Jessica M. Engel

Breast Cancer Subtypes Based on ER/PR and Her2 Expression: Comparison of Clinicopathologic Features and Survival

OBJECTIVE To compare the clinicopathologic features and survival in the four breast cancer subtypes defined by immunohistochemistry (IHC) expression of estrogen receptor (ER) or progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2): ER/PR+, Her2+; ER/PR+, Her2-; ER/PR-, Her2+; and ER/PR-, Her2-. METHODS A 7-year retrospective study of 1134 invasive breast cancer subjects. Clinical and pathologic features and survival of the four subtypes were compared. RESULTS Using ER/PR+ and Her2- as a reference, ER/PR-, Her2- had the worst overall survival (hazard ratio, 1.8; 95% confidence interval [CI], 1.06-3.2) and the worst disease-free survival (hazard ratio, 1.5; 95% CI, 0.8-3.0). In ER/PR+, Her2-, chemotherapy conferred significant overall and disease-free survival advantages. Subtype comparison revealed statistically significant differences in outcomes. CONCLUSION The triple negative subtype has the worst overall and disease free survival. Efforts should be directed at standardization of current testing methods and development of more reliable and reproducible testing.

Variability in Reexcision Following Breast Conservation Surgery

CONTEXT Health care reform calls for increasing physician accountability and transparency of outcomes. Partial mastectomy is the most commonly performed procedure for invasive breast cancer and often requires reexcision. Variability in reexcision might be reflective of the quality of care. OBJECTIVE To assess hospital and surgeon-specific variation in reexcision rates following partial mastectomy. DESIGN, SETTING, AND PATIENTS An observational study of breast surgery performed between 2003 and 2008 intended to evaluate variability in breast cancer surgical care outcomes and evaluate potential quality measures of breast cancer surgery. Women with invasive breast cancer undergoing partial mastectomy from 4 institutions were studied (1 university hospital [University of Vermont] and 3 large health plans [Kaiser Permanente Colorado, Group Health, and Marshfield Clinic]). Data were obtained from electronic medical records and chart abstraction of surgical, pathology, radiology, and outpatient records, including detailed surgical margin status. Logistic regression including surgeon-level random effects was used to identify predictors of reexcision. MAIN OUTCOME MEASURE Incidence of reexcision. RESULTS A total of 2206 women with 2220 invasive breast cancers underwent partial mastectomy and 509 patients (22.9%; 95% CI, 21.2%-24.7%) underwent reexcision (454 patients [89.2%; 95% CI, 86.5%-91.9%] had 1 reexcision, 48 [9.4%; 95% CI, 6.9%-12.0%] had 2 reexcisions, and 7 [1.4%; 95% CI, 0.4%-2.4%] had 3 reexcisions). Among all patients undergoing initial partial mastectomy, total mastectomy was performed in 190 patients (8.5%; 95% CI, 7.2%-9.5%). Reexcision rates for margin status following initial surgery were 85.9% (95% CI, 82.0%-89.8%) for initial positive margins, 47.9% (95% CI, 42.0%-53.9%) for less than 1.0 mm margins, 20.2% (95% CI, 15.3%-25.0%) for 1.0 to 1.9 mm margins, and 6.3% (95% CI, 3.2%-9.3%) for 2.0 to 2.9 mm margins. For patients with negative margins, reexcision rates varied widely among surgeons (range, 0%-70%; P = .003) and institutions (range, 1.7%-20.9%; P < .001). Reexcision rates were not associated with surgeon procedure volume after adjusting for case mix (P = .92). CONCLUSION Substantial surgeon and institutional variation were observed in reexcision following partial mastectomy in women with invasive breast cancer.

Diabetes and cancer II: role of diabetes medications and influence of shared risk factors

An association between type 2 diabetes mellitus (DM) and cancer has long been postulated, but the biological mechanism responsible for this association has not been defined. In part one of this review, we discussed the epidemiological evidence for increased risk of cancer, decreased cancer survival, and decreased rates of cancer screening in diabetic patients. Here we review the risk factors shared by cancer and DM and how DM medications play a role in altering cancer risk. Hyperinsulinemia stands out as a major factor contributing to the association between DM and cancer, and modulation of circulating insulin levels by DM medications appears to play an important role in altering cancer risk. Drugs that increase circulating insulin, including exogenous insulin, insulin analogs, and insulin secretagogues, are generally associated with an increased cancer risk. In contrast, drugs that regulate insulin signaling without increasing levels, especially metformin, appear to be associated with a decreased cancer risk. In addition to hyperinsulinemia, the effect of DM medications on other shared risk factors including hyperglycemia, obesity, and oxidative stress as well as demographic factors that may influence the use of certain DM drugs in different populations are described. Further elucidation of the mechanisms behind the association between DM, cancer, and the role of DM medications in modulating cancer risk may aid in the development of better prevention and treatment options for both DM and cancer. Additionally, incorporation of DM medication use into cancer prediction models may lead to the development of improved risk assessment tools for diabetic patients.

