What to Do and What Not to Do in the Management of Cancer Pain: A Physician Survey and Expert Recommendations

Background

Despite the prevalence of pain among patients with cancer and the availability of pertinent guidelines, the clinical management of oncological pain is decisively insufficient. To address this issue, we evaluated current trends in clinical practice and subsequently generated a list of ten corrective actions—five things to do and five things not to do—for the diagnosis, management, and monitoring of cancer pain.

Methods

The survey included 18 questions about clinical practice surrounding background pain and breakthrough cancer pain (BTcP). Survey questions were developed by a scientific board of 10 physician experts and communicated via email to an expanded panel of physicians in Italy. Responses were tabulated descriptively for analysis.

Results

Of 51 invited physicians, 32 (63%) provided complete survey responses. The responses revealed several incongruencies with current guideline recommendations: physicians did not always diagnose or monitor pain using diagnostically validated or disease-specific instruments; frequently based clinical decision-making on time availability or convenience; and pharmacological therapy was often inappropriate (eg, prescribing NSAIDs or corticosteroids for BTcP). The list of corrective actions generated by the scientific board favored a guideline-oriented approach that systematically characterizes oncological pain and implements treatment based on pain characteristics (eg, fast-acting transmucosal opioids for BTcP) and evidence-based recommendations.

Conclusion

Oncologists require better education and training about the diagnosis, treatment, and monitoring of oncological pain. Physicians should be aware of current guideline recommendations as well as available pharmacological tools for BTcP.

Oxycodone/Acetaminophen: The Tailoring Combination Treatment for Specific Clinical Profile of Opioid Well-Responsive Cancer Pain

Background

International guidelines recommend moderate-to-severe cancer pain to be treated with strong opioids. However, pain management remains an unsolved matter, at least in the demanding oncology and palliative care setting. Although cancer pain consists of multiple components, which interact in complex ways where combination therapy can better intercept multiple pain characteristics, few studies have used a non-opioid/opioid association to exploit possible synergistic actions. Even the efforts of a recent approach emphasizing appropriate pain assessment and accurate classification to obtain personalized pain management have not produced a satisfactory analgesic strategy.

Objective

This analysis was intended to evaluate the effectiveness of the immediate release fixed combination of oxycodone/acetaminophen (OxyIR/Par) for the treatment of moderate-to-severe intensity background pain used alone or in combination with other strong opioids in cancer patients with breakthrough cancer pain (BTcP). This is a secondary analysis of a wider observational, prospective, multicenter study [Italian Oncologic Pain multiSetting Multicentric Survey (IOPS-MS)] performed on 179 patients treated with opioids for cancer pain who received the fixed combination of oxycodone/acetaminophen (OxyIR/Par) for the treatment of background pain (BGP).

Results

Cancer patients with breakthrough cancer pain and controlled BGP (Background Pain) were classified according to the presence of analgesic therapy with tablets of fixed combination OxyIR/Par alone (group A, n=120) or tablets of fixed combination OxyIR/Par combined with other strong opioids (group B, n=59). Clinical features of group A were different to group B: higher mean Karnofsky Performance Status Index 70.3% (95% CI=67.2–73.5; median=70, CI=60–80) vs 58.3 (95% CI=53.4–63.2; median=50, CI=45–70) (P<0.001), and mainly group A patients were treated in an ambulatory setting (55.0% group A vs 33.9% group B) (p<0.001). Both groups had managed BGP with similar mean dosages (group A: 12.0, CI=10.5–13.4; group B: 13.1, CI=11.0–15.1) and frequencies of OxyIR/Par alone for group A and in association to other opioids for group B, but Breakthrough cancer Pain (BTcP) exhibited different characteristics in the two groups, showing a lower mean intensity numerical rating scale (NRS) of 7.5 (95% CI=7.2–7.7; median=7, CI=7–8 group A) vs 7.9 (95% CI=7.6, 8.2; median= 8, CI=7–9 group B) (P=0.04) and a higher percentage of patients had a faster onset, defined as the maximum intensity reached in less than 10 minutes, 81.7% (N=98) in group A vs 59.3% (n=35) in group B (P=0.002).

