Sequencing of breast cancer stem cell populations indicates a dynamic conversion between differentiation states in vivo

Peer reviewe

Risk of primary lung cancer after adjuvant radiotherapy in breast cancer-a large population-based study

Adjuvant radiotherapy (RT) for breast cancer (BC) has been associated with an increased risk of later radiation-induced lung cancer (LC). We examined the risk of primary LC in a population-based cohort of 52300 women treated for BC during 1992 to 2012, and 253796 age-matched women without BC. Cumulative incidence of LC was calculated by the Kaplan-Meier method, and the risk of LC after BC treatment was estimated by Cox proportional hazards regression analyses. Women with BC receiving RT had a higher cumulative incidence of LC compared to women with BC not receiving RT and women without BC. This became apparent 5 years after RT and increased with longer follow-up. Women with BC receiving RT had a Hazard ratio of 1.59 (95% confidence interval 1.37-1.84) for LC compared to women without BC. RT techniques that lower the incidental lung doses, e.g breathing adaption techniques, may lower this risk.Peer reviewe

Risk of ischemic heart disease after radiotherapy for ductal carcinoma in situ

The use of adjuvant radiotherapy (RT) in the management of ductal carcinoma in situ (DCIS) is increasing. Left-sided breast irradiation may involve exposure of the heart to ionising radiation, increasing the risk of ischemic heart disease (IHD). We examined the incidence of IHD in a population-based cohort of women with DCIS. The Breast Cancer DataBase Sweden (BCBase) cohort includes women registered with invasive and in situ breast cancers 1992-2012 and age-matched women without a history of breast cancer. In this analysis, 6270 women with DCIS and a comparison cohort of 31,257 women were included. Through linkage with population-based registers, data on comorbidity, socioeconomic status and incidence of IHD was obtained. Hazard ratios (HR) for IHD with 95% confidence intervals (CI) were analysed. Median follow-up time was 8.8 years. The risk of IHD was not increased for women with DCIS versus women in the comparison cohort (HR 0.93; 95% CI 0.82-1.06), after treatment with radiotherapy versus surgery alone (HR 0.77; 95% CI 0.60-0.98) or when analysing RT by laterality (HR 0.85; 95% CI 0.53-1.37 for left-sided versus right-sided RT). The risk of IHD was lower for women with DCIS allocated to RT compared to non-irradiated women and to the comparison cohort, probably due to patient selection. Comparison of RT by laterality did not show any over-risk for irradiation of the left breast.Peer reviewe

Sequencing-based breast cancer diagnostics as an alternative to routine biomarkers

Sequencing-based breast cancer diagnostics have the potential to replace routine biomarkers and provide molecular characterization that enable personalized precision medicine. Here we investigate the concordance between sequencing-based and routine diagnostic biomarkers and to what extent tumor sequencing contributes clinically actionable information. We applied DNA- and RNA-sequencing to characterize tumors from 307 breast cancer patients with replication in up to 739 patients. We developed models to predict status of routine biomarkers (ER, HER2,Ki-67, histological grade) from sequencing data. Non-routine biomarkers, including mutations in BRCA1, BRCA2 and ERBB2(HER2), and additional clinically actionable somatic alterations were also investigated. Concordance with routine diagnostic biomarkers was high for ER status (AUC = 0.95;AUC(replication) = 0.97) and HER2 status (AUC = 0.97;AUC(replication) = 0.92). The transcriptomic grade model enabled classification of histological grade 1 and histological grade 3 tumors with high accuracy (AUC = 0.98;AUC(replication) = 0.94). Clinically actionable mutations in BRCA1, BRCA2 and ERBB2(HER2) were detected in 5.5% of patients, while 53% had genomic alterations matching ongoing or concluded breast cancer studies. Sequencing-based molecular profiling can be applied as an alternative to histopathology to determine ER and HER2 status, in addition to providing improved tumor grading and clinically actionable mutations and molecular subtypes. Our results suggest that sequencing-based breast cancer diagnostics in a near future can replace routine biomarkersNonePublishe

Proteogenomics decodes the evolution of human ipsilateral breast cancer

Ipsilateral breast tumor recurrence (IBTR) is a clinically important event, where an isolated in-breast recurrence is a potentially curable event but associated with an increased risk of distant metastasis and breast cancer death. It remains unclear if IBTRs are associated with molecular changes that can be explored as a resource for precision medicine strategies. Here, we employed proteogenomics to analyze a cohort of 27 primary breast cancers and their matched IBTRs to define proteogenomic determinants of molecular tumor evolution. Our analyses revealed a relationship between hormonal receptors status and proliferation levels resulting in the gain of somatic mutations and copy number. This in turn re-programmed the transcriptome and proteome towards a highly replicating and genomically unstable IBTRs, possibly enhanced by APOBEC3B. In order to investigate the origins of IBTRs, a second analysis that included primaries with no recurrence pinpointed proliferation and immune infiltration as predictive of IBTR. In conclusion, our study shows that breast tumors evolve into different IBTRs depending on hormonal status and proliferation and that immune cell infiltration and Ki-67 are significantly elevated in primary tumors that develop IBTR. These results can serve as a starting point to explore markers to predict IBTR formation and stratify patients for adjuvant therapy

