Differential effects of tamoxifen and anastrozole on optic cup size in breast cancer survivors

Ocular Side Effects of Aromatase Inhibitor Endocrine Therapy in Breast Cancer - A Review

BACKGROUND

Aromatase inhibitor therapy is currently the preferred choice in postmenopausal women with estrogen receptor positive breast cancer. This article reviews the ocular side effects of treatment with aromatase inhibitors (AIs) in patients with breast cancer.

MATERIALS AND METHODS

A comprehensive search was performed on PubMed, Web of Science and Google scholar.

RESULTS

After duplication removal, 14 clinical studies and 5 case reports, published between 2008 and 2021, were identified. Most frequently, AI treatment resulted in minor to moderate dry eye symptoms. "De novo" onset of Sjogren syndrome during AI therapy was also reported. Retinal and optic nerve side effects varied from mild, subclinical anatomic and functional impairment to severe decreased vision, secondary to hemi-central retinal artery occlusion, bilateral optic neuritis or uveitis with bilateral macular edema.

CONCLUSION

Visual disturbances encountered during AI treatment may be underestimated. Ophthalmic screening is important for early detection and appropriate treatment.

Prevalence of symptomatic dry eye in breast cancer patients undergoing systemic adjuvant treatment: A cross-sectional study

Objectives

To investigate the prevalence of symptomatic dry eye (SDE) on women undergoing systemic adjuvant therapy for breast cancer and its association with treatment settings.

Methods

Woman undergoing breast cancer systemic adjuvant therapy were included in exposure group. An age-matched non-treatment control group was recruited. This cross-sectional questionnaire-based study utilised validated Ocular Surface Disease Index (OSDI) and NCCN-FACT-Breast Cancer Symptom Index (NFBSI-16) questionnaires to determine the presence of SDE and investigate other breast cancer treatment complications. Additionally, demographic data and medical histories were collected.

Results

Of 423 eligible participants, 200 in each of the control group and the exposure group were included in the final analysis. The prevalence of SDE was 59.0% in breast cancer patients with adjuvant treatment, statistically significantly higher than 25.5% in the control group (P < 0.01). Additionally, exposure group experienced higher prevalence of moderate and severe SDE, which were 20.0% and 19.5% respectively compared with 9.0% and 4.0% in the control group (P = 0.002, P < 0.001). There was a significantly high prevalence of SDE among patients who had received over four cycles of systemic therapy (71.0%, P < 0.001) and the application of targeted therapy (71.2%, P = 0.014). The severity of SDE positively correlated with the cycles of treatment administered.

Conclusion

SDE was significantly predominant in women with breast cancer undergoing systemic adjuvant treatment. Our findings suggest dry eye assessments among patients receiving more than four cycles of chemotherapy or targeted therapy, thus early revealing possible dry eye conditions to both patients and clinicians for further specialized examination and treatment.

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Breast cancer patients undergoing systemic treatment have fairly high prevalence of symptomatic dry eye.

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Around 40% of them experienced from moderate to severe degree of dry eye.

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The severity of symptomatic dry eye in exposure group showed cycle-dependency.

The effects of adjuvant hormonotherapy on tear functions in patients with breast cancer

PURPOSE

Aromatase inhibitors (anastrozole, letrozole) and selective estrogen receptor modulators (tamoxifen) are widely used as adjuvant hormonal therapy in women with hormone receptor-positive breast cancer. We aimed to evaluate the effects of oral adjuvant hormonotherapy on tear functions in patients with breast cancer.

METHODS

In this case-control study, we enrolled eligible patients with breast cancer who were receiving regular medical selective estrogen receptor modulator (tamoxifen, n:50), aromatase inhibitors (anastrozole, letrozole, n:50) and gender-matched healthy controls (n:50). Tear functions were measured and compared by the Schirmer test, fluorescein breakup time, corneal staining evaluated by Oxford grading scale and Ocular Surface Disease Index scores.

RESULTS

Mean age was 49.95 (± 9.2), 51.52 (± 7.2) and 51.91 (± 10.3) in tamoxifen, aromatase inhibitors groups and controls (p = 0.426). Mean duration of BC diagnosis (p = 0.536) and drug use (p = 0.417) was not significant between two groups. Ocular Surface Disease Index scores were lower (p < 0.001), and fluorescein breakup time measurements were higher (p < 0.001) in controls. Schirmer test scores were higher in controls than aromatase inhibitors group (p < 0.001). According to the scores of all measurements, the differences between aromatase inhibitors and tamoxifen groups were statistically significant (p < 0.001).

