Abstract P3-08-18: Association of tamoxifen use and ovarian aging in patients with invasive or pre-invasive breast cancer

Background: The use of tamoxifen has been shown to delay the recovery of chemotherapy-induced amenorrhea, however the independent impact of long-term endocrine therapy on ovarian aging is not known, and to our knowledge, has never been directly investigated. Understanding the effect of endocrine therapy on ovarian aging will help breast cancer patients of reproductive age make more informed and empowered decisions regarding their treatment. The aim of this study is to explore the relationship between tamoxifen therapy and age onset of menopause.

Methods: We conducted a retrospective cohort study using patients identified through the UCSF Cancer Registry and UCSF SPORE database. Women who were diagnosed with Stage 1-3 invasive or in situ breast cancer between 1985 and 2011, who were premenopausal at the time of diagnosis and who did not receive systemic chemotherapy were included. Patients with recurrent disease and prior ovarian surgery were excluded. Eligibility was confirmed by telephone, and online or paper surveys were distributed to eligible subjects only. Age onset of menopause was the primary endpoint of the study and was defined as the age at which a woman had her last period and no menses for 12 months. Age onset of menopause was assessed through surveys. The primary analysis compared age onset of menopause between subjects who received tamoxifen for any duration and control subjects who never received tamoxifen. Secondary analyses were performed using a Cox proportional hazards model to determine whether duration of tamoxifen exposure and age of tamoxifen initiation impacted age onset of menopause in subjects treated with tamoxifen.

Results: A total of 1137 potential subjects believed to meet eligibility criteria were identified and called, and 649 subjects were reached. Eligibility was confirmed by phone in 340 subjects. A total of 336 subjects consented to participate in the study, and 262 (78%) completed and returned the survey. 227 subjects were included in the primary analysis of which 110 subjects received prior tamoxifen, and 117 subjects received no prior tamoxifen. At the time of the survey, 16.3% vs. 20.2% of patients under age 50 that were exposed and not exposed to tamoxifen entered menopause, respectively. The median age onset of menopause was 50.94 and 51.34 for the tamoxifen and no tamoxifen groups, respectively. The hazard ratio between these groups was 1.077 which was not statistically significant (p = 0.6917). No association (p = 0.55) was found between the duration of tamoxifen use and the age onset of menopause. When controlling for tamoxifen duration, there was no significant difference (p = 0.93) in age onset of menopause between subjects who initiated tamoxifen prior to age 45 and those who initiated at age 45 or older.

Conclusion: These data suggest that tamoxifen alone is not associated with an earlier age onset of menopause, and that tamoxifen use, in the absence of systemic chemotherapy, is unlikely to significantly accelerate ovarian aging.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-08-18.

Abstract P2-02-04: Kinetic heterogeneity features on breast DCE-MRI as prognostic markers of breast cancer recurrence

PURPOSE

Breast tumors have been shown to be heterogeneous lesions, and tumor heterogeneity is one of the major difficulties in the way of an effective cancer diagnosis and successful treatment. We evaluate the predictive capacity of DCE-MRI kinetic heterogeneity features for assessing the risk of breast cancer recurrence as determined by a validated tumor gene expression assay.

METHOD AND MATERIALS

Bilateral Breast DCE-MRI scans were retrospectively analyzed from 57 women with estrogen receptor positive/node negative invasive breast cancer. The ages of the women at the time of the imaging ranged from 37 to 74 years with a mean age of 55.5 years. The women were imaged prone in a 1.5T scanner (GE LX echo, GE Healthcare, or Siemens Sonata, Siemens); matrix size: 512 × 512; slice thickness: 2.4-4.4 mm; flip angle: 25° or 30°. The images were collected before and after the administration of gadodiamide (Omniscan) or gadobenate dimeglumine (MultiHance) contrast agents. Dynamic contrast enhanced images were acquired at 90 second intervals for 3 post contrast time points. The women had previously undergone Oncotype Dx (Genomic Health Inc.) profiling of their tumor. The Oncotype DX assay provides the likelihood of 10-year breast cancer recurrence, using a score stratified into 3 risk categories (risk: low ≤17, medium = 18-30, high ≥ 31). Pixel-wise relative enhancement curves were computed using three post-contrast time points. Fuzzy C-means clustering was applied to partition the tumor pixels according to the variance of their relative enhancement. To capture kinetic heterogeneity, wavelet features were extracted within each tumor partition as a measure of spatial variation. Mean and variance of these features were further estimated within each region. Using these features, multivariable logistic regression was performed with leave-one-out cross-validation and feature selection to classify the tumors as high or low/medium risk. We compared our kinetic heterogeneity features against standard kinetics and texture features. Area under the curve (AUC) of the receiver operating characteristic (ROC) was used to evaluate classification performance.

RESULTS

Feature selection indicated an optimal set of 7 kinetic heterogeneity features (out of 54). The classifier based on these features had an AUC = 0.82 in classifying high versus low/medium risk tumors. Classifiers based on standard kinetics and texture features performed with AUCs of 0.69 and 0.64 respectively.

CONCLUSION

Wavelet kinetic features from breast DCE-MRI could be used to capture the spatial pattern of kinetic heterogeneity of and potentially serve as prognostic markers for the risk of recurrence. In addition, breast DCE-MRI kinetic heterogeneity features could be used to assess likelihood of recurrence and ultimately help guide therapeutic decisions. Larger studies are needed to validate these findings.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-02-04.