EFFECT OF OBESITY ON ESTRADIOL DEPLETIONIN POSTMENOPAUSAL WOMEN WITH HORMONE-SENSITIVE EARLY BREAST CANCER TREATED WITHADJUVANT ANASTRAZOLE

Reham A. Salem 1 , Eman M. Mortada 2 , Lobna A. Abdelaziz 1 and Ola M Elfarargy 3 . 1. Clinical Oncology and Nuclear Medicine Department, Faculty of Medicine, Zagazig University, Egypt. 2. Community, Environmental and Occupational Medicine Department, Faculty of Medicine, Zagazig University. 3. Medical oncology department Faculty of Medicine, Zagazig University, Egypt. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Background: Obese BC patients have increased total body aromatization which leads to increased serum estrogen level when compared with non obese patients, Recently it has been shown that BMI has an impact on the efficacy of AIs, mainly Anastrazole, in patients with breast cancer Aim of the work: The aim of this study was to assess the effect of obesity on estradiol depletion in postmenopausal women with hormone-sensitive early breast cancer treated with Adjuvant upfront standard dose Anastrazole (1mg) after 6 months of treatment and its impact on survival. Patients and Methods: This prospective cohort study was conducted at the Clinical Oncology and Nuclear Medicine Department -Zagazig University Hospitals. During the period of March 2013 to November 2016. The study included 100 postmenopausal women with hormonal receptors positive early breast cancer who received upfront Anastrazole 1mg/d . Patients were classified into two groups according to BMI, non-obese (BMI<30kg/m2) and obese (BMI≥30kg/m2) according to the WHO, a baseline serum estradiol and FSH were obtained for every patient prior starting Anastrazole therapy. Patients were followed up and monitored after 6 months for changes in serum estradiol level and FSH level . The primary end point of the study was , detection of BMI variation and its relation to changes in serum Estradiol and FSH levels Secondary end point was to compare the OS, DFS and adverse events between the two treatment groups Results: One hundred patients were included, half of them were classified being obese with (BMI≥30 ) with mean BMI(35±5.8) while the other half was considered non obese (BMI<30) with mean BMI(24.5±4.4). Both groups were compared according to patient measures and tumor characteristics, regarding all ( 100 ) patients , Anastrazole significantly reduced the mean ESL from19.45±4.1 pg ml −1 to 11.13 ±3.1 pg ml −1 after 6 months of treatment (P <0.001). On the other hand , inverse changes in FSH serum level as the mean FSH serum level initially was 70.91±20.7 mIU ml −1 and then significantly increased to 75.78±19.3 mIU ml −1 after 6 months of treatment with Anastrazole (P <0.001). however after 6 months of Anastrazole treatment , the mean ESL of obese patients was significantly higher compared to non-obese patients (11.98 pg ml −1 VS 8.78 pg ml −1 ) (P <0.001). and this difference reflected by significantly lower serum FSH level in obese compared to non-obese patients (64.98±14.7 mIU ml −1 vs 87.53±17.6 mIU ml −1 ) (P <0.001). early results of survival analysis revealed 3y DFS in non-obese patients was 92% while it was 90% in obese patients with no significant difference between both groups (P=0.680) . 3y OS in non-

Introduction:-
In U.S Breast cancer is the most common malignancy and the second most frequent cause of cancer mortality in women. 1,2 And it is considered the first malignancy-affecting females in Egypt. 3 Obese postmenopausal women have an increased risk of breast cancer , cancer recurrence and death when compared with normal weight women . This higher risk could be due to an increased total body aromatization and subsequently elevated estrogen serum levels . 4 Aromatase inhibitors (AIs) are the gold standard of adjuvant hormonal therapy in hormone receptor-sensitive postmenopausal women with breast cancer, It can be given either as upfront or after 2-3 years of tamoxifen . 5 (AIs) block the aromatization of androgens to estrogens which occur in muscle and adipose tissue in postmenopausal women and thereby it depletes estrogen serum levels with subsequent improvement of disease-free survival and overall survival in the adjuvant as well as in the metastatic setting. 6,7 Obesity was found to have an impact on the effect of AIs ,specially Anastrozole, in patients with breast cancer. and it is not clear if the standard dose of anastrazole (1 mg) is sufficient to adequately suppress heightened aromatization related to obesity 8 .
Results from the 100-month follow-up analysis of the ATAC trial confirmed that women receiving 1 mg of Anastrazole with a high body mass index> 35 at baseline had a higher incidence of recurrences than those with a low BMI < 23. 9 BMI effect has been confirmed in the extended adjuvant setting in the ABCSG-6a trial and even in premenopausal women in an analysis of the ABCSG-12 trial. 10,11 Recent findings regarding the impact of obesity on the efficacy of adjuvant hormonal treatment with aromatase inhibitors (AIs) for early-stage breast cancer have added to the debate on whether obese women benefit less from AI treatment regarding disease-free survival and overall survival. 8 And it became mandatory to evaluate if the dosing of Anastrazole , Is (1 mg) insufficient to adequately suppress aromatization related to obesity?
The aim of this study was to assess the effect of obesity on estradiol depletion in postmenopausal women with hormonesensitive early breast cancer treated with Adjuvant upfront standard dose Anastrazole (1mg) after 6 months of treatment and its impact on survival.
Patients and Methods:-This prospective cohort study was conducted at the Clinical Oncology and Nuclear Medicine Department -Zagazig University Hospitals During the period of March 2013 to November 2016. The study included 100 postmenopausal women with hormonal receptors positive early breast cancer who received upfront Anastrazole 1mg/d . Informed consent was obtained from all cases before enrolment in the study ,All the data obtained from the patients were confidential and used only for research purposes.