Gene expression profiling in primary breast cancer distinguishes patients developing local recurrence after breast-conservation surgery, with or without postoperative radiotherapy

Introduction Some patients with breast cancer develop local recurrence after breast-conservation surgery despite postoperative radiotherapy, whereas others remain free of local recurrence even in the absence of radiotherapy. As clinical parameters are insufficient for identifying these two groups of patients, we investigated whether gene expression profiling would add further information. Methods We performed gene expression analysis (oligonucleotide arrays, 26,824 reporters) on 143 patients with lymph node-negative disease and tumor-free margins. A support vector machine was employed to build classifiers using leave-one-out cross-validation. Results Within the estrogen receptor-positive (ER+) subgroup, the gene expression profile clearly distinguished patients with local recurrence after radiotherapy (n = 20) from those without local recurrence (n = 80 with or without radiotherapy). The receiver operating characteristic (ROC) area was 0.91, and 5,237 of 26,824 reporters had a P value of less than 0.001 (false discovery rate = 0.005). This gene expression profile provides substantially added value to conventional clinical markers (for example, age, histological grade, and tumor size) in predicting local recurrence despite radiotherapy. Within the ER- subgroup, a weaker, but still significant, signal was found (ROC area = 0.74). The ROC area for distinguishing patients who develop local recurrence from those who remain local recurrence-free in the absence of radiotherapy was 0.66 (combined ER+/ER-). Conclusion A highly distinct gene expression profile for patients developing local recurrence after breast-conservation surgery despite radiotherapy has been identified. If verified in further studies, this profile might be a most important tool in the decision making for surgery and adjuvant therapy

Breast Cancer in Young Women: Poor Survival Despite Intensive Treatment

The general aim of the thesis was to gain increased insight into the long-term prognosis for young women with breast cancer. In a population-based cohort of 22,017 women with breast cancer, we studied prognosis by age. Women aged <35 (n=471), 35–39 (n=858) and 40–49 (n=4789) were compared with women aged 50–69. The cumulative 5-year relative survival ratio (RSR) and the relative excess risk (RER) of mortality were calculated. Women <35 years of age had a worse survival than middle-aged women, partly explained by a later stage at diagnosis. After correction for stage, tumor characteristics and treatment, young age remained an independent risk factor for death. The excess risk of death in young women was only present in stage I-II disease and was most pronounced in women with small tumors. For in-depth studies on a large subpopulation from the original cohort (all 471 women aged <35 and a random sample of 700 women aged 35–69), we collected detailed data from the medical records, re-evaluated slides and produced TMAs from tumor tissue. Breast cancer- specific survival (BCSS), distant disease-free survival (DDFS) and locoregional recurrence- free survival (LRFS) by age were analysed. In a multivariate analysis, age <35 and age 35– 39 years conferred a risk in LRFS but not in DDFS and BCSS. The age-related differences in prognosis were most pronounced in early stage luminal Her2-negative tumors, where low age was an independent prognostic factor also for DDFS (HR 1.87 (1.03–3.44)). To study the importance of proliferation markers for the long-term prognosis in young women, protein expression of Ki-67, cyclin A2, B1, D1 and E1 was analysed in 504 women aged <40 and in 383 women aged ≥40. The higher expression of proliferation markers in young women did not have a strong impact on the prognosis. Proliferation markers are less important in young women, and Ki-67 was prognostic only in young women with Luminal PR+ tumors. Age <40 years was an independent risk factor of DDFS exclusively in this subgroup (adjusted HR 2.35 (1.22-4.50)). The only cyclin adding prognostic value beyond subtype in young women was cyclin E1. In a cohort of 469 women aged <40 and 360 women aged ≥40 we examined whether Her2 status assessed by silver enhanced in situ hybridization (SISH) for all cases, would reveal a proportion of women undiagnosed by routine Her2 testing and whether this would affect their prognosis. With SISH testing for all women, the Her2-positive rate increased from 20.0% to 24.4% (p<0.001), and similarly for women aged <40 and ≥40 years. Young women had Her2+ breast cancer twice as often as middle-aged women. Her2 amplification was present in 4.6% of cases scored 0 with IHC, while the corresponding proportions for scores 1+, 2+ and 3+ were 36.0%, 83.7% and 96.8%, respectively. All Her2 amplified cases, both true positive and false negative, had a significantly worse BCSS than the true negative cases