CONCLUSIONS

Our results demonstrated a high difference in all parameters in patients receiving aromatase inhibitors compared to tamoxifen group and controls. Aromatase inhibitors, which reduce estrogen levels in the blood, might affect the tear functions more than tamoxifen, which affects as antiestrogenic on estrogen receptors.

The Effects of Adjuvant Tamoxifen Use on Macula Pigment Epithelium Optical Density, Visual Acuity and Retinal Thickness in Patients with Breast Cancer

Purpose: We aimed to compare best corrected visual acuity, macular pigment optical density and macular thickness in patients with breast cancer, who received oral adjuvant hormone therapy.Materials and Methods: We enrolled consecutive eligible patients with breast cancer who were receiving regular medical tamoxifen treatment. The participants were divided into two groups as cases and controls. Best-corrected visual acuity and retinal thickness were examined. Macular pigment optical density was measured by fundus reflectometry using the one-wavelength reflection method. The output parameters included max optical density, mean optical density, volume and area of the right eye.Results: A total of 104 eyes, cases (n: 50) and controls (n: 54) were included in the study. Mean age in cases was 49.95 ± 9.2 years and 50.21 ± 9.3 years in controls (p = .151). The mean foveal optical density and the maximum optical density differed between cases (0.13 ± 0.03 density units (DU)/0.35 ± 0.07 DU) and controls (0.18 ± 0.04 DU/0.41 ± 0.06 DU) (p = .002/p = .009). Macular pigment optical density volume was 8102.84 ± 2412.67 in cases versus 8280.18 ± 2904.56 in controls (p = .034), and mean MPOD area was 59567.79 ± 11538.06 in cases versus 61748.14 ± 10591.19 in controls (p = .023). The best corrected visual acuity and retinal thickness were similar in both groups (p > .05).Conclusions: Patients in care of oral tamoxifen therapy were found to have significantly reduced macular pigment optical density. In addition, higher drug use duration correlated significantly with reduced macular pigment optical density, suggesting that the poor long-term effects may play a role in macular pigment absorption and incorporation in the retinal tissue.

Electroretinographic and optical coherence tomography findings in breast cancer patients using aromatase inhibitors

BACKGROUND

The present cross-sectional study has the purpose to investigate the impact of aromatase inhibitors (AIs) on retinal nerve fiber layer (RNFL) thickness, optic nerve and macular function in patients using AIs for breast cancer treatment.

METHODS

Participants in our study were 41 hormone-receptor-positive earlystage breast cancer patients who were treated with AIs in the adjuvant setting. Moreover, 40 age- and gender-matched control subjects, having neither ocular nor systemic disorders, were included in this study. All participants underwent a complete ophthalmological examination, including best corrected visual acuity (BCVA) assessment, RNFL thickness and central foveal thickness (CFT) measurement, visual evoked potentials (VEP) recording and multifocal-electroretinogram (mf-ERG) recording. Univariate and multiple regression analyses were performed.

RESULTS

At the multiple regression analyses, patients receiving AIs presented with lower average RNFL and inferior RNFL. Moreover, similarly to the univariate analysis, intake of AIs was associated with lower amplitude P100, lower retinal response density in ring 1 and ring 2, longer peak time P100 and longer P1 time in ring 1.

CONCLUSION

Our study is the first in the literature investigating the potential effect of AIs on RNFL thickness, optic nerve and macular function in patients using AIs for breast cancer treatment. The principal message of our study is that patients using AIs exhibited a significant decrease in RNFL thickness (average, superior and inferior), retinal response density and visual acuity compared to healthy controls, while VEP findings (both amplitude and peak time of P100) differ significantly as well.

