E. Jane Macaskill

Letrozole Suppresses Plasma Estradiol and Estrone Sulphate More Completely Than Anastrozole in Postmenopausal Women With Breast Cancer

PURPOSE To compare the effects of anastrozole and letrozole on plasma estradiol (E2) and estrone sulfate (E1S) levels. PATIENTS AND METHODS Fifty-four postmenopausal women with estrogen receptor-positive breast cancer receiving aromatase inhibitors (AIs) as part of their adjuvant therapy were randomly assigned to receive either 3 months of anastrozole (1 mg) followed by 3 months of letrozole (2.5 mg), both given orally once daily, or 3 months of the opposite sequence. Blood was taken at the same time and the same day of the week from each patient, before and after 3 months of each drug, and plasma levels of E2 and E1S were determined using highly sensitive radioimmunoassays. RESULTS There were 27 patients in each group. The mean age of the patients was 63 years (range, 49 to 83 years). Baseline E2 levels ranged from 3 pmol/L to 91 pmol/L with a mean of 25.7 pmol/L. Only one of 54 (2%) patients had an E2 value >or= 3 pmol/L after receiving letrozole, versus 20 of 54 (37%) patients after receiving anastrozole (P < .001). Extrapolation revealed a mean E2 level after anastrozole treatment of 2.71 pmol/L (range, 2.38 to 3.08 pmol/L). Following letrozole, it was 1.56 pmol/L (range, 1.37 to 1.78 pmol/L). Mean residual E2 was 10.1% for anastrozole and 5.9% for letrozole. Residual E1S levels were 4.6% for anastrozole and 2.0% for letrozole (P = .001). CONCLUSION Letrozole reduces plasma E2 and E1S levels to a significantly greater extent than anastrozole in postmenopausal women taking AIs as part of their adjuvant therapy for hormone receptor-positive breast cancer.

Correcting for intra-experiment variation in Illumina BeadChip data is necessary to generate robust gene-expression profiles

BackgroundMicroarray technology is a popular means of producing whole genome transcriptional profiles, however high cost and scarcity of mRNA has led many studies to be conducted based on the analysis of single samples. We exploit the design of the Illumina platform, specifically multiple arrays on each chip, to evaluate intra-experiment technical variation using repeated hybridisations of universal human reference RNA (UHRR) and duplicate hybridisations of primary breast tumour samples from a clinical study.ResultsA clear batch-specific bias was detected in the measured expressions of both the UHRR and clinical samples. This bias was found to persist following standard microarray normalisation techniques. However, when mean-centering or empirical Bayes batch-correction methods (ComBat) were applied to the data, inter-batch variation in the UHRR and clinical samples were greatly reduced. Correlation between replicate UHRR samples improved by two orders of magnitude following batch-correction using ComBat (ranging from 0.9833-0.9991 to 0.9997-0.9999) and increased the consistency of the gene-lists from the duplicate clinical samples, from 11.6% in quantile normalised data to 66.4% in batch-corrected data. The use of UHRR as an inter-batch calibrator provided a small additional benefit when used in conjunction with ComBat, further increasing the agreement between the two gene-lists, up to 74.1%.ConclusionIn the interests of practicalities and cost, these results suggest that single samples can generate reliable data, but only after careful compensation for technical bias in the experiment. We recommend that investigators appreciate the propensity for such variation in the design stages of a microarray experiment and that the use of suitable correction methods become routine during the statistical analysis of the data.

Neoadjuvant Use of Endocrine Therapy in Breast Cancer

Abstract:  Neoadjuvant endocrine therapy is becoming increasingly popular as a safe and effective alternative to chemotherapy in selected patients. Large randomized studies have been published comparing tamoxifen with steroidal and nonsteroidal aromatase inhibitors, with favorable results for aromatase inhibitors letrozole, anastrozole, and exemestane. Endocrine therapy can be used in the neoadjuvant setting for conversion of inoperable breast tumors to operable, and from potential mastectomy to breast‐conserving surgery. The use of endocrine agents in this setting also provides an opportunity for the study of their biological effects upon tumor.

