Oncology Advanced Practitioners and Breast Cancer Prevention

One in eight American women will be diagnosed with breast cancer. Advanced practitioners in oncology can offer risk assessments, counseling, genetic testing, and make both behavioral and pharmacologic recommendations for breast cancer risk reduction. The role of oncology advanced practitioners in conjunction with genetic counselors is key in what is now considered the standard of care. This article will summarize the current state of breast cancer prevention and the role of oncology advanced practitioners.

Clinical and genetic risk factors for aromatase inhibitor-associated arthralgia in breast cancer survivors

BACKGROUND

Arthralgia is a common and debilitating toxicity of aromatase inhibitors (AI) that leads to premature drug discontinuation. We sought to evaluate the clinical and genetic risk factors associated with AI-associated arthralgia (AIAA).

METHODS

We performed a cross-sectional study among postmenopausal women with stage 0-III breast cancer who were prescribed a third-generation AI for adjuvant therapy. The primary outcome was patient-reported AIAA occurrence. We extracted and assayed germline DNA for single nucleotide polymorphisms (SNPs) of genes implicated in estrogen and inflammation pathways. Multivariable logistic regression models examined the association between demographic, clinical, and genetic factors and AIAA. Analyses were restricted to White participants.

RESULTS

Among 1049 White participants, 543 (52%) reported AIAA. In multivariable analyses, women who had a college education [Adjusted Odds Ratio (AOR) 1.49, 95% Confidence Interval (CI) 1.00-2.20], had a more recent transition into menopause (<10 years) (5-10 years AOR 1.55, 95% CI 1.09-2.22; <5 years AOR 1.78, 95% CI 1.18-2.67), were within one year of starting AIs (AOR 1.61, 95% CI 1.08-2.40), and those who received chemotherapy (AOR 1.38, 95% CI 1.02-1.88) were significantly more likely to report AIAA. Additionally, SNP rs11648233 (HSD17B2) was significantly associated with higher odds of AIAA (AOR 2.21, 95% CI 1.55-3.16).

CONCLUSIONS

Time since menopause and start of AIs, prior chemotherapy, and SNP rs11648233 within the HSD17B2 gene in the estrogen pathway were significantly associated with patient-reported AIAA. These findings suggest that clinical and genetic factors involved in estrogen withdrawal increase the risk of AIAA in postmenopausal breast cancer survivors.

Prevalence and risk factors for fatigue among breast cancer survivors on aromatase inhibitors

PURPOSE

Fatigue is the most common and distressing symptom experienced by cancer survivors. This study sought to determine the prevalence and risk factors for fatigue among breast cancer (BC) survivors receiving aromatase inhibitors (AIs).

MATERIAL AND METHODS

We conducted a cross-sectional survey study among postmenopausal women with stage 0 to III BC receiving adjuvant AI therapy at the outpatient breast oncology clinic of a large university hospital. Participants with a score ≥4 on the 'worst fatigue' item of the Brief Fatigue Inventory were classified as having moderate or severe fatigue. Multivariate logistic regression analyses were performed to evaluate risk factors.

RESULTS

Among 1103 participants, 616 (55.8%) had moderate or severe fatigue. In the multivariate logistic regression model, women younger than 55 years were significantly more likely to report moderate to severe fatigue than women older than 65 years (adjusted odds ratio [AOR] = 1.58, 95% confidence interval [CI] = 1.07-2.35; p = 0.023). Compared to women with high school or less education, women with college or more education were significantly more likely to report moderate to severe fatigue (AOR = 1.40, 95% CI = 1.02-1.91; p = 0.037). Increasing body mass index (BMI) was significantly associated with increased risk of experiencing moderate to severe fatigue (overweight: AOR = 1.37, 95% CI = 1.01-1.84, p = 0.042; obesity: AOR = 2.08, 95% CI = 1.53-2.81, p < 0.001). Fatigue was significantly correlated with pain severity (r = 0.48, p < 0.001) and insomnia (r = 0.62, p < 0.001).

