frequent event in basal-like breast carcinomas (BLC). However, BRCA1 can be inactivated by multiple mechanisms and determining its status is not a trivial issue. As an alternate approach, we profiled 65 BLC cases using single-nucleotide polymorphism arrays to define a signature of BRCA1-associated genomic instability. Large-scale state transitions (LST), defined as chromosomal break between adjacent regions of at least 10 Mb, were found to be a robust indicator of BRCA1 status in this setting. Two major ploidy-specific cutoffs in LST distributions were sufficient to distinguish highly rearranged BLCs with 85% of proven BRCA1-inactivated cases from less rearranged BLCs devoid of proven BRCA1-inactivated cases. The genomic signature we defined was validated in a second independent series of 55 primary BLC cases and 17 BLC-derived tumor cell lines. High numbers of LSTs resembling BRCA1-inactivated BLC were observed in 4 primary BLC cases and 2 BLC cell lines that harbored BRCA2 mutations. Overall, the genomic signature we defined predicted BRCA1/2 inactivation in BLCs with 100% sensitivity and 90% specificity (97% accuracy). This assay may ease the challenge of selecting patients for genetic testing or recruitment to clinical trials of novel emerging therapies that target DNA repair deficiencies in cancer.

The Molecular Subtype Classification Is a Determinant of Sentinel Node Positivity in Early Breast Carcinoma

Introduction Several authors have underscored a strong relation between the molecular subtypes and the axillary status of breast cancer patients. The aim of our work was to decipher the interaction between this classification and the probability of a positive sentinel node biopsy. Materials and Methods Our dataset consisted of a total number of 2654 early-stage breast cancer patients. Patients treated at first by conservative breast surgery plus sentinel node biopsies were selected. A multivariate logistic regression model was trained and validated. Interaction covariate between ER and HER2 markers was a forced input of this model. The performance of the multivariate model in the training and the two validation sets was analyzed in terms of discrimination and calibration. Probability of axillary metastasis was detailed for each molecular subtype. Results The interaction covariate between ER and HER2 status was a stronger predictor (p = 0.0031) of positive sentinel node biopsy than the ER status by itself (p = 0.016). A multivariate model to determine the probability of sentinel node positivity was defined with the following variables; tumour size, lympho-vascular invasion, molecular subtypes and age at diagnosis. This model showed similar results in terms of discrimination (AUC = 0.72/0.73/0.72) and calibration (HL p = 0.28/0.05/0.11) in the training and validation sets. The interaction between molecular subtypes, tumour size and sentinel nodes status was approximated. Discussion We showed that biologically-driven analyses are able to build new models with higher performance in terms of breast cancer axillary status prediction. The molecular subtype classification strongly interacts with the axillary and distant metastasis process.

Breast-Conserving Treatment in the Elderly: Long-Term Results of Adjuvant Hypofractionated and Normofractionated Radiotherapy

PURPOSE To evaluate the long-term cause-specific survival (CSS), locoregional recurrence-free survival (LRFS), and metastases-free survival (MFS) in elderly breast cancer patients receiving adjuvant normofractionated (NF) or hypofractionated (HF) radiotherapy (RT). METHODS AND MATERIALS Between 1995 and 1999, 367 women aged >or=70 years with nonmetastatic Stage T1 or T2 tumors were treated by breast-conserving surgery and adjuvant RT at the Institut Curie. They underwent wide tumor excision with or without lymph node dissection followed by RT. They received either a NF-RT schedule, which delivered a total dose of 50 Gy (25 fractions, 5 fractions weekly) to the whole breast, followed by a boost to the tumor bed when indicated, or a HF-RT schedule, which delivered a total dose of 32.5 Gy (five fractions of 6.5 Gy, once weekly) with no subsequent boost. The HF-RT schedule was indicated for the more elderly patients. RESULTS A total of 317 patients were in the NF-RT group, with 50 in the HF-RT group. The median follow-up was 93 months (range, 9-140). The 5- and 7-year CSS, LRFS, and MFS rates were similar in both groups. The 5-year NF-RT and HF-RT rate was 96% and 95% for CSS, 95% and 94% for LRFS, and 94% and 95% for MFS, respectively. The 7-year NF-RT and HF-RT rate was 93% and 87% for CSS, 93% and 91% for LRFS, and 92% and 93% for MFS, respectively. CONCLUSION According to the findings from this retrospective study, the HF-RT schedule is an acceptable alternative to NF-RT for elderly patients. However, large-scale prospective randomized trials are needed to confirm these results.