DCIS and aromatase inhibitors

In patients with hormone receptor positive DCIS tamoxifen reduces recurrence rates by almost 50%. Few data are available with aromatase inhibitors from randomised studies. In the ATAC study there were three DCIS lesions in the anastrozole arm and four in the tamoxifen arm in the women with ER positive invasive cancer. In the MA17 study which randomised patients to up to 5 years of letrozole or placebo there was only one DCIS event in the contralateral breast in patients taking letrozole and five on placebo. There were also four patients in this study who had DCIS in the conserved breast on placebo and none in the letrozole treated group. The few clinical data that are available therefore suggest the aromatase inhibitors are likely to be effective in DCIS. A histological review of a study of 206 postmenopausal women with invasive oestrogen receptor positive breast cancer who were randomised as part of a 14 day preoperative study to receive 2.5mg of letrozole or 1mg of anastrozole identified 27 patients with 28 pairs of tumours in whom there was sufficient ER positive DCIS in invasive cancer in the initial core biopsy and in the subsequent surgery specimen, to evaluate for PgR activity and proliferation. Within the DCIS both aromatase inhibitors significantly reduced PgR expression and both drugs also produced a significant fall in proliferation. There was a moderate degree of agreement between the fall in PgR in both the invasive cancer and DCIS (Kappa=0.5; p=0.0013) and between the fall in proliferation and between the invasive and in situ components (correlation coefficient=0.68; p<0.001). This study has shown significant effects of aromatase inhibitors on DCIS indicating that these agents are therapeutically active in this condition.

Surgical issues surrounding use of aromatase inhibitors

There are important surgical issues related to the use of the third generation aromatase inhibitors in both the neoadjuvant and adjuvant settings. Neoadjuvant hormone therapy is effective at downstaging tumours, particularly large tumours initially thought to be inoperable or requiring mastectomy. Randomised trials have shown that the newer aromatase inhibitors letrozole and anastrozole increase the numbers of women who are suitable for breast-conservation compared with tamoxifen, and that letrozole is superior to tamoxifen in terms of clinical response. Aromatase inhibitors are most effective in ER-rich tumours and are clinically and biologically effective in both HER2 positive and negative tumours, whereas HER2 positive tumours show a level of resistance to tamoxifen. In neoadjuvant studies comparing aromatase inhibitors with tamoxifen, the duration of use has been 3-4 months, by which time any response is usually evident but longer treatment periods produce continued shrinkage and response. The re-excision rate following breast conservation surgery after neoadjuvant hormone therapy is favourable compared with the rates following immediate wide local excision. Local recurrence rates are acceptable in patients undergoing neoadjuvant therapy and breast-conserving surgery providing post-operative radiotherapy is given. Adjuvant aromatase inhibitors, as well as having an effect on metastatic disease and survival, reduce local and regional recurrence.

For the use of ultrasound by surgeons

There is an increasing demand upon radiology departments for use of ultrasound as part of triple assessment of symptomatic breast disease. It has been shown that in the context of proper training both surgeons and radiologists achieve comparably high diagnostic sensitivity and specificity with ultrasound. This article outlines the arguments in favour of the use of ultrasound by surgeons in the breast clinic for diagnostic and therapeutic purposes.

Endocrine therapy in DCIS: how do we proceed?