Eligibility Criteria and pretreatment evaluation :-
The eligibility criteria included , postmenopausal women, Histologically confirmed early primary breast cancer who has positive hormone receptor status(ER and/or PR ) , ECOG performance scales of ≤ 2 , Patients who had completed initial therapy (i.e. surgical resection with or without adjuvant chemotherapy and radiation therapy), Patients started on adjuvant frontline hormonal treatment (Anastrazole 1 mg daily),no evidence of distant metastasis or local recurrence .
All the patients underwent pretreatment staging work up in the form of history and clinical examination ,complete blood picture (CBC), renal function test (RFT), and liver function tests (LFT) , Chest X-ray, pelvi abdominal ultrasound(US) and /or computed tomography(CT) scans and mammogram and US of contralateral breast. Brain CT or MRI and bone scan were done when indicated to exclude distant metastasis .
Treatment and follow up :-All eligible patients received Anastrazole as an adjuvant frontline treatment with standard dose of Anastrazole 1mg/day. Patients were classified according to BMI into two groups , non obese or normal weight (BMI<30kg/m 2 ) and obese (BMI>30kg/m 2 ) by using equation BMI=mass (kg)/ height (m 2 )according to the WHO (World Health Organization) and a baseline serum estradiol and FSH were obtained for each patient prior to starting Anastrazole therapy. Patients were followed up and serum estradiol and 2660 FSH were monitored again 6 months after starting Anastrazole 1 mg daily to detect any changes in their levels . Adverse effects of the treatment were monitored (hot flashes ,bone pain, depression, dyspnea, headache, anorexia, dry mouth, nausea, abdominal pain) at baseline and after 6 months of treatment .Toxicity was analyzed according to National Cancer Institute-Common Toxicity Criteria (CTC) criteria version2. 1998, patients underwent physical examination, and monitored every 3 months for: Local recurrences: (chest wall, ipsilateral breast and lymphatic's), new contra lateral breast cancer and distant metastasis.
The primary end point of the study was , detection of BMI variation and its relation to changes in serum Estradiol and FSH levels Secondary end point were to compare the OS, DFS and adverse events between the two groups.
Statistical analyses:-All statistical calculations were performed using the SPSS 19.0 and MedCalc windows. The normality of continues data were assessed using Kolmogorov test, they were normally distributed. To compare the demographics and tumor characteristics between obese and non-obese patients , Student's t-test, x 2 test or Fisher's exact test was used. To compare means of serum levels before and after AI treatment we used paired T test. Overall Survival (OS) was calculated as the time from diagnosis to death. Disease Free Survival (DFS) was calculated as the time from surgery to reappearance of disease local, regional or dist ant. Local Recurrence Free Survival (LRFS) was calculated as the time from surgery to local or regional reappearance of disease. Distant Metastasis Free Survival (DMFS) was calculated as the time from surgery to distant reappearance of disease. These timeto-event distributions were estimated using the method of Kaplan-Meier plot, and compared using two-sided exact log-rank test. A p-value ≤ 0.05 was considered significant.

Results:-
One hundred patients were included, half of them were classified being obese with (BMI≥30) with mean BMI(35±5.8) while the other half was considered non obese (BMI<30) mean BMI(24.5±4.4). Both groups were compared regarding patient measures and clinic pathologic characteristics , and both groups were comparable to each others as revealed in table (1).