Type 2 diabetes mellitus, glycemic control, and cancer risk

Type 2 diabetes mellitus is characterized by prolonged hyperinsulinemia, insulin resistance, and progressive hyperglycemia. Disease management relies on glycemic control through diet, exercise, and pharmacological intervention. The goal of the present study was to examine the effects of glycemic control and the use of glucose-lowering medication on the risk of breast, prostate, and colon cancer. Patients diagnosed with type 2 diabetes mellitus (N=9486) between 1 January 1995 and 31 December 2009 were identified and data on glycemic control (hemoglobin A1c, glucose), glucose-lowering medication use (insulin, metformin, sulfonylurea), age, BMI, date of diabetes diagnosis, insurance status, comorbidities, smoking history, location of residence, and cancer diagnoses were electronically abstracted. Cox proportional hazards regression modeling was used to examine the relationship between glycemic control, including medication use, and cancer risk. The results varied by cancer type and medication exposure. There was no association between glycemic control and breast or colon cancer; however, prostate cancer risk was significantly higher with better glycemic control (hemoglobin A1c⩽7.0%). Insulin use was associated with increased colon cancer incidence in women, but not with colon cancer in men or breast or prostate cancer risk. Metformin exposure was associated with reduced breast and prostate cancer incidence, but had no association with colon cancer risk. Sulfonylurea exposure was not associated with risk of any type of cancer. The data reported here support hyperinsulinemia, rather than hyperglycemia, as a major diabetes-related factor associated with increased risk of breast and colon cancer. In contrast, hyperglycemia appears to be protective in the case of prostate cancer.

Cardiovascular toxicity associated with adjuvant trastuzumab therapy: prevalence, patient characteristics, and risk factors.

Before the advent of the human epidermal growth factor receptor 2 (HER2)-targeted monoclonal antibody trastuzumab, HER2-positive breast cancers were difficult to treat and had a poor prognosis. Adjuvant trastuzumab is now an important part of the treatment regimen for many women with HER2-positive breast cancer and has undoubtedly resulted in a significant improvement in prognosis, but it is associated with a risk for cardiotoxicity. In this review, we describe the prevalence, patient characteristics, and risk factors for cardiotoxicity associated with use of adjuvant trastuzumab. Understanding risk factors for trastuzumab-induced cardiotoxicity and appropriate patient monitoring during trastuzumab treatment allows for safe and effective use of this important adjuvant therapy.

Mammography utilization: patient characteristics and breast cancer stage at diagnosis.

OBJECTIVE Missed mammograms represent missed opportunities for earlier breast cancer diagnosis. The purposes of this study were to identify patient characteristics associated with missed mammograms and to examine the association between missed mammograms and breast cancer stage at diagnosis. MATERIALS AND METHODS Mammography frequency and cancer stage were retrospectively examined in 1368 cases of primary breast cancer diagnosed at our clinic from 2002 to 2008. RESULTS Regardless of age (median, 62.7 years), 1428 women who underwent mammography were more likely to have early-stage (stage 0-II) breast cancer at diagnosis than were those who did not undergo mammography (p < 0.001). Similarly, the number of mammographic examinations in the 5 years before diagnosis was inversely related to stage: 57.3% (94/164) of late-stage cancers were diagnosed in women missing their last five annual mammograms. In a multivariate analysis, family history of breast cancer was most predictive of undergoing mammography (odds ratio, 3.492; 95% CI, 2.616-4.662; p < 0.0001) followed by number of medical encounters (odds ratio, 1.022; 95% CI, 1.017-1.027; p < 0.0001). Time to travel to the nearest mammography center was also predictive of missing mammograms: Each additional minute of travel time decreased the odds of undergoing at least one mammographic examination in the 5 years before cancer diagnosis (odds ratio, 0.990; 95% CI, 0.986-0.993; p < 0.0001). CONCLUSION Missing a mammogram, even in the year before a breast cancer diagnosis, increases the chance of a cancer diagnosis at a later stage. Interventions to encourage use of mammography may be of particular benefit to women most likely to miss mammograms, including those with no family history of breast cancer, fewer encounters with the health care system, and greater travel distance to the mammography center.

Clustering of venous thrombosis events at the start of tamoxifen therapy in breast cancer: A population-based experience

INTRODUCTION The epidemiology of tamoxifen and venous thromboembolism (VTE) is not well understood, and most data on tamoxifen toxicity are from adjuvant clinical trials. This study examined the relationship between the duration of tamoxifen use in female patients with breast cancer and the risk of VTE in a large population-based setting. MATERIALS AND METHODS Retrospective electronic data extraction on tamoxifen utilization was undertaken among a cohort of 3572 women with breast cancer seen at Marshfield Clinic between January 1, 1994 and June 31, 2009. Observational follow-up extended until February, 2010. RESULTS On initial exposure to tamoxifen, women had a clustering of VTE events. Cox proportional hazards regression, adjusting for multiple clinically-important covariates including age, body mass index, cancer stage, and concurrent diabetes, demonstrated that as use of tamoxifen continued in those without earlier VTE events, risk of subsequent VTE gradually increased, albeit at a lower rate (hazard ratio per year of tamoxifen duration=1.225, P <0.0001). CONCLUSIONS In our study population, initiating tamoxifen coincided with an initial clustering of VTE events, with risks due specifically to tamoxifen, increasing during continued exposure. Evidence suggested that the VTE clustering occurred in high risk individuals at initiation of tamoxifen therapy. Careful selection of patients for whom tamoxifen therapy is appropriate based on susceptibility to VTE is thus required prior to initiation of therapy.