Conclusion

This is the first analysis about the efficacy of an immediate-release fixed combination of OxyIR/Par in the real world for moderate-to-severe background cancer pain and breakthrough cancer pain. The oral fixed combination OxyIR/Par provided an adequate level of analgesia for moderate–severe background cancer pain, in a different cohort of cancer patients with different performance status, both in ambulatory and palliative settings. The low dosage of fixed combination OxyIR/Par was effective alone or in association with other opioids.

Breakthrough Cancer Pain Clinical Features and Differential Opioids Response: A Machine Learning Approach in Patients With Cancer From the IOPS-MS Study

PURPOSE

A large proportion of patients with cancer suffer from breakthrough cancer pain (BTcP). Several unmet clinical needs concerning BTcP treatment, such as optimal opioid dosages, are being investigated. In this analysis the hypothesis, we explore with an unsupervised learning algorithm whether distinct subtypes of BTcP exist and whether they can provide new insights into clinical practice.

METHODS

Partitioning around a k-medoids algorithm on a large data set of patients with BTcP, previously collected by the Italian Oncologic Pain Survey group, was used to identify possible subgroups of BTcP. Resulting clusters were analyzed in terms of BTcP therapy satisfaction, clinical features, and use of basal pain and rapid-onset opioids. Opioid dosages were converted to a unique scale and the BTcP opioids-to-basal pain opioids ratio was calculated for each patient. We used polynomial logistic regression to catch nonlinear relationships between therapy satisfaction and opioid use.

RESULTS

Our algorithm identified 12 distinct BTcP clusters. Optimal BTcP opioids-to-basal pain opioids ratios differed across the clusters, ranging from 15% to 50%. The majority of clusters were linked to a peculiar association of certain drugs with therapy satisfaction or dissatisfaction. A free online tool was created for new patients’ cluster computation to validate these clusters in future studies and provide handy indications for personalized BTcP therapy.

CONCLUSION

This work proposes a classification for BTcP and identifies subgroups of patients with unique efficacy of different pain medications. This work supports the theory that the optimal dose of BTcP opioids depends on the dose of basal opioids and identifies novel values that are possibly useful for future trials. These results will allow us to target BTcP therapy on the basis of patient characteristics and to define a precision medicine strategy also for supportive care.

Denosumab for cancer-related bone loss

INTRODUCTION

Prolonged use of anti-cancer treatments in breast and prostate tumors alters physiological bone turnover leading to adverse skeletal related events, such as osteoporosis, loss of bone mass, and increased risk of fractures. These complications known as cancer treatment-induced bone loss (CTIBL) should be managed with bone targeting agents such as the bisphosphonates and denosumab. The latter is a monoclonal antibody against the receptor activator of nuclear factor-kB ligand (RANKL) that suppresses osteoclasts function and survival increasing bone mass.

AREAS COVERED

This review will focus on the mechanisms associated with bone loss induced by cancer treatments and the most recent evidence about the use of denosumab as preventive and therapeutic strategy to protect bone health. Moreover, we will discuss several key aspects regarding the clinical practical use of denosumab to optimize the management of CTLIB in breast and prostate cancer.

EXPERT OPINION

Denosumab treatment strongly prevents cancer therapies-related skeletal issues in breast and prostate cancer with a good safety profile. Adjuvant six-monthly denosumab delays the time to first fracture onset in early stage breast cancer patients with normal or altered bone mineral density (BMD). Similarly, denosumab treatment is able to prevent fractures and BMD loss in nonmetastatic prostate cancer patients.

Breakthrough cancer pain clinical features and differential opioids response: A machine learning approach in 4,016 cancer patients of IOPS-MS study