Local recurrence after breast conserving surgery in breast cancer

The general aim of this thesis was to gain increased insight into the problem of local recurrences after breast conserving surgery for breast cancer. In a population-based cohort of 4,694 women with invasive breast cancer, operated in 1981 to 1990 and followed through 1997, we studied how breast conserving surgery had been adopted into clinical practice. As adoption became more widespread, the indications for this type of surgery broadened. A simultaneous moderate impairment of the results was noted. Generally, the risk of local recurrence was higher than expected, but the estimated survival rates were gratifying. The overall risk of local recurrence was 9.2% at five years and 2 1. 1% at ten years, and the breast cancer-specific survival was 93.3% and 85.2% at five and ten years, respectively. A large proportion of the women had non- protocol treatment; nearly 30% were not given radiotherapy. Prognosis and prognostic factors after a local recurrence in the breast were studied in 391 women from a population-based cohort of 6,613 women. The prognosis differed notably between the different subgroups of breast recurrences, the subgroups being defined by time to and location of recurrence. Radiotherapy prevented or delayed the appearance of a local recurrence, but had little influence on the breast cancer-specific survival in women who experienced a local recurrence. The strongest independent prognostic factors for breast cancer-specific survival were time to local recurrence and Nottingham Prognostic Index. In the cohort of 6,613 women, 92 women experienced a local recurrence in the axilla. The overall risk of axillary recurrence in the cohort was 1.0% at five years and 1.7% at ten years. The major risk factors for axillary recurrence were low age, large tumour size and minor or no axillary surgery, while radiotherapy to the breast reduced the risk of axillary recurrence. The breast cancer-specific survival after axillary recurrence was poor, 59.2% and 43.5% at five and ten years, respectively. In an analysis of risk factors for local recurrence including 491 cases and 1,098 controls from a cohort of 7,502 women with invasive or non-invasive breast cancer, multivariate analysis showed low age, multicentricity and unclear/unknown surgical margins to be associated with an increased risk of local recurrence, while radiotherapy to the breast and adjuvant hormonal therapy were protective. Cancer in situ was not associated with a higher risk of local recurrence than invasive cancer. Nottingham Histologic Grade and Nottingham Prognostic Index were not helpful in determining the risk of local recurrence. The time relation between local recurrences and distant metastases was studied in a cohort of 5,496 women with invasive breast cancers. Women who had experienced a local recurrence had a higher hazard rate of distant metastases than women with no local recurrence, and the hazard rate curve showed two peaks, at three and seven years after the primary operation. In women with early breast cancer who had experienced a local recurrence, the second peak represented approximately half of the documented distant metastases, and may be explained by dissemination from the local recurrences

Effect of selective serotonin reuptake inhibitors use on endocrine therapy adherence and breast cancer mortality:a population-based study

The purpose of the study was to investigate whether the concomitant use of selective serotonin reuptake inhibitors (SSRI) with tamoxifen influences the risk of death due to breast cancer, and we also investigated the association between SSRI use and adherence to oral endocrine therapy (ET). We analyzed data from BCBaSe Sweden, which is a database created by the data linkage of Registries from three different regions of Sweden. To investigate the association between ET adherence and SSRI use, we included all women who were diagnosed with non-distant metastatic ER-positive invasive breast cancer from July 2007 to July 2011 and had at least one dispensed prescription of oral tamoxifen or aromatase inhibitor. To investigate the role of concurrent administration of SSRI and tamoxifen on breast cancer prognosis, we performed a nested case-control study. In the adherence cohort, 9104 women were included in the analyses. Women who received SSRI, either before or after breast cancer diagnosis, were at higher risk for low adherence to ET. However, when the overlapping period between SSRI use and ET was &gt; 50 %, no excess risk for low adherence was observed. Non-adherence (&lt; 80 %) to ET was significantly associated with worse breast cancer survival (OR 4.07; 95 % CI 3.27-5.06). In the case-control study, 445 cases and 11125 controls were included. The concomitant administration of SSRI and tamoxifen did not influence breast cancer survival, neither in short-term (OR 1.41; 95 % CI 0.74-2.68) nor in long-term SSRI users (OR 0.85; 95 % CI 0.35-2.08). Concomitant SSRI and tamoxifen use does not seem to increase risk for death due to breast cancer. Given the positive association between continuing antidepressive pharmacotherapy for a longer period of time and adherence to ET, it is essential to capture and treat depression in breast cancer patients to secure adherence to ET