Concordance of Immunohistochemistry-Based and Gene Expression-Based Subtyping in Breast Cancer.

Background: Use of immunohistochemistry-based surrogates of molecular breast cancer subtypes is common in research and clinical practice, but information on their comparative validity and prognostic capacity is scarce. Methods: Data from 2 PAM50-subtyped Swedish breast cancer cohorts were used: Stockholm tamoxifen trial-3 with 561 patients diagnosed 1976-1990 and Clinseq with 237 patients diagnosed 2005-2012. We evaluated 3 surrogate classifications; the immunohistochemistry-3 surrogate classifier based on estrogen receptor, progesterone receptor, and HER2 and the St. Gallen and Prolif surrogate classifiers also including Ki-67. Accuracy, kappa, sensitivity, and specificity were computed as compared with PAM50. Alluvial diagrams of misclassification patterns were plotted. Distant recurrence-free survival was assessed using Kaplan-Meier plots, and tamoxifen treatment benefit for luminal subtypes was modeled using flexible parametric survival models. Results: The concordance with PAM50 ranged from poor to moderate (kappa = 0.36-0.57, accuracy = 0.54-0.75), with best performance for the Prolif surrogate classification in both cohorts. Good concordance was only achieved when luminal subgroups were collapsed (kappa = 0.71-0.69, accuracy = 0.90-0.91). The St. Gallen surrogate classification misclassified luminal A into luminal B; the reverse pattern was seen with the others. In distant recurrence-free survival, surrogates were more similar to each other than PAM50. The difference in tamoxifen treatment benefit between luminal A and B for PAM50 was not replicated with any surrogate classifier. Conclusions: All surrogate classifiers had limited ability to distinguish between PAM50 luminal A and B, but patterns of misclassifications differed. PAM50 subtyping appeared to yield larger separation of survival between luminal subtypes than any of the surrogate classifications.

Family History, Reproductive, and Lifestyle Risk Factors for Fibroadenoma and Breast Cancer.

BACKGROUND: To understand which breast cancer (BC) risk factors also increase the risk of fibroadenoma and investigate whether these factors have the same effect in BC patients with previous fibroadenoma. METHODS: Using multistate survival analysis on a large dataset (n = 58 322), we examined the effects of BC risk factors on transitions between three states: event-free, biopsy-confirmed fibroadenoma, and BC. Hazard ratios and corresponding 95% confidence intervals associated with covariate effects were estimated. Median follow-up time was 25.3 years. RESULTS: The mean ages at diagnosis of fibroadenoma and BC were 42.6 and 48.3 years, respectively. Participant characteristics known to increase the risk of BC were found to increase the risk of fibroadenoma (family history of BC and higher education). Participant characteristics known to confer protective effects for BC (older age at menarche, more children, and larger childhood body size) were found to reduce fibroadenoma risk. The effect sizes associated with the direct transitions from event-free to fibroadenoma and BC were generally not different for the covariates tested. Age at fibroadenoma diagnosis was associated with the transition from fibroadenoma to BC (hazard ratioper year increase = 1.07 [95% confidence interval = 1.03 to 1.12]). CONCLUSION: We showed that biopsy-confirmed fibroadenomas shared many risk factors with BC. More work is needed to understand the relationships between fibroadenoma and BC to identify women who are at high risk of developing BC after a fibroadenoma diagnosis.

Tamoxifen therapy benefit for patients with 70-gene signature high and low risk.

BACKGROUND: Breast cancer molecular prognostic tools that predict recurrence risk have mainly been established on endocrine-treated patients and thus are not optimal for the evaluation of benefit from endocrine therapy. The Stockholm tamoxifen (STO-3) trial which randomized postmenopausal node-negative patients to 2-year tamoxifen (followed by an optional randomization for an additional 3-year tamoxifen vs nil), versus no adjuvant treatment, provides a unique opportunity to evaluate long-term 20-year benefit of endocrine therapy within prognostic risk classes of the 70-gene prognosis signature that was developed on adjuvantly untreated patients. METHODS: We assessed by Kaplan-Meier analysis 20-year breast cancer-specific survival (BCSS) and 10-year distant metastasis-free survival (DMFS) for 538 estrogen receptor (ER)-positive, STO-3 trial patients with retrospectively ascertained 70-gene prognosis classification. Multivariable analysis of long-term (20 years) BCSS by STO-3 trial arm in the 70-gene high-risk and low-risk subgroups was performed using Cox proportional hazard modeling adjusting for classical patient and tumor characteristics. RESULTS: Tamoxifen-treated, 70-gene low- and high-risk patients had 20-year BCSS of 90 and 83%, as compared to 80 and 65% for untreated patients, respectively (log-rank p < 0.0001). Notably, there is equivalent tamoxifen benefit in both high (HR 0.42 (0.21-0.86), p = 0.018) and low (HR 0.46 (0.25-0.85), p = 0.013) 70-gene risk categories even after adjusting for clinico-pathological factors for BCSS. Limited tamoxifen exposure as given in the STO-3 trial provides persistent benefit for 10-15 years after diagnosis in a time-varying analysis. 10-year DMFS was 93 and 85% for low- and high-risk tamoxifen-treated, versus 83 and 70% for low- and high-risk untreated patients, respectively (log-rank p < 0.0001). CONCLUSIONS: Patients with ER-positive breast cancer, regardless of high or low 70-gene risk classification, receive significant survival benefit lasting over 10 years from adjuvant tamoxifen therapy, even when given for a relatively short duration.