CONCLUSION

Moderate to severe fatigue complaints exceed 50% among AI users. Fatigue is highly related to younger age, higher education level, higher BMI, pain severity and insomnia.

The implications of genetic variation for the pharmacokinetics and pharmacodynamics of aromatase inhibitors

INTRODUCTION

Breast cancer is the most common female cancer and remains a serious public health concern worldwide. Third-generation aromatase inhibitors (AIs) are widely used in postmenopausal women with estrogen receptor positive breast cancer. However, there is marked interindividual variability in terms of the efficacy and incidence of adverse events following treatment with AIs. Pharmacogenetics has the potential to predict clinical outcomes based on patients' genetic information, paving the way towards personalized treatment.

AREAS COVERED

This article reviews pharmacogenetic studies of AIs, including pharmacokinetic and pharmacodynamic aspects, highlighting those studies where the efficacy and adverse events of AIs have been examined using both candidate gene and genome-wide approaches.

EXPERT OPINION

Pharmacogenetics is a promising approach to develop personalized medicine with AIs. However, the application of pharmacogenetics to predict therapeutic efficacy and adverse events in breast cancer patients is still far from implementation in routine clinical practice. Large, comprehensive, multicenter studies that simultaneously evaluate multiple genes and pathways, including rare variants, are warranted in order to produce reliable and informative results. The ultimate aim is to develop clinically-relevant guidelines for breast cancer therapy.

A cross-sectional survey of pain catastrophising and acupuncture use among breast cancer survivors

INTRODUCTION

Treatment-related joint pain affects almost half of all women with breast cancer using aromatase inhibitors and is a major reason for terminating treatment. Although acupuncture is becoming an increasingly popular, evidence-based option for treating pain, little is known about the potential influence of psychological factors on acupuncture use.

OBJECTIVE

We aimed to evaluate the association between pain catastrophising and use of acupuncture in breast cancer survivors experiencing arthralgia.

METHODS

We conducted a cross-sectional survey of arthralgic breast cancer patients. Patients were asked if they had used acupuncture since their cancer diagnosis. The Pain Catastrophising Scale (PCS) was used to measure negative coping styles related to the experience of pain. We performed multiple logistic regression analysis to evaluate the relationship between pain catastrophising and acupuncture use, adjusting for covariates.

RESULTS

Of the 424 participants, 69 (16%) reported use of acupuncture since their breast cancer diagnosis. In multivariate analyses, compared to those in the lowest PCS score tertile, patients with the highest PCS scores were more likely to have used acupuncture (p=0.03). In particular, patients with high levels of rumination (p=0.005) and magnification (p=0.008) were more likely to have used acupuncture. Helplessness was not associated with acupuncture use (p=0.23).

CONCLUSIONS

High levels of pain catastrophising, and specifically the processes of rumination and magnification, were associated with greater acupuncture use. We believe this could have important implications for understanding which population is more likely to seek acupuncture treatment and how this alternative therapy could be better targeted to these patients.

The influence of genetic polymorphisms on the efficacy and side effects of anastrozole in postmenopausal breast cancer patients