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Comparing Estradiol and FSH levels in all patients before and 6 months after treatment:-On comparing Estradiol and FSH levels, we found that the mean estradiol serum level initially before the treatment was 19.45±4.1 pg ml −1 and then significantly reduced to 11.13 ±3.1 pg ml −1 6 months after treatment with AI (P =0.00) (Figure1) . On the other hand , inverse changes in FSH serum levels have occured as the mean FSH serum level initially was 70.91±20.7 mIU ml −1 and then significantly increased to 75.78±19.3 mIU ml −1 after 6 months of treatment with AI (P=0.00) (Figure 1, 2) .
Comparing Estradiol level between the studied groups before and 6 months after treatment:-At baseline, a slightly higher mean estradiol serum level was detected in obese compared with non-obese patients  Comparing Estradiol level between the studied groups 6 months after treatment however after 6 months of Anastrazole treatment , the mean ESL level was significantly higher in obese compared to non-obese patients (11.98±3.3 pg ml−1 VS 8.78±2.2 pg ml−1 ) (P <0.001) , and this difference reflected by significantly low serum FSH level in obese compared to non-obese patients(64.98±14.7 mIU ml−1 vs 87.53±17.6 mIU ml−1) (P <0.001) (Figure 3).

Survival analysis:
Relapsed (local recurrence and distant metastasis) was more in obese group than non obese ,it occurred in 5 patients (10%) and 4 patients (8%) in both groups respectively with non-significant difference between both groups (p=1.000) after three years of follow up .Furthermore ,died patients in obese group were higher than non obese ,5 patients (10%) versus 3 patients (6%) respectively with insignificant difference between both group (p=0.715) ( Table 3) .In addition, 3y DFS in non obese patients was 92% while it was 90% in obese patients with no significant difference between both groups (P=0.680) . 3y OS in non obese patients was 94% versus 90%in obese patients with insignificant difference between both groups (P=0.374) (Figure 4).

Discussion:-
Aromatase inhibitors (AIs) are the gold standard of adjuvant hormonal therapy in hormone receptor-sensitive postmenopausal women with breast cancer, It can be given either as upfront or switching after 2-3 years of tamoxifen .5 The Obesity increases the risk of breast cancer-specific mortality, 12,13,14 while maintaining a moderate weight may have a positive impact on breast cancer survival. 15 It is a well-known fact that obesity increases total-body aromatization which leads to increased serum estrogen level when compared with non-obese 10,16,17 . Obesity was found to have an impact on the effect of AIs ,specially Anastrazole, in patients with breast cancer. and it is not clear if the standard dose of anastrazole (1 mg) is sufficient to adequately suppress heightened aromatization related to obesity 8 .
In this study we assessed the effect of obesity on estradiol depletion in postmenopausal women with hormone-sensitive early breast cancer treated with Adjuvant upfront standard dose Anastrazole (1mg) after 6 months of treatment and its impact on survival .
The study included One hundred patients , half of them were classified being obese with (BMI≥30) with mean BMI ( 10 study ,as in ours, observed no statistically significant difference between the two groups as regard the toxicity but they stated that with caution due to the small number of patients in their trial which is the same limitation in our study. The results obtained from the ATAC trial confirmed lower efficacy of anastrozole treatment in women with obesity (BMI > 30) in terms of time to recurrence 7,9 . This is in accordance with the findings of Ewertz et al, who investigated the efficacy of AIs in correlation with weight and found a survival benefit for women with a BMI < 30 after 10 years of follow-up and no group differences were found for the first 10 years of follow-up. 18 Finally, Pfeiler et al(2011),observed a 60% relative increase in risk of disease recurrence as well as a 2-fold increase in the risk for death in patients with excess weight compared with those with normal weight who received anastrozole therapy in the ABCSG 12 trial 8 . The authors strongly suggested that incomplete estrogen serum level suppression through inadequate Anastrazole dosing explains these findings, and they assume an AI dose adjustment according to body weight is essential for the optimization of treatment efficacy. 19-20 Dose finding studies showed that low dosages of anastrozole (1 mg) was able to nearly fully block the aromatase and thereby lower estradiol serum levels to a minimum .However, these studies included small number of patients 23 .
Our preliminary results of survival analysis after three years of follow up were ,the relapse (local recurrence and distant metastasis) occurred more in obese group than non obese ,it occurred in 5 patients (10%) and 4 patients (8%) in both groups respectively with non-significant difference between both groups (p=1.000) .Furthermore ,died patients in obese group were higher than non obese ,5 patients (10%) versus 3 patients (6%) respectively with insignificant difference between both group (p=0.715) .In addition, 3y DFS in non obese patients was 92% while it was 90% in obese patients with no significant difference between both groups (P=0.680) .3y OS in non obese patients was 94% versus 90%in obese patients with insignificant difference between both groups (P=0.374) ,this is consistent with Ewertz et al trial, 18 who found no group differences between obese and non obese for the first 10 years of follow-up but a survival benefit for women with a BMI < 30 occurred after 10 years of follow-up and..Our explanation of insignificant survival results of our trial is , short follow up period which is one of limitations of our study but we are awaiting the final results after longer follow up period to see if there will be any significance be tween both groups regarding the outcome and survival or not. Furthermore , we recommend doing this study on larger number of patients with longer follow up period with addition of an important new point of research which is increasing the dose of Anastrazole according to BMI.