The advantage of letrozole over tamoxifen in the BIG 1-98 trial is consistent in younger postmenopausal women and in those with chemotherapy-induced menopause

Adjuvant Aromatase Inhibitors or Tamoxifen following Chemotherapy for Perimenopausal Breast Cancer Patients

Background

The benefit of adjuvant aromatase inhibitors (AI) vs tamoxifen has been investigated in randomized clinical trials for premenopausal and postmenopausal patients with early, estrogen receptor–positive (ER+) breast cancer. The optimal endocrine treatment for chemotherapy-treated perimenopausal women, who generally develop chemotherapy-induced amenorrhea, is uncertain.

Methods

All Dutch women who received adjuvant chemotherapy and endocrine treatment for stage I-III, ER+ (>10% positive cells), invasive breast cancer diagnosed between 2004 and 2007 were identified through the Netherlands Cancer Registry. Included women were considered perimenopausal based on an age at diagnosis of 45 to 50 years (n = 2295). For each patient, AI treatment duration relative to total endocrine treatment duration was calculated. Predominantly tamoxifen-treated patients (AI < 25%) were compared with those receiving AI and tamoxifen for a similar duration (AI 25%-75%) and those mostly using AI (AI > 75%). Adjusted hazard ratios (HRs) for recurrence-free survival (RFS) and overall survival were calculated using time-dependent Cox regression.

Results

After an average follow-up of 7.6 years, 377 RFS events occurred. Women mostly receiving AI (AI > 75%) had the best RFS (adjusted HR = 0.63, 95% confidence interval = 0.46 to 0.86) followed by those receiving AI 25% to 75% (adjusted HR = 0.85, 95% confidence interval = 0.65 to 1.12) compared with predominantly tamoxifen-treated women. Trend analyses showed that every 10% increase in AI-endocrine treatment ratio reduced RFS event risk by 5% (2-sided P_trend = .002). In total, 236 deaths occurred; hazard ratios for overall survival showed similar trends.

Conclusions

These results suggest that the best adjuvant endocrine treatment for chemotherapy-treated, ER+ breast cancer patients diagnosed aged 45-50 years consists of mainly AI followed by a switch strategy and mainly tamoxifen.

Incidence and Predictive Factors for Recovery of Ovarian Function in Amenorrheic Women in Their 40s Treated With Letrozole

PURPOSE

This prospective study assessed the impact of 2 years of aromatase inhibitor (AI) therapy on the incidence of ovarian function recovery (OFR) in women age 40 to 49 with estrogen receptor-positive breast cancer who were premenopausal at diagnosis and who underwent chemotherapy-induced amenorrhea during adjuvant treatment.

PATIENTS AND METHODS

Women age 40 to 49 with estrogen receptor-positive breast cancer who had ceased menstruating with adjuvant cyclophosphamide-based chemotherapy, had postmenopausal serum estradiol (E2), and had received tamoxifen for ≥ 1 year were treated with letrozole (2.5 mg) daily for ≥ 2 years. Serum follicle-stimulating hormone (FSH) and E2 were measured at baseline and over 2 years. A general linear model was used to assess serial FSH by OFR. Logistic regression was used to assess baseline predictors and OFR.

RESULTS

The study enrolled 177 women (145 women age 45 to 49 years and 32 women age 40 to 44 years). Of 173 evaluable patients, 67 (39%; 95% CI, 31% to 46%) regained ovarian function; 11 of these patients (6%; 95% CI, 3% to 10%) resumed menses, and 56 of these patients (32%; 95% CI, 25% to 39%) developed premenopausal E2 without menses. Among AI-naïve patients, serial FSH significantly increased over time (P < .001), did not vary significantly by OFR status (P = .55), but showed mild evidence of a decrease after month 12 for those who resumed menses (P = .0989). Age less than 45 years and inhibin B were significant multivariable baseline predictors of OFR.

CONCLUSION

These results emphasize the challenge in determining definitive menopause in women with chemotherapy-induced amenorrhea. The risk of OFR during treatment with AIs in amenorrheic women in their 40s is high, and AI therapy should be avoided in these patients.

Adjuvant endocrine therapy in premenopausal women with breast cancer

Breast cancer remains the leading cause of cancer-related mortality in premenopausal women. Multiple advances in local and systemic therapies have dramatically improved outcomes in women with hormone receptor-positive early-stage breast cancer. Despite these advances, early and late relapses occur. Therefore, multiple adjuvant endocrine therapy trials have been conducted with the goal of decreasing breast cancer recurrence and mortality. Recently, large international trials evaluating extended endocrine therapy and ovarian suppression with and without tamoxifen or exemestane have been reported. These studies add to the large body of existing data on adjuvant endocrine therapy in premenopausal women with breast cancer and provide additional therapeutic options in those at high risk of disease recurrence. This review will synthesize the most recent data and promote an evidence-based approach, highlighting quality-of-life concerns, to considering adjuvant endocrine therapies in premenopausal women.

The renaissance of endocrine therapy in breast cancer

PURPOSE OF REVIEW

Endocrine therapy for breast cancer has been the cornerstone of treatment for over a century since the discovery of the regressive effect of oophorectomy on 'cancer of the mamma' in 1896 by Beatson. Studies in the prevention and treatment of both early and metastatic breast cancer will be reviewed with a focus on recent large randomized clinical trials that may be practice changing.

RECENT FINDINGS

Data from pivotal clinical trials that looked at the duration of adjuvant tamoxifen therapy in premenopausal women will be discussed. In addition, several recent clinical trials that address the optimal sequence of endocrine therapy and advances in the treatment of endocrine-resistant metastatic disease will be reviewed. New findings from molecular studies that demonstrate targets in the endocrine axis and the role of aromatase inhibitors in the prevention setting will be highlighted.

SUMMARY

Overall, these clinical trials show the benefit of aromatase inhibitors in the prevention setting, longer duration of tamoxifen in the adjuvant setting for premenopausal women, and new biologic agents with hormonal therapies.