There is variation between and within countries in the use of endocrine treatment of ductal carcinoma in situ (DCIS). Although it is known that tamoxifen reduces recurrence after excision + ⁄ radiotherapy for DCIS the morbidity is such that in the United Kingdom, tamoxifen is not recommended for adjuvant use in DCIS. There are limited data on aromatase inhibitors but they are clearly active in DCIS in relation to both treatment and prevention. In this edition of The Breast Journal, Chlebowski and Col present the arguments for the use of exemestane in postmenopausal women who have undergone mastectomy for DCIS (1). By pooling data from studies comparing aromatase inhibitors with placebo (2–5), they demonstrate an overall odds ratio of 0.506 (0.357– 0.716; p < 0.001) for reduction in contralateral invasive breast cancer if aromatase inhibitors are used. The authors conclude that exemestane should be considered as standard therapy because it reduces the risk of contralateral breast cancer in patients who have undergone mastectomy for DCIS. Only two of the studies which they have pooled, include data from studies using exemestane, and analysis restricted only to these studies (2,3) contains a combined total of more than 6,000 patients had an overall odds ratio for contralateral cancers of 0.322 (95% CI 0.172–0.604) (p-value not stated). There are no current trials that address the issue of endocrine treatment for prevention of contralateral disease for patients who have undergone mastectomy for DCIS. The issue is therefore are there data that can be extrapolated that are applicable to this group of patients? The two exemestane studies included MAP3, a prevention trial (3) and the NSABP B33 trial (2) that compared placebo with extended adjuvant exemestane in invasive breast cancer. Although these studies show the activity of exemestane compared with placebo, neither study included patients with DCIS. The NSABP B33 study population was limited to patients who had prior invasive cancer, and thus any results may not necessarily be transferable to a population of patients with previous in situ disease. NSABP B33 suffered from early unblinding with patients switching to active treatment as the results from the MA17 extended adjuvant letrozole study were published. This resulted in 44% of the placebo patients in NSABP B33 switching to exemestane. The intention-to-treat analysis therefore potentially underestimates the effect of the active drug because of the high percentage switching to exemestane. The number of contralateral breast cancers in NSABP B33 was very small at 30 months follow-up, although there was a trend to a benefit with exemestane (two contralateral cancers with exemestane versus eight with placebo; p = 0.05). In the NCIC-CTG MAP3 prevention trial (3), patients considered to be at high risk of breast cancer were randomized to 5 years exemestane versus placebo. This study group included only 56 women in both arms who had undergone mastectomy for DCIS. Of note in this prevention trial there was a 30% dropout rate of patients taking exemestane due to side effects, higher than that recorded in previously treated populations such as in the NSABP B33, where tolerability was better. At a median of 35 months followup, there was a significant reduction in events (HR 0.35, 95% CI 0.18–0.70; p = 0.002) in the exemestane arm in all patients. Notably, this reduction was only significant in preventing ER-positive disease (HR 0.27, 95% CI 0.12–0.60; p < 0.001) but not for ER-negative disease (HR 0.80, 95% CI 0.21–2.98; p = 0.74). Patients who had previous DCIS were excluded from the analysis of development of new DCIS or invasive disease with DCIS component. It is not stated whether any disease detected in this study occurred in patients who had previously been diagnosed with DCIS. There was no reduction in the rate of invasive breast cancer in patients who had previous atypical ductal hyperplasia (ADH), atypical lobular hyperplasia or lobular carcinoma in situ (LCIS), nor was there any reduction in new DCIS events in the whole group. It is difficult therefore to extrapolate the true value of exemestane from this study to patients with previous DCIS. DOI: 10.1111/j.1524-4741.2012.01263.x

Preoperative Endocrine Therapy: Preferred Therapy for Whom?

Neoadjuvant endocrine therapy is safe and can be effective in many postmenopausal women with estrogen receptor positive breast cancer. There are limited data available for premenopausal women taking aromatase inhibitors in combination with estrogen suppression. Letrozole, anastrozole, and exemestane have all been shown to be equivalent or superior to tamoxifen in relatively small neoadjuvant trials in postmenopausal women. Tumor factors that appear to have good response are estrogen receptor positivity, characteristics consistent with the so-called Luminal A subtype and lobular carcinomas. Response to neoadjuvant treatment may inform decision making regarding adjuvant treatment, which should include radiotherapy following breast-conserving surgery, or mastectomy, made feasible by neoadjuvant treatment to maintain low local recurrence rates. Chemotherapy may also be required in some cases based on the biological characteristics of the residual tumor and the extent of residual disease.