Breast cancer is a common cause of cancer mortality among women. Several genetic factors have been implicated in its development. Current treatment guidelines for estrogen receptor-positive breast cancer recommend that anastrozole [or any of the other two aromatase inhibitors (letrozole and exemestane)] is used as an alternative to tamoxifen or following several years of tamoxifen treatment. Nevertheless, this approach is still associated with many challenges, ranging from the recurrence of breast cancer to considerable interindividual variability in the tolerability of anastrozole, which may cause adverse effects, such as musculoskeletal symptoms, and lead to the withdrawal of many patients from treatment. Variabilities in the genes encoding the drug target (aromatase) or its metabolizing enzymes (CYP3A and UGT1A) contribute toward the interindividual variability in anastrozole's pharmacokinetics and/or pharmacodynamics. This paper reviews the role of genetic polymorphisms of CYP19A1, CYP3A4, and UGT1A4 in the responses of female hormone receptor-positive postmenopausal breast cancer patients to anastrozole. Many reviews in the literature have suggested that the study of functional polymorphisms and investigation of relevant genetic markers may provide valuable information in predicting responses to anastrozole in terms of its therapeutic and adverse effects. Nevertheless, more studies are required before the knowledge of its pharmacogenomics can be applied to the individualization of treatment to ensure that patients receive the maximum benefits. Therefore, future analyses, including but not limited to genome-wide association studies, are encouraged to address some of the gray areas in the pharmacogenomics of anastrozole therapy in postmenopausal breast cancer cases; this will help in providing guidance for future pharmacogenomics protocols when anastrozole is utilized in patients' management.

Randomized exercise trial of aromatase inhibitor-induced arthralgia in breast cancer survivors

PURPOSE

Arthralgia occurs in up to 50% of breast cancer survivors treated with aromatase inhibitors (AIs) and is the most common reason for poor AI adherence. We conducted, in 121 breast cancer survivors receiving an AI and reporting arthralgia, a yearlong randomized trial of the impact of exercise versus usual care on arthralgia severity.

PATIENTS AND METHODS

Eligibility criteria included receiving an AI for at least 6 months, reporting ≥ 3 of 10 for worst joint pain on the Brief Pain Inventory (BPI), and reporting < 90 minutes per week of aerobic exercise and no strength training. Participants were randomly assigned to exercise (150 minutes per week of aerobic exercise and supervised strength training twice per week) or usual care. The BPI, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire were completed at baseline and at 3, 6, 9, and 12 months. Intervention effects were evaluated using mixed-model repeated measures analysis, with change at 12 months as the primary end point.

RESULTS

Over 12 months, women randomly assigned to exercise (n = 61) attended 70% (± standard deviation [SD], 28%) of resistance training sessions and increased their exercise by 159 (± SD, 136) minutes per week. Worst joint pain scores decreased by 1.6 points (29%) at 12 months among women randomly assigned to exercise versus a 0.2-point increase (3%) among those receiving usual care (n = 60; P < .001). Pain severity and interference, as well as DASH and WOMAC pain scores, also decreased significantly at 12 months in women randomly assigned to exercise, compared with increases for those receiving usual care (all P < .001).

CONCLUSION

Exercise led to improvement in AI-induced arthralgia in previously inactive breast cancer survivors.

Estrogen alone and joint symptoms in the Women's Health Initiative randomized trial

OBJECTIVE

Although joint symptoms are commonly reported after menopause, observational studies examining exogenous estrogen's influence on joint symptoms provide mixed results. Against this background, estrogen-alone effects on joint symptoms were examined in post hoc analyses in the Women's Health Initiative randomized, placebo-controlled, clinical trial.

METHODS

A total of 10,739 postmenopausal women who have had a hysterectomy were randomized to receive daily oral conjugated equine estrogens (0.625 mg/d) or a matching placebo. The frequency and severity of joint pain and joint swelling were assessed by questionnaire in all participants at entry and on year 1, and in a 9.9% random subsample (n = 1,062) after years 3 and 6. Logistic regression models were used to compare the frequency and severity of symptoms by randomization group. Sensitivity analyses evaluated adherence influence on symptoms.

RESULTS

At baseline, joint pain and joint swelling were closely comparable in the randomization groups (about 77% with joint pain and 40% with joint swelling). After 1 year, joint pain frequency was significantly lower in the estrogen-alone group compared with the placebo group (76.3% vs 79.2%, P = 0.001), as was joint pain severity, and the difference in pain between randomization groups persisted through year 3. However, joint swelling frequency was higher in the estrogen-alone group (42.1% vs 39.7%, P = 0.02). Adherence-adjusted analyses strengthen estrogen's association with reduced joint pain but attenuate estrogen's association with increased joint swelling.