Oestrogen, ocular function and low-level vision: a review

Over the past 10 years, a literature has emerged concerning the sex steroid hormone oestrogen and its role in human vision. Herein, we review evidence that oestrogen (oestradiol) levels may significantly affect ocular function and low-level vision, particularly in older females. In doing so, we have examined a number of vision-related disorders including dry eye, cataract, increased intraocular pressure, glaucoma, age-related macular degeneration and Leber's hereditary optic neuropathy. In each case, we have found oestrogen, or lack thereof, to have a role. We have also included discussion of how oestrogen-related pharmacological treatments for menopause and breast cancer can impact the pathology of the eye and a number of psychophysical aspects of vision. Finally, we have reviewed oestrogen's pharmacology and suggest potential mechanisms underlying its beneficial effects, with particular emphasis on anti-apoptotic and vascular effects.

Bilateral Optic Disc Swelling Following Anastrozole Therapy

A 56-year-old female with early-stage breast cancer, stage IA grade 1 endometrial cancer, and stage IC grade 1 ovarian cancer developed sudden-onset visual changes and right inferior visual field defect following anastrozole therapy. Examination revealed severe bilateral optic disc swelling and impaired visual acuity. Laboratory work-up was otherwise unremarkable. Anastrozole was discontinued and over the next month, patient had near-complete resolution of swelling in the right eye and improvement in the left eye. This is the only reported case of optic disc swelling following anastrozole therapy.

Ocular side effects of biological agents in oncology: what should the clinician be aware of?

During the last 20 years, biologicals have become increasingly relevant in oncologic therapy. Depending on the medication used, there are different profiles of ocular side effects. Although these can be present in up to 70% of patients, they are generally underreported in the literature. Therefore, the pathophysiological details of their development are often poorly understood. Herein we attempt to identify groups of biologicals to which a specific side effect profile can be assigned. We also tried to capture all relevant side effects and therefore conducted several database investigation including Medline, Cochrane library, and the drugs section of the US Food and Drug Administration (FDA), using the following search strings: “name of biological agent (both generic and commercial names)” AND “eye” OR “ocular”. If we found a side effect that has been associated with a drug, we researched Medline using the following search string: “name of biological agent” (both generic and commercial names) AND “term for the specific side effect”. Due to the wealth of material we report only the drugs that are approved by the FDA.

Dry eye syndrome in aromatase inhibitor users

BACKGROUND

Aromatase inhibitors are frequently used as an adjuvant therapy in the treatment of breast cancer. We observed that several patients taking aromatase inhibitors presented with severe dry eye symptoms, and we investigated whether there is a relationship between aromatase inhibitors and dry eyes in these patients.

DESIGN

Retrospective chart review.

PARTICIPANTS

Forty-one women.

METHODS

A computerized search of health records was performed to identify patients using anastrazole, letrozole and exemestane seen by the Cornea Service from August 2008 to March 2011. The results were compared with age-matched controls.

MAIN OUTCOME MEASURES

Ocular surface changes among aromatase inhibitors users.

RESULTS

Of the 41 women, 39 were Caucasians. Thirty-nine patients had breast cancer (95%), one patient had ovarian cancer (2.5%) and one had an unknown primary cancer. Mean age was 68 ± 11.3 years (range 47-95). Most common presenting symptoms were blurred vision in 28 (68%) patients, irritation/foreign body sensation in 12 (29%) patients, redness in 9 (22%) patients, tearing in 6 (22%) patients and photosensitivity in 2 (5%) patients. Mean Schirmer's test measurement was 11 ± 5.8 mm (range 0.5-20 mm). Blepharitis was noted in 68 of 82 eyes (73%), decreased or poor tear function in 24 eyes (29%), conjunctival injection in 18 eyes (22%) and superficial punctate keratitis in 12 eyes (29%). Among an age-matched population (45-95 years), dry eye syndrome was found in only 9.5% of patients.

CONCLUSIONS

Because the prevalence of ocular surface disease signs and symptoms appears to be higher in study group than control patients, aromatase inhibitors might be a contributing factor to the dry eye symptoms.

Ocular Toxicity of Targeted Therapies

Molecularly targeted agents are commonly used in oncology practice, and many new targeted agents are currently being tested in clinical trials. Although these agents are thought to be more specific and less toxic then traditional cytotoxic chemotherapy, they are associated with a variety of toxicities, including ocular toxicity. Many of the molecules targeted by anticancer agents are also expressed in ocular tissues. We reviewed the literature for described ocular toxicities associated with both approved and investigational molecularly targeted agents. Ocular toxicity has been described with numerous approved targeted agents and also seems to be associated with several classes of agents currently being tested in early-phase clinical trials. We discuss the proposed pathogenesis, monitoring guidelines, and management recommendations. It is important for oncologists to be aware of the potential for ocular toxicity, with prompt recognition of symptoms that require referral to an ophthalmologist. Ongoing collaboration between oncologists and ocular disease specialists is critical as the use of molecularly targeted agents continues to expand and novel targeted drug combinations are developed.