Molecular Differences between Screen-Detected and Interval Breast Cancers Are Largely Explained by PAM50 Subtypes.

Purpose: Interval breast cancer is of clinical interest, as it exhibits an aggressive phenotype and evades detection by screening mammography. A comprehensive picture of somatic changes that drive tumors to become symptomatic in the screening interval can improve understanding of the biology underlying these aggressive tumors.Experimental Design: Initiated in April 2013, Clinical Sequencing of Cancer in Sweden (Clinseq) is a scientific and clinical platform for the genomic profiling of cancer. The breast cancer pilot study consisted of women diagnosed with breast cancer between 2001 and 2012 in the Stockholm/Gotland regions. A subset of 307 breast tumors was successfully sequenced, of which 113 were screen-detected and 60 were interval cancers. We applied targeted deep sequencing of cancer-related genes; low-pass, whole-genome sequencing; and RNA sequencing technology to characterize somatic differences in the genomic and transcriptomic architecture by interval cancer status. Mammographic density and PAM50 molecular subtypes were considered.Results: In the univariate analyses, TP53, PPP1R3A, and KMT2B were significantly more frequently mutated in interval cancers than in screen-detected cancers. Acquired somatic copy number aberrations with a frequency difference of at least 15% between the two groups included gains in 17q23-q25.3 and losses in 16q24.2. Gene expression analysis identified 447 significantly differentially expressed genes, of which 120 were replicated in an independent microarray dataset. After adjusting for PAM50, most differences were no longer significant.Conclusions: Molecular differences by interval cancer status were observed, but they were largely explained by PAM50 subtypes. This work offers new insights into the biological differences between the two tumor groups. Clin Cancer Res; 23(10); 2584-92. ©2016 AACR.

Differences in survival for patients with familial and sporadic cancer.

Family history of cancer is a well-known risk factor but the role of family history in survival is less clear. The aim of this study was to investigate the association between family history and cancer survival for the common cancers in Sweden. Using the Swedish population-based registers, patients diagnosed with the most common cancers were followed for cancer-specific death during 1991-2010. We used multivariate proportional hazards (Cox) regression models to contrast the survival of patients with a family history of cancer (individuals whose parent or sibling had a concordant cancer) to the survival of patients without a family history. Family history of cancer had a modest protective effect on survival for breast cancer (hazard ratio (HR) = 0.88, 95% confidence interval (95% CI) = 0.81 to 0.96) and prostate cancer (HR = 0.82, 95% CI = 0.75 to 0.90). In contrast, family history of cancer was associated with worse survival for nervous system cancers (HR = 1.24, 95% CI = 1.05 to 1.47) and ovarian cancer (HR = 1.20, 95% CI = 1.01 to 1.43). Furthermore, the poorer survival for ovarian cancer was consistent with a higher FIGO stage and a greater proportion of more aggressive tumors of the serous type. The better survival for patients with a family history of breast and prostate cancer may be due to medical surveillance of family members. The poor survival for ovarian cancer patients with an affected mother or sister is multifactorial, suggesting that these cancers are more aggressive than their sporadic counterparts.

Clinically used breast cancer markers such as estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 are unstable throughout tumor progression.

PURPOSE To investigate whether hormonal receptors and human epidermal growth factor receptor 2 (HER2) change throughout tumor progression, because this may alter patient management. PATIENTS AND METHODS The study cohort included female patients with breast cancer in the Stockholm health care region who relapsed from January 1, 1997, to December 31, 2007. Either biochemical or immunohistochemical (IHC)/immunocytochemical (ICC) methods were used to determine estrogen receptor (ER), progesterone receptor (PR), and HER2 status, which was then confirmed by fluorescent in situ hybridization for IHC/ICC 2+ and 3+ status. Results ER (459 patients), PR (430 patients), and HER2 (104 patients) from both primary tumor and relapse were assessed, revealing a change in 32.4% (McNemar's test P < .001), 40.7% (P < .001), and 14.5% (P = .44) of patients, respectively. Assessment of ER (119 patients), PR (116 patients), and HER2 (32 patients) with multiple (from two to six) consecutive relapses showed an alteration in 33.6%, 32.0%, and 15.7% of patients, respectively. A statistically significant differential overall survival related to intraindividual ER and PR status in primary tumor and relapse (log-rank P < .001) was noted. In addition, women with ER-positive primary tumors that changed to ER-negative tumors had a significant 48% increased risk of death (hazard ratio, 1.48; 95% CI, 1.08 to 2.05) compared with women with stable ER-positive tumors. CONCLUSION Patients with breast cancer experience altered hormone receptor and HER2 status throughout tumor progression, possibly influenced by adjuvant therapies, which significantly influences survival. Hence, marker investigations at relapse may potentially improve patient management and survival.