CONCLUSIONS

The current findings suggest that estrogen-alone use in postmenopausal women results in a modest but sustained reduction in the frequency of joint pain.

Vitamin d: are we ready to supplement for breast cancer prevention and treatment?

Vitamin D deficiency is a potentially modifiable risk factor that may be targeted for breast cancer prevention and treatment. Preclinical studies support various antitumor effects of vitamin D in breast cancer. Numerous observational studies have reported an inverse association between vitamin D status, including circulating 25-hydroxyvitamin D (25(OH)D) levels, and breast cancer risk. The relationship between vitamin D and mammographic density, a strong predictor of breast cancer risk, remains unclear. Studies analyzing the link between genetic polymorphisms in vitamin D pathway genes and breast cancer incidence and prognosis have yielded inconsistent results. Vitamin D deficiency among breast cancer patients has been associated with poorer clinical outcomes and increased mortality. Despite a number of clinical trials of vitamin D supplementation, the efficacy, optimal dosage of vitamin D, and target blood level of 25(OH)D for breast cancer prevention have yet to be determined. Even with substantial literature on vitamin D and breast cancer, future studies need to focus on gaining a better understanding of the biologic effects of vitamin D in breast tissue. Despite compelling data from experimental and observational studies, there is still insufficient data from clinical trials to make recommendations for vitamin D supplementation for breast cancer prevention or treatment.

Online discussion of drug side effects and discontinuation among breast cancer survivors

PURPOSE

While patients often use the internet as a medium to search for and exchange health-related information, little is known about the extent to which patients use social media to discuss side effects related to medications. We aim to understand the frequency and content of side effects and associated adherence behaviors discussed by breast cancer patients related to using aromatase inhibitors (AIs), with particular emphasis on AI-related arthralgia.

METHODS

We performed a mixed methods study to examine content related to AI associated side effects posted by individuals on 12 message boards between 2002 and 2010. We quantitatively defined the frequency and association between side effects and AIs and identified common themes using content analysis. One thousand randomly selected messages related to arthralgia were coded by two independent raters.

RESULTS

Among 25 256 posts related to AIs, 4589 (18.2%) mentioned at least one side effect. Top-cited side effects on message boards related to AIs were joint/musculoskeletal pain (N = 5093), hot flashes (1498), osteoporosis (719), and weight gain (429). Among the authors posting messages who self-reported AI use, 12.8% mentioned discontinuing AIs, while another 28.1% mentioned switching AIs. Although patients often cited severe joint pain as the reason for discontinuing AIs, many also offered support and advice for coping with AI-associated arthralgia.

CONCLUSION

Online discussion of AI-related side effects was common and often related to drug switching and discontinuation. Physicians should be aware of these discussions and guide patients to effectively manage side effects of drugs and promote optimal adherence.

Breast cancer survivorship symptom management: current perspective and future development

Increasing numbers and longevity of cancer survivors has furthered our insight into the factors affecting their health outcomes, suggesting that multiple factors play a role (e.g., effects of cancer treatments and health behaviors). Emotional and physical symptoms may not always receive sufficient attention. In this short narrative review highlighting recent literature, we describe the most common physical and emotional symptoms of breast cancer survivors aged 50 years and older and outline a multidisciplinary symptom management approach, regardless of symptom etiology.

Prevalence and risk factors for insomnia among breast cancer patients on aromatase inhibitors

PURPOSE

Insomnia is increasingly recognized as a major symptom outcome in breast cancer; however, little is known about its prevalence and risk factors among women receiving aromatase inhibitors (AIs), a standard treatment to increase disease-free survival among breast cancer patients.

METHODS

A cross-sectional survey study was conducted among postmenopausal women with stage 0-III breast cancer receiving adjuvant AI therapy at an outpatient breast oncology clinic of a large university hospital. The insomnia severity index (ISI) was used as the primary outcome. Multivariate logistic regression analyses were performed to evaluate risk factors.