Analysis of the copy number profiles of several tumor samples from the same patient reveals the successive steps in tumorigenesis

We present a computational method, TuMult, for reconstructing the sequence of copy number changes driving carcinogenesis, based on the analysis of several tumor samples from the same patient. We demonstrate the reliability of the method with simulated data, and describe applications to three different cancers, showing that TuMult is a valuable tool for the establishment of clonal relationships between tumor samples and the identification of chromosome aberrations occurring at crucial steps in cancer progression.

How to Boost the Breast Tumor Bed? A Multidisciplinary Approach in Eight Steps

PURPOSE To describe a new procedure for breast radiotherapy that will improve tumor bed localization and radiotherapy treatment using a multidisciplinary approach. PATIENTS AND METHODS This pilot study was conducted by departments of radiation oncology, surgery, and radiology. A new procedure has been implemented, summarized as eight steps: from pre-surgery contrast CT to surgery, tumor bed planning target volume (PTV) determination, and finally breast and tumor bed irradiation. RESULTS Twenty patients presenting with T1N0M0 tumors were enrolled in the study. All patients underwent lumpectomy with the placement of surgical clips in the tumor bed region. During surgery, 1 to 5 clips were placed in the lumpectomy cavity before the plastic procedure. All patients underwent pre- and postoperative CT scans in the treatment position. The two sets of images were registered with a match-point registration. All volumes were contoured and the results evaluated. The PTV included the clips region, the gross tumor volume, and the surgical scar, with an overall margin of 5-10 mm in all directions, corresponding to localization and setup uncertainties. For each patient the boost PTV was discussed and compared with our standard forward-planned PTV. CONCLUSIONS We demonstrate the feasibility of a tumor bed localization and treatment procedure that seems adaptable to routine practice. Our study shows the advantages of a multidisciplinary approach for tumor bed localization and treatment. The use of more than 1 clip associated with pre- to postoperative CT image registration allows better definition of the PTV boost volume.

Preliminary Results of Whole Brain Radiotherapy With Concurrent Trastuzumab for Treatment of Brain Metastases in Breast Cancer Patients

PURPOSE To assess the use of trastuzumab concurrently with whole brain radiotherapy (WBRT) for patients with brain metastases from human epidermal growth factor receptor-2-positive breast cancer. METHODS AND MATERIALS Between April 2001 and April 2007, 31 patients with brain metastases from human epidermal growth factor receptor-2-positive breast cancer were referred for WBRT with concurrent trastuzumab. At brain progression, the median age was 55 years (range, 38-73), and all patients had a performance status of 0-2. The patients received trastuzumab 2 mg/kg weekly (n = 17) or 6 mg/kg repeated every 21 days (n = 14). In 26 patients, concurrent WBRT delivered 30 Gy in 10 daily fractions. In 6 patients, other fractionations were chosen because of either poor performance status or patient convenience. RESULTS After WBRT, radiologic responses were observed in 23 patients (74.2%), including 6 (19.4%) with a complete radiologic response and 17 (54.8%) with a partial radiologic response. Clinical responses were observed in 27 patients (87.1%). The median survival time from the start of WBRT was 18 months (range, 2-65). The median interval to brain progression was 10.5 months (range, 2-27). No Grade 2 or greater acute toxicity was observed. CONCLUSION The low toxicity of trastuzumab concurrently with WBRT should probably not justify delays. Although promising, these preliminary data warrant additional validation of trastuzumab as a potential radiosensitizer for WBRT in brain metastases from breast cancer in the setting of a clinical trial.

Targeting poly(ADP-ribose) polymerase activity for cancer therapy

Poly(ADP-ribosyl)ation is a ubiquitous protein modification found in mammalian cells that modulates many cellular responses, including DNA repair. The poly(ADP-ribose) polymerase (PARP) family catalyze the formation and addition onto proteins of negatively charged ADP-ribose polymers synthesized from NAD+. The absence of PARP-1 and PARP-2, both of which are activated by DNA damage, results in hypersensitivity to ionizing radiation and alkylating agents. PARP inhibitors that compete with NAD+ at the enzyme’s activity site are effective chemo- and radiopotentiation agents and, in BRCA-deficient tumors, can be used as single-agent therapies acting through the principle of synthetic lethality. Through extensive drug-development programs, third-generation inhibitors have now entered clinical trials and are showing great promise. However, both PARP-1 and PARP-2 are not only involved in DNA repair but also in transcription regulation, chromatin modification, and cellular homeostasis. The impact on these processes of PARP inhibition on long-term therapeutic responses needs to be investigated.