Survival Comparisons for Breast Conserving Surgery and Mastectomy Revisited: Community Experience and the Role of Radiation Therapy

Objectives Evidence suggests superiority of breast conserving surgery (BCS) plus radiation over mastectomy alone for treatment of early stage breast cancer. Whether the superiority of BCS plus radiation is related to the surgical approach itself or to the addition of adjuvant radiation therapy following BCS remains unclear. Materials and Methods We conducted a retrospective cohort study of women with breast cancer diagnosed from 1994–2012. Data regarding patient and tumor characteristics and treatment specifics were captured electronically. Kaplan-Meier survival analyses were performed with inverse probability of treatment weighting to reduce selection bias effects in surgical assignment. Results Data from 5335 women were included, of which two-thirds had BCS and one-third had mastectomy. Surgical decision trends changed over time with more women undergoing mastectomy in recent years. Women who underwent BCS versus mastectomy differed significantly regarding age, cancer stage/grade, adjuvant radiation, chemotherapy, and endocrine treatment. Overall survival was similar for BCS and mastectomy. When BCS plus radiation was compared to mastectomy alone, 3-, 5-, and 10-year overall survival was 96.5% vs 93.4%, 92.9% vs 88.3% and 80.9% vs 67.2%, respectively. Conclusion These analyses suggest that survival benefit is not related only to the surgery itself, but that the prognostic advantage of BCS plus radiation over mastectomy may also be related to the addition of adjuvant radiation therapy. This conclusion requires prospective confirmation in randomized trials.

Breast cancer incidence before and after diagnosis of type 2 diabetes mellitus in women: increased risk in the prediabetes phase

The physiological changes associated with type 2 diabetes mellitus begin before disease onset, yet few have examined the incidence of cancer both before and after diabetes onset. We examined the temporal relationship between diabetes and breast cancer risk. Breast cancer risk was assessed in a retrospective cohort study using patient data from the Marshfield Clinic electronic medical record including 5423 women who developed diabetes between 1 January 1995 and 31 December 2009 (reference date) and 26 346 nondiabetic women matched by age, smoking history, residence, and reference date. Breast cancer risk was assessed before and after reference date, adjusting for matching variables, BMI, insurance status, and comorbidities. Primary outcomes included hazard ratio (HR) and number of women needed to be exposed to diabetes for one additional person to be harmed – that is, develop breast cancer (NNEH). HR for breast cancer before diabetes diagnosis was 1.16 (95% CI 1.03–1.31, P=0.0150) and NNEH was 99 at time of diabetes onset. HR for breast cancer after diabetes diagnosis was not significant at 1.07 (95% CI 0.90–1.28, P=0.422), and NNEH was 350 at 10 years post diabetes onset. Diabetic women are at the greatest increased risk of breast cancer near the time of diabetes diagnosis. The comparative NNEH increased shortly after diagnosis and as the duration of diabetes increased. Breast cancer risk appears to be increased during the prediabetes phase, waning after diagnosis, raising important issues regarding timing of breast cancer prevention interventions in women with diabetes.

Simplifying the TNM System for Clinical Use in Differentiated Thyroid Cancer

PURPOSE The TNM stratification has been found useful at stratifying patients with differentiated thyroid carcinoma (DTC) into prognostic risk groups. However, it is cumbersome to implement clinically given the large number of bins within this system and the complicated system of arriving at stage information. PATIENTS AND METHODS We decided to quantify each variable in this system to arrive at a simplified quantitative alternative to the TNM system (QTNM) and compare this with the conventional system. We used our electronic record system to identify 614 cases of DTC managed at our institution from 1987 to 2006. Cancer-specific survival (CSS) and disease-free survival (DFS) were calculated by the Kaplan-Meier method, and a simplified QTNM score was devised using a Cox proportional hazards model. RESULTS We were able to quantify the TNM system as follows: 4 points each for age older than 45 years and presence of neck nodal metastases while 6 points for tumor size larger than 4 cm or extrathyroidal extension and 1 point for nonpapillary DTC. A sum of 0 to 5 points was low risk, 6 to 10 points intermediate, and 11 to 15 points high risk. Comparison with the conventional TNM system and two other systems revealed similar or better discrimination with the QTNM and this discrimination was maintained when this risk stratification was applied to a unique validation set. CONCLUSION The QTNM system as opposed to the conventional TNM system seems to be a simple and effective method for risk stratification for both recurrence and cancer-specific mortality.