Breast cancer medications and vision: effects of treatments for early-stage disease

This review concerns the effects on vision and the eye of medications prescribed at three phases of treatment for women with early-stage breast cancer (BC): (1) adjuvant cytotoxic chemotherapy, (2) adjuvant endocrine therapy, and (3) symptomatic relief. The most common side effects of cytotoxic chemotherapy are epiphora and ocular surface irritation, which can be caused by any of several different regimens. Most notably, the taxane docetaxel can lead to epiphora by inducing canalicular stenosis. The selective-estrogen-receptor-modulator (SERM) tamoxifen, long the gold-standard adjuvant-endocrine-therapy for women with hormone-receptor-positive BC, increases the risk of posterior subcapsular cataract. Tamoxifen also affects the optic nerve head more often than previously thought, apparently by causing subclinical swelling within the first 2 years of use for women older than ∼50 years. Tamoxifen retinopathy is rare, but it can cause foveal cystoid spaces that are revealed with spectral-domain optical coherence tomography (OCT) and that may increase the risk for macular holes. Tamoxifen often alters the perceived color of flashed lights detected via short-wavelength-sensitive (SWS) cone response isolated psychophysically; these altered perceptions may reflect a neural-response sluggishness that becomes evident at ∼2 years of use. The aromatase inhibitor (AI) anastrozole affects perception similarly, but in an age-dependent manner suggesting that the change of estrogen activity towards lower levels is more important than the low estrogen activity itself. Based on analysis of OCT retinal thickness data, it is likely that anastrozole increases the tractional force between the vitreous and retina. Consequently, AI users, myopic AI users particularly, might be at increased risk for traction-related vision loss. Because bisphosphonates are sometimes prescribed to redress AI-induced bone loss, clinicians should be aware of their potential to cause scleritis and uveitis occasionally. We conclude by suggesting some avenues for future research into the visual and ocular effects of AIs, particularly as relates to assessment of cognitive function.

Variability in short-wavelength automated perimetry among peri- or postmenopausal women: a dependence on phyto-oestrogen consumption?

PURPOSE

To determine whether the hill of vision for Short-Wavelength Automated Perimetry (SWAP) is shallower for women who consume phyto-oestrogen-rich foods than for women who do not.

METHODS

Visual field data were compared for two groups of healthy amenorrhoeic women 48-69 years-old with normal vision and not using hormone replacement: (1) 24 subjects who reported consuming soy and/or flax products and (2) 20 subjects who reported not consuming these products. Two types of 24-2 visual fields were measured: (1) Full Threshold SWAP and (2) a white-on-white (W/W) field obtained using a Swedish Interactive Threshold Algorithm (SITA Standard).

RESULTS

The reduction of SWAP sensitivity from the centre of the field (4 loci, mean eccentricity = 4.2°) to the periphery (20 loci, mean eccentricity = 21.9°) was less for soy/flax consumers than for nonconsumers, both with age-referencing (mean difference = 1.7 dB, p = 0.018) and without (p = 0.012). Corresponding distinctions existed for the SWAP - W/W difference, and there was minimal effect for W/W fields alone. The peripheral age-referenced SWAP sensitivities averaged 2.5 dB higher for consumers than nonconsumers (p = 0.022).

CONCLUSION

The between-group distinctions are consistent with the possibility (derived from the women's health literature) that phyto-oestrogens may counteract a decline of short-wavelength-sensitive cone-mediated response among postmenopausal women. These results suggest another potential application for SWAP outside its original intended purpose as a glaucoma test. Future studies should assess whether phyto-oestrogen consumption is most beneficial for women who are sufficiently young and/or not too far beyond menopause.

Identifying factors associated with falls in postmenopausal breast cancer survivors: a multi-disciplinary approach

OBJECTIVE

To identify neuromuscular, balance, and vision factors that contribute to falls in recently treated breast cancer survivors (BCS) and explore links between fall risk factors and cancer treatment.

DESIGN

Case-control plus prospective observation.