Radiotherapy for Stage II and Stage III Breast Cancer Patients With Negative Lymph Nodes After Preoperative Chemotherapy and Mastectomy

PURPOSE To evaluate the effect of postmastectomy radiotherapy (PMRT) in Stage II-III breast cancer patients with negative lymph nodes (pN0) after neoadjuvant chemotherapy (NAC). PATIENTS AND MATERIALS Of 1,054 breast cancer patients treated with NAC at our institution between 1990 and 2004, 134 had pN0 status after NAC and mastectomy. The demographic data, tumor characteristics, metastatic sites, and treatments were prospectively recorded. The effect of PMRT on locoregional recurrence-free survival and overall survival (OS) was evaluated by multivariate analysis, including known prognostic factors. RESULTS Of the 134 eligible patients, 78 (58.2%) received PMRT and 56 (41.8%) did not. At a median follow-up time of 91.4 months, the 5-year locoregional recurrence-free survival and OS rate was 96.2% and 88.3% with PMRT and 92.5% and 94.3% without PMRT, respectively (p = NS). The corresponding values at 10 years were 96.2% and 77.2% with PMRT and 86.8% and 87.7% without PMRT (p = NS). On multivariate analysis, PMRT had no effect on either locoregional recurrence-free survival (hazard ratio, 0.37; 95% confidence interval, 0.09-1.61; p = .18) or OS (hazard ratio, 2.06; 95% confidence interval, 0.71-6; p = .18). This remained true in the subgroups of patients with clinical Stage II or Stage III disease at diagnosis. A trend was seen toward poorer OS among patients who had not had a pathologic complete in-breast tumor response after NAC (hazard ratio, 6.65; 95% confidence interval, 0.82-54.12; p = .076). CONCLUSIONS The results from the present retrospective study showed no increase in the risk of distant metastasis, locoregional recurrence, or death when PMRT was omitted in breast cancer patients with pN0 status after NAC and mastectomy. Whether the omission of PMRT is acceptable for these patients should be addressed prospectively.

Anatomical, clinical and radiological delineation of target volumes in breast cancer radiotherapy planning: individual variability, questions and answers

The purpose of the study was to evaluate the individual variability of anatomical and radiological delineation for breast cancer radiotherapy (RT) in preparation for new techniques and to propose practical solutions to improve delineation in everyday practice. In the first phase, a patient with stage T3N3M0 breast cancer and complete response after neoadjuvant chemotherapy was assessed by CT scan in the treatment position before RT. 11 radiation oncologists (5 breast cancer specialists and 6 residents) independently delineated the breast and lymph node (LN) regions before definition of target volumes. Organs at risk (heart, lung, thyroid and brachial plexus) were also delineated. All regions (breast, axilla, supraclavicular LN, infraclavicular LN and internal mammary chain) were delineated and compared in terms of volume. Comparative analysis was performed with Aquilab software. Differences in the clinical and radiological assessment were observed between the various radiation oncologists. Simplified rules of delineation were developed in the department. Using these rules, the second patients CT was delineated by the same physicians and better results were observed. Simplified rules of delineation were developed. In conclusion, major differences in anatomical and radiological delineation for breast cancer RT were observed among the physicians. This study led to the development of written delineation protocols. The study is ongoing with evaluation of the dosimetric impact and definition of different target volumes.

IMPROVING THE DEFINITION OF TUMOR BED BOOST WITH THE USE OF SURGICAL CLIPS AND IMAGE REGISTRATION IN BREAST CANCER PATIENTS

PURPOSE To evaluate the accuracy of a boost technique. METHODS AND MATERIALS Twenty-two patients underwent tumorectomy with placement of two or more clips in the surgical cavity before breast remodeling. Preoperative and postoperative computed tomography scans, with match-point registration, were performed on all patients. The relationship between the location of the gross tumor volume (GTV), defined on the preoperative scan, and clip clinical target volume (CTV) (clips with a 5-mm margin on the postoperative scan) was then studied, by use of commercial volume analysis software. RESULTS Of the patients, 4 had two clips, 2 had three clips, 8 had four clips, and 8 had five clips. The median GTV was 1.06 mL (range, 0.2-5.3 mL); clip CTV ranged from 2.4 to 21.5 mL. Volumetric analysis showed that in 7 cases (32%), there was no intersection between the GTV and the clip CTV, with the following distribution: 4 patients with two clips, 1 patient with three clips, 1 patient with four clips, and 1 patient with five clips. The common contoured volume was defined as the percent ratio between the intersection of the GTV and clip CTV and the GTV. It was found to be significantly increased if three or more clips were used vs. only two clips (common contoured volume, 35.45% vs. 0.73%; p = 0.028). Finally, the GTV and clip CTV volume relationship can be presented as follows: 12.5% to 33% overlap in 8 patients (36.4%), 50% to 75% in 5 patients (22.7%), and greater than 90% in 2 patients (9%). CONCLUSIONS The use of three or more clips during tumorectomy increases the accuracy of tumor bed delineation.