RESULTS

Among 413 participants, 130 (31.5 %) had subthreshold insomnia on the ISI, and 77 (18.64 %) exceeded the threshold for clinically significant insomnia. In a multivariate logistic regression model, clinically significant insomnia was independently associated with severe joint pain (adjusted odds ratio (AOR) 4.84, 95 % confidence interval (CI) 1.71-13.69, P = 0.003), mild/moderate hot flashes (AOR 2.28, 95 % CI 1.13-4.60, P = 0.02), severe hot flashes (AOR 2.29, 95 % CI 1.23-6.81, P = 0.015), anxiety (AOR 1.99, 95 % CI 1.08-3.65, P = 0.027), and depression (AOR 3.57, 95 % CI 1.48-8.52, P = 0.004). Age (>65 vs. <55 years; AOR 2.31; 95 % CI 1.11-4.81; P = 0.026) and time since breast cancer diagnosis (<2 vs. 2-5 years; AOR 1.94; 95 % CI 1.02-3.69; P = 0.045) were also found to be significant risk factors. Clinical insomnia was more common among those who used medication for treating insomnia and pain.

CONCLUSIONS

Insomnia complaints exceed 50 % among AI users. Clinically significant insomnia is highly associated with joint pain, hot flashes, anxiety and depression, age, and time since diagnosis.

The time since last menstrual period is important as a clinical predictor for non-steroidal aromatase inhibitor-related arthralgia

Background

The clinical predictors of aromatase inhibitor-related arthralgia (AIA), a drug-related adverse reaction of aromatase inhibitors (AIs), remain unclear.

Methods

AIA was prospectively surveyed every 4 months in 328 postmenopausal breast cancer patients administered a non-steroidal AI (anastrozole). Various clinicopathological parameters were recorded and analyzed (chi-square test, Fisher's exact test and logistic regression analysis).

Results

The mean observation period was 39.9 months. AIA manifested in 114 patients (34.8%), with peaks of onset at 4 (33.7%) and 8 months (11.4%) after starting AI administration. Some cases manifested even after 13 months. AIA tended to occur in younger patients (incidences of 46.3%, 37.4% and 28.0% for ages of < 55, 55-65 and > 65 years, respectively (p = 0.063)) and decreased significantly with the age at menarche (53.3%, 35.3% and 15.4% for < 12, 12-15 and > 15 years, respectively (p = 0.036)). The incidences were 45.1%, 46.3 and 25.1% for the time since the last menstrual period (LMP) < 5 years, 5-10 years and > 10 years, being significantly lower at > 10 years (p < 0.001). In logistic regression analysis, the AIA incidence was significantly lower in the time since LMP > 10-year group versus the < 5-year group (odds ratio 0.44, p = 0.002), but the age at menarche showed no association. AIA manifested significantly earlier (≤ 6 months) as the time since LMP became shorter (< 5 years).

Conclusion

AIA tends to manifest early after starting AI, but some cases show delayed onset. The incidence was significantly lower in patients with a duration of > 10 years since LMP. When the time since LMP was short, the onset of AIA was significantly earlier after starting AI administration.

Pharmacogenetics of anti-estrogen treatment of breast cancer

A major effort is underway to select genetic polymorphisms potentially relevant to the clinical efficacy and safety of endocrine treatment of breast cancer. Genetic factors of the host that affect the metabolism of tamoxifen, a widely used drug for the adjuvant treatment of breast cancer, have received particular attention. Cytochrome P450 isoform 2D6 (CYP2D6) is a key step in the metabolism of tamoxifen to its active moiety endoxifen. Women with functionally deficient genetic variants of CYP2D6 who are given drugs that inhibit CYP2D6 are exposed to low endoxifen plasma levels and may enjoy reduced benefits from tamoxifen treatment. Therefore, CYP2D6 status may be an important predictor of the benefits of tamoxifen to an individual; unfortunately, the data are not uniformly concordant, and definitive evidence that would suggest the routine analysis of CYP2D6 before commencing tamoxifen treatment is not yet available. Recent research has focused on the role UDP-glucuronosyltransferases, a family of metabolizing enzymes that play an important role in the metabolic clearance of tamoxifen and of the aromatase inhibitors as well, and how interindividual differences in these enzymes may play a role in the clinical outcome upon administration of anti-estrogen treatment. In conclusion, whether a pharmacogenetic profile should be obtained prior to initiating tamoxifen therapy is currently a matter of debate, although summing up all the scientific evidence available on this issue it appears that the genetic screening would be an useful support for clinical decision making in selected patients.

Individualization of treatment strategies

This section focuses on different aspects of the individualization of hormone treatment in breast cancer. This includes tumor-related biological factors such as expression of hormone receptors, HER-2, and Ki-67; host-related factors such as CYP2D6 or body mass index, and risk and/or development of specific toxicities and treatment adherence. The best predictor of response to hormonal interventions is the expression of hormone receptors, in particular, estrogen receptors. Treatment adherence and compliance are key factors and strategies aiming to identify and intervene when patients are at risk of abandoning treatment. Currently, routine assessment of CYP2D6 is not recommended to guide tamoxifen treatment. Likewise, there are no criteria regarding bone mass density, lipid profile, or arthralgias to recommend one class of agent versus another. Aromatase inhibitors should not be administered to patients who are pre- or perimenopausal.

Vitamin D and breast cancer: interpreting current evidence

Preclinical investigations and selected clinical observational studies support an association between higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk. However, the recently updated report from the Institute of Medicine concluded that, for cancer and vitamin D, the evidence was 'inconsistent and insufficient to inform nutritional requirements'. Against this background, reports examining vitamin D intake, 25-hydroxyvitamin D levels and breast cancer incidence and outcome were reviewed. Current evidence supports the pursuit of several research questions but not routine 25-hydroxyvitamin D monitoring and vitamin D supplementation to reduce breast cancer incidence or improve breast cancer outcome.

Joint symptoms, aromatase inhibitor-related adverse reactions, are indirectly associated with decreased serum estradiol

Background. Joint symptoms (JSs) are problematic adverse drug reactions (ADRs) of aromatase inhibitors (AIs). Involvement of decreased serum estradiol (SE) has been suggested. Patients and Methods. 104 postmenopausal breast cancer patients administered an AI were prospectively investigated regarding various clinical parameters, JS and hot flashes as ADRs, and the SE level. Results. JS manifested in 31.7% of patients and hot flashes in 18.3%. Chi-square testing showed a significantly higher incidence of JS in several patient strata: <55 years old, decreased SE, and elevated total cholesterol (TC). In univariate analysis, JS correlated significantly with a pre-AI % YAM of ≥80%, decreased SE, and elevated TC. Eight (7.7%) patients maintained SE at ≥5 pg/mL for >6 consecutive months, with no JS. In chi-square testing, hot flashes showed a significantly higher incidence in patients <55 years old. Conclusion. AI-ADRs occurred more readily in younger patients. Decreased SE may be indirectly involved in JS.

Association of functional polymorphisms in CYP19A1 with aromatase inhibitor associated arthralgia in breast cancer survivors

Introduction

Aromatase inhibitor-associated arthralgia (AIAA) is a common and often debilitating symptom in breast cancer survivors. Since joint symptoms have been related to estrogen deprivation through the menopausal transition, we hypothesized that genetic polymorphisms in CYP19A1, the final enzyme in estrogen synthesis, may be associated with the occurrence of AIAA.

Methods

We performed a cross-sectional study of postmenopausal women with stage 0 to III breast cancer receiving adjuvant aromatase inhibitor (AI) therapy. Patient-reported AIAA was the primary outcome. DNA was genotyped for candidate CYP19A1 polymorphisms. Serum estrogen levels were evaluated by radioimmunoassay. Multivariate analyses were performed to examine associations between AIAA and genetic variants controlling for possible confounders.