Endocrine therapy in DCIS

There is variation between and within countries in the use of endocrine treatment of ductal carcinoma in situ (DCIS). Although it is known that tamoxifen reduces recurrence after excision + ⁄ radiotherapy for DCIS the morbidity is such that in the United Kingdom, tamoxifen is not recommended for adjuvant use in DCIS. There are limited data on aromatase inhibitors but they are clearly active in DCIS in relation to both treatment and prevention. In this edition of The Breast Journal, Chlebowski and Col present the arguments for the use of exemestane in postmenopausal women who have undergone mastectomy for DCIS (1). By pooling data from studies comparing aromatase inhibitors with placebo (2–5), they demonstrate an overall odds ratio of 0.506 (0.357– 0.716; p < 0.001) for reduction in contralateral invasive breast cancer if aromatase inhibitors are used. The authors conclude that exemestane should be considered as standard therapy because it reduces the risk of contralateral breast cancer in patients who have undergone mastectomy for DCIS. Only two of the studies which they have pooled, include data from studies using exemestane, and analysis restricted only to these studies (2,3) contains a combined total of more than 6,000 patients had an overall odds ratio for contralateral cancers of 0.322 (95% CI 0.172–0.604) (p-value not stated). There are no current trials that address the issue of endocrine treatment for prevention of contralateral disease for patients who have undergone mastectomy for DCIS. The issue is therefore are there data that can be extrapolated that are applicable to this group of patients? The two exemestane studies included MAP3, a prevention trial (3) and the NSABP B33 trial (2) that compared placebo with extended adjuvant exemestane in invasive breast cancer. Although these studies show the activity of exemestane compared with placebo, neither study included patients with DCIS. The NSABP B33 study population was limited to patients who had prior invasive cancer, and thus any results may not necessarily be transferable to a population of patients with previous in situ disease. NSABP B33 suffered from early unblinding with patients switching to active treatment as the results from the MA17 extended adjuvant letrozole study were published. This resulted in 44% of the placebo patients in NSABP B33 switching to exemestane. The intention-to-treat analysis therefore potentially underestimates the effect of the active drug because of the high percentage switching to exemestane. The number of contralateral breast cancers in NSABP B33 was very small at 30 months follow-up, although there was a trend to a benefit with exemestane (two contralateral cancers with exemestane versus eight with placebo; p = 0.05). In the NCIC-CTG MAP3 prevention trial (3), patients considered to be at high risk of breast cancer were randomized to 5 years exemestane versus placebo. This study group included only 56 women in both arms who had undergone mastectomy for DCIS. Of note in this prevention trial there was a 30% dropout rate of patients taking exemestane due to side effects, higher than that recorded in previously treated populations such as in the NSABP B33, where tolerability was better. At a median of 35 months followup, there was a significant reduction in events (HR 0.35, 95% CI 0.18–0.70; p = 0.002) in the exemestane arm in all patients. Notably, this reduction was only significant in preventing ER-positive disease (HR 0.27, 95% CI 0.12–0.60; p < 0.001) but not for ER-negative disease (HR 0.80, 95% CI 0.21–2.98; p = 0.74). Patients who had previous DCIS were excluded from the analysis of development of new DCIS or invasive disease with DCIS component. It is not stated whether any disease detected in this study occurred in patients who had previously been diagnosed with DCIS. There was no reduction in the rate of invasive breast cancer in patients who had previous atypical ductal hyperplasia (ADH), atypical lobular hyperplasia or lobular carcinoma in situ (LCIS), nor was there any reduction in new DCIS events in the whole group. It is difficult therefore to extrapolate the true value of exemestane from this study to patients with previous DCIS. DOI: 10.1111/j.1524-4741.2012.01263.x