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Background: A large proportion of patients with cancer suffer from Breakthrough cancer pain (BTcP). Several unmet clinical needs concerning BTcP treatment, like optimal opioids dosage, are being investigated. We explored with an unsupervised learning algorithm whether distinct subtypes of BTcP exist and whether they can provide new insights into clinical practice. Methods: We used partitioning around medoids algorithm on a large dataset of patients with BTcP previously collected by the IOPS group in order to identify possible subgroups of BTcP; the input of the algorithm consisted of different BTcP features, like its duration or its intensity. Silhouette statistics was used to pick an optimal number of clusters. Resulting clusters were analyzed in terms of BTcP therapy satisfaction, clinical features and usage of basal pain and rapid onset opioids. Opioids dosages were converted to a unique scale and BTcP-opioids-to-basal-pain-opioids ratio (OpR) was calculated for each patient. Polynomial logistic regression was used to catch non-linear relationships between therapy satisfaction and opioids usage. Results: The cohort comprised 4016 patients with controlled basal pain and suffering from BTcP. Our algorithm identified 12 distinct BTcP clusters. Optimal OpRs differed across the clusters, ranging from 15% to 50%. In the whole cohort, OpR was more clearly associated with therapy satisfaction compared with BTcP opioids or basal pain opioids alone. The majority of the clusters were linked to peculiar association of certain drugs with therapy satisfaction or dissatisfaction. A free online tool was created for new patients cluster computation ( https://mancapaolo.shinyapps.io/UCBM_BTcPclusters/ ) in order to validate these clusters in future studies and to provide a possible, handy indications for personalized BTcP therapy. Conclusions: This work proposes a classification for BTcP and identifies subgroups of patients with unique efficacy of different pain medications. This work supports the theory that the optimal dose of BTcP opioids depends on the dose of basal opioids and identifies novel values, possibly useful for future trials.

Pharmacology of Ranolazine versus Common Cardiovascular Drugs in Patients with Early Diastolic Dysfunction Induced by Anthracyclines or Nonanthracycline Chemotherapeutics: A Phase 2b Minitrial

We have reported that anthracyclines and nonanthracycline chemotherapeutics caused diastolic dysfunction in cancer patients without cardiovascular risk factors. Diastolic dysfunction occurred as early as 1 week after the last chemotherapy cycle and manifested as impaired myocardial relaxation at echocardiography or persistent elevations of B-type natriuretic peptide (BNP) or troponin. The antianginal drug ranolazine shows cardiac relaxant effects that we considered of value to treat early diastolic dysfunction induced by cancer drugs; therefore, 24 low-risk patients with post-chemotherapy diastolic dysfunction were randomized (1:1) to ranolazine or the investigator's choice of common cardiovascular drugs, such as β-blockers and/or angiotensin-converting enzyme inhibitors or loop diuretics (best standard therapy, BST). After 5 weeks, 12 of 12 patients on ranolazine recovered from diastolic dysfunction, whereas 3 of 12 patients on BST did not improve; however, adverse events (not serious) were apparently more frequent for ranolazine than for BST (4/12 vs. 1/12). Ranolazine did not lower blood pressure, whereas BST reduced systolic pressure and caused a trend toward a reduced diastolic pressure. Most patients at randomization showed tachycardia resulting from chemotherapy-related anemia. Hemoglobin recovery contributed to normalizing heart rate in these patients; however, some patients in the ranolazine arm developed tachycardia through chronotropic effects of high BNP levels and returned to a normal heart rate through the effects of ranolazine on decreasing BNP levels. This minitrial describes the potential effects of ranolazine on relieving chemotherapy-related diastolic dysfunction; however, clinical implications of these findings need to be characterized by studies with an adequate sample size. SIGNIFICANCE STATEMENT: The antianginal drug ranolazine causes cardiac relaxant effects that might relieve diastolic dysfunction. In a clinical pharmacology study, 24 patients were randomized (1:1) to receive ranolazine or common cardiovascular drugs to treat early diastolic dysfunction induced by anthracycline-based or nonanthracycline chemotherapy. Ranolazine relieved diastolic dysfunction in these patients. The safety profile of ranolazine in cancer patients is similar to that of the general population. Compared with common cardiovascular drugs, ranolazine relieved diastolic dysfunction without lowering blood pressure. The sample size of this study was nonetheless too small to permit considerations about the potential clinical value of ranolazine for oncologic patients with early diastolic dysfunction induced by anthracyclines or nonanthracycline chemotherapeutics. This information should be obtained by studies with an adequate sample size.

The prognostic and predictive role of hyponatremia in patients with advanced non-small cell lung cancer (NSCLC) with bone metastases

PURPOSE

Hyponatremia and bone metastasis (BMs) are known as negative prognostic factors in patients affected by metastatic non-small cell lung cancer (NSCLC). Hyponatremia is associated with higher risk of osteoporosis and bone fracture, but no data are available about the relationship between hyponatremia and bone metastasis. This study aims to analyze the prognostic impact of hyponatremia in NSCLC patients with bone metastases.