Results

Among 390 Caucasian participants, 50.8% reported AIAA. Women carrying at least one 8-repeat allele had lower odds of AIAA (adjusted odds ratio (AOR) 0.41, 95% confidence interval (CI) 0.21 to 0.79, P = 0.008) after adjusting for demographic and clinical covariates. Estradiol and estrone were detectable in 47% and 86% of subjects on AIs, respectively. Although these post-AI levels were associated with multiple genotypes, they were not associated with AIAA. In multivariate analyses, women with more recent transition into menopause (less than five years) were significantly more likely to report AIAA than those greater than ten years post-menopause (AOR 3.31, 95% CI 1.72 to 6.39, P < 0.001).

Conclusions

Functional polymorphism in CYP19A1 and time since menopause are associated with patient-reported AIAA, supporting the hypothesis that the host hormonal environment contributes to the pathophysiology of AAIA. Prospective investigation is needed to further delineate relationships between host genetics, changing estrogen levels and AIAA.

Aromatase inhibitor therapy: toxicities and management strategies in the treatment of postmenopausal women with hormone-sensitive early breast cancer

Aromatase inhibitors (AIs) have been shown to reduce the risk of breast cancer recurrence and are widely used today as adjuvant therapy in women with early stage endocrine-responsive breast cancer. Aromatase inhibitors may be prescribed as initial hormonal therapy, sequentially following 2-3 years of tamoxifen, or as extended adjuvant therapy (following 5 years of tamoxifen). Aromatase inhibitors are generally well tolerated; however, certain side effects, particularly arthralgia/musculoskeletal symptoms and gynecologic effects, may result in poor adherence to treatment. Patients receiving adjuvant therapy with an AI should be counseled regarding possible side effects and the importance of completing treatment. Interventions to ameliorate side effects should be individualized based on symptoms, comorbid conditions, and pre-existing therapies. In addition, bone and cardiovascular health should be monitored during AI therapy. Prompt therapeutic management of common side effects associated with AIs may provide patients with the opportunity to receive the full benefit of their adjuvant hormonal treatment while minimizing toxicity.

Vitamin D threshold to prevent aromatase inhibitor-induced arthralgia: a prospective cohort study

Aromatase inhibitor (AI)-associated arthralgia limits adherence to therapy in breast cancer. The pathophysiology may involve vitamin D status. We wished to establish the optimal concentration of 25(OH)D that prevents or minimizes arthralgia. We used a prospective cohort of 290 women starting AI in whom baseline vitamin D was measured. All received daily vitamin D(3) (800 IU) with calcium. Women with baseline 25(OH)D concentration <30 ng/ml also received 16,000 IU of D(3) orally every 2 weeks. The primary outcome was incident or worsening joint pain derived from baseline and 3-month visual analogic scale (VAS) for joint pain. Regression models were used to analyse the association between vitamin D concentrations at 3 months and pain adjusting for age, BMI, season when the sample was drawn, aromatase inhibitor (exemestane vs. letrozole/anastrozole), prior tamoxifen therapy, baseline NTX, and previous fracture. 90% of women had a 25(OH)D <30 ng/ml at baseline. After supplementation (daily 800 IU and additional 16,000 IU every 2 weeks), 50% of them still failed to reach adequate concentrations at 3 months. In the whole cohort, there was an increase in joint pain (mean 1.16 points SD 2.66; P < 0.001) and the increase was significantly (P = 0.02) attenuated in those that reached concentrations of 25(OH)D of ≥40 ng/ml, with a lower risk of incident arthralgia (OR 0.12 ** [0.03 to 0.40]). A target concentration of 40 ng/ml 25OHD may prevent development of AI arthralgia but higher loading doses are required to attain this level in women with deficiency at baseline.