SETTING

Comprehensive cancer center.

PARTICIPANTS

BCS (N=59; mean age, 58y) within 2 years of chemotherapy completion and/or on adjuvant endocrine therapy.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Objective measures of postural control, vision, and neuromuscular function included: (1) a sensory organization test (SOT), (2) a visual assessment battery, (3) muscle mass by dual energy x-ray absorptiometry, and (4) neuromuscular function with strength by repetition maximum, power by timed stair climb, and gait speed by 4m walk. Falls were self-reported for the past year (retrospective) and monthly for 6 months (prospective).

RESULTS

Fifty eight percent of BCS reported falls in the past year. BCS with a history of falls had lower SOT scores with a vestibular deficit pattern in postural control (P<.01) and took longer to read letters on the contrast sensitivity chart (P<.05). Vestibular score on the SOT mediated the relationship between treatment and falls among BCS who received chemotherapy only, but not adjuvant endocrine therapy.

CONCLUSIONS

Results of this project suggest that balance disturbances of vestibular origin and delays in detecting low contrast visual stimuli are associated with falls in BCS. Future studies that track falls and fall risk factors in BCS from diagnosis through treatment are warranted, as are studies that can identify treatment-related vestibular dysfunction and altered visual processing.

A review of exercise interventions to improve bone health in adult cancer survivors

INTRODUCTION

Cancer-treatment induced bone loss and associated fracture risk is a growing concern for cancer survivors. Exercise offers a non-pharmacologic strategy for preserving bone health during and after treatment, but only until recently has it been studied for its efficacy and safety in cancer survivors. The purpose of this review is to provide an early qualitative evaluation of exercise trials in adult cancer survivors with bone health as a primary or secondary endpoint.

METHODS

Databases were searched for exercise trials in adult cancer survivors that reported data on bone health (bone mineral density (BMD) and/or bone remodeling markers) as an outcome measure and were published and indexed prior to January 1st, 2010. Data relevant to evaluation of study design, sample, exercise protocol, bone health assessment, statistical approach and findings were extracted, summarized and interpreted.

RESULTS

Eight trials were identified that met criteria for inclusion in the review. While most studies were conducted in breast cancer survivors, remaining study attributes including rigor, design, exercise program characteristics and length varied considerably across studies. Only three of the eight studies were controlled exercise trials with usual care control groups. Of these, two reported significant group x time interactions where aerobic exercise preserved BMD at the spine or whole body compared to losses in controls and none reported exercise benefits at the hip.

CONCLUSIONS

The recent emergence of exercise studies in cancer survivors with bone outcomes highlights the importance of this area of cancer survivorship. Collectively, the studies are limited in number and are too varied to warrant conclusions regarding the skeletal benefits of exercise during or after cancer treatment, though early results are encouraging and more rigorous study should follow.

Vitreo-retinal traction and anastrozole use

PURPOSE

This study tested a prediction stemming from the hypothesis that anastrozole users experience heightened vitreo-retinal traction. This hypothesis was based on the knowledge that menopause increases the risk of intraocular tractional events such as posterior vitreous detachments (PVDs).

METHODS

Retinal thickness was measured for 3 groups of amenorrheic women: (1) anastrozole users and (2) tamoxifen users undergoing adjuvant therapy for early-stage breast cancer, and (3) control subjects not using hormonal medication. Foveal shape indices were derived for subjects without PVDs.

RESULTS

For anastrozole users, the distance to the temporal side of the fovea became less than the distance to the nasal side at a sufficient height above the foveal base. This effect did not exist for control subjects; the between-group difference was appreciable. Results concerning tamoxifen users were inconclusive.

CONCLUSIONS

The foveas of women using anastrozole appear to be subjected to more tractional force than are the foveas of women not using any hormonal medication.

Retinal hemorrhages in anastrozole users

PURPOSE

To determine whether women using anastrozole (an aromatase inhibitor, which suppresses estrogen synthesis) are likely to have retinal hemorrhages.

METHODS

Fundus photographs were obtained for a study comparing effects on vision and the eye of anastrozole (1 mg/d) and tamoxifen (20 mg/d) for women receiving adjuvant endocrine therapy for early-stage breast cancer. Photographs (2 eyes per subject) were evaluated for hemorrhages by an ophthalmologist masked from identifying subject information. The presence of hemorrhages was assessed for 35 anastrozole users, 38 amenorrheic tamoxifen users, and 53 amenorrheic (peri- or postmenopausal) control subjects not using any endocrine medication. The age range was 43 to 69 years; only subjects reporting normal vision and healthy eyes were recruited. Photographs from 36 tamoxifen users from a previous study also were assessed. Views of the fundus extended appreciably beyond the posterior pole for all tamoxifen and anastrozole users, and for 38 of the control subjects. Photographic assessments were compared with medical history and blood pressure data, and optical coherence tomography was used for quantifying aspects of foveal shape that might be affected by vitreoretinal traction.

RESULTS

Four anastrozole users and no contemporaneous tamoxifen users but one previously tested tamoxifen user had retinal hemorrhages, in each case within the posterior pole. Two anastrozole users had a flame hemorrhage (in the retinal nerve fiber layer), and two had a blot hemorrhage (deeper in the retina). No control subjects were observed to have hemorrhages.

CONCLUSIONS

Anastrozole use appears to be associated with an increased prevalence of retinal hemorrhages. The hemorrhages may mark systemic vascular compromise resulting from estrogen depletion, and/or they may be consequences of vitreoretinal traction resulting from estrogen depletion. They may also depend on the use of medications for controlling common anastrozole-induced side effects. Prospective studies need to be conducted with larger numbers of subjects.

The color appearance of stimuli detected via short-wavelength-sensitive cones: comparisons with visual adaptation and visual field data for peri- or post-menopausal women under 70 years of age

Dynamics of foveal light adaptation for vision mediated via short-wavelength-sensitive (SWS) cones were compared for two groups of healthy amenorrheic (peri- or post-menopausal) women not using hormonal medication. Each subject was assigned to a group based on the color name-"lavender" ( approximately 2/3 of all subjects) or "white" (approximately 1/3 of all subjects)-chosen in a forced-response paradigm to best describe a threshold-level 440-nm test presented on a larger 3.6 log td 580-nm background that had been viewed for approximately 5 min. During the first 20-30s after this 3.6 log td background abruptly replaced a much dimmer background, the threshold elevations (relative to the steady-state levels measured at approximately 5 min) were significantly greater for the lavender-naming subjects than for the white-naming subjects. However, exponential rates of recovery were indistinguishable for the two groups. A viable interpretation is that the gain of the visual response at background onset is greater for lavender-naming subjects than for white-naming subjects at or distal to a site where responses from middle-wavelength-sensitive and long-wavelength-sensitive (MWS and LWS) cones oppose responses from SWS cones. In addition, the color names derived from foveal testing were related systematically to extrafoveal sensitivities measured with Short Wavelength Automated Perimetry (SWAP), in a manner suggesting that response gain and/or response speed may be greater for lavender-naming subjects in the direction of increased SWS response also. Evidence from other subject populations suggests that the choice of color name and the dynamics of visual response each can be affected by alterations (particularly reductions) of estrogen synthesis and response.

Endogenous hormones, participant characteristics, and symptoms among midlife women

OBJECTIVES

The primary aim of this study was to examine the associations between endogenous hormone levels and symptoms other than hot flashes in a sample of midlife women.

METHODS

Data from a community-based sample of 603 women aged 45-54 years who had never used hormone therapy were analyzed. Each participant completed a questionnaire to obtain data on demographic and lifestyle characteristics as well as symptoms, including headache, insomnia, vision problems, vaginal discharge and dryness, irritability, and incontinence. In addition, each participant provided a blood sample that was used to measure estrogen, androgen, and sex hormone binding globulin (SHBG) concentrations by enzyme-linked immunosorbent assay.

RESULTS

Prevalence rates of symptoms ranged from 51.4% (irritability) to 18.6% (vision problems). In adjusted analyses, the free estradiol index (FEI) was significantly and positively associated with the reporting of insomnia (odds ratio (OR) 1.28; 95% confidence interval (CI) 1.01-1.61). Further, higher SHBG levels were significantly associated with lower odds of reporting vision problems (OR 0.44; 95% CI 0.23-0.81).

CONCLUSIONS

This study provides evidence that hormones are associated with insomnia and visual problems during midlife. However, some of these results conflict with previous findings. Given the overall paucity of literature on these issues, more investigation is warranted.