METHODS

We retrospectively collected data about advanced NSCLC patients. Survival curves were estimated using Kaplan-Meier method, and comparisons were made using chi-square test.

RESULTS

Six hundred forty-seven patients were enrolled into the study. BMs were present in 264 patients (41%) at diagnosis, while hyponatremia appeared in 237 (37%) patients during the first-line treatment. Patients without BMs had a median overall survival (mOS) of 15.9 months (95% CI 14.1-17.9) versus 11.4 months (95% CI 9.4-13.4) for patients with BMs (p = 0.001). Eunatremic patients had a better outcome (mOS 16.3 months, 95% CI 14.6-18.0 vs 10.3 months, 95% I 7.6-12.8, p = 0.003). Considering the two variables, patients with BMs and hyponatremia had a mOS of 10.1 months (95% CI 4.3-15.9), patients with hyponatremia without BMs 11.9 months (95% CI 11.4-12.4), while mOS was 13.1 months (95% CI 12.0-14.2) for eunatremic patients with BMs versus 17.1 months (95% CI 15.2-19.1) in eunatremic patients without BMs (p = 0.0020). Hyponatremic patients developed metachronous BMs significantly earlier (3.73 vs 5.76 months, p = 0.0187).

CONCLUSIONS

Our study showed that hyponatremia is an important prognostic factor and it should be necessarily considered to enhance the management of NSCLC patients with BMs.

The Endogenous Lusitropic and Chronotropic Agent, B-Type Natriuretic Peptide, Limits Cardiac Troponin Release in Cancer Patients with an Early Impairment of Myocardial Relaxation Induced by Anthracyclines

We have reported that cancer patients treated with anthracycline-based or nonanthracycline chemotherapy developed an early impairment of myocardial relaxation at echocardiography or persistent elevations of the cardiac hormone B-type natriuretic peptide (BNP). Post-hoc pharmacologic analyses showed that BNP elevations were induced by impaired relaxation and caused positive lusitropic effects that maintained normal relaxation. High BNP levels and impaired relaxation were therefore characterized as mutually exclusive manifestations of diastolic dysfunction, but high BNP levels resulted in positive chronotropism and inappropriate tachycardia. Some patients developed increased circulating levels of cardiac troponin I isoform (cTnI), a marker of cardiomyocyte necrosis. Here we have characterized whether cTnI elevations correlated with diastolic dysfunction that manifested as impaired relaxation or a high level of BNP. The effects of high BNP levels on cTnI elevations were also characterized. We show that impaired relaxation or high BNP levels were significantly more frequent in patients with cTnI elevations. High BNP levels diminished the plasma peak and area under the curve of cTnI, but this result was accompanied by inappropriate tachycardia. cTnI elevations occurred only in patients treated with anthracyclines; moreover, the association of impaired relaxation or high BNP levels with cTnI elevations was significantly more frequent in doxorubicin-treated patients compared with patients treated with its analog, epirubicin. These findings describe cause-and-effect relations between impaired relaxation and cardiomyocyte necrosis, illuminate the role of anthracycline analogs, denote that the beneficial effects of BNP in relieving impaired relaxation and cardiomyocyte necrosis are counterbalanced by inappropriate tachycardia. Patients showing troponin elevations and impaired relaxation or high BNP levels should be treated with lusitropic drugs that lack a positive chronotropism.

Body Mass Index as a Risk Factor for Toxicities in Patients with Advanced Soft-Tissue Sarcoma Treated with Trabectedin

OBJECTIVES

Low body mass index (BMI) and/or low lean body mass have been shown to be risk factors for chemotherapy-related toxicities in a number of different cancers. However, no data are available regarding the role of BMI as a risk factor for developing toxicities related to the novel anticancer agent, trabectedin, in patients with soft-tissue sarcoma (STS). We evaluated the role of BMI as a risk factor for trabectedin-related toxicity in patients with STS.

METHODS

Data from 51 patients with metastatic/advanced STS treated with trabectedin after progression on ≥1 anthracycline ± ifosfamide regimen were retrospectively reviewed.

RESULTS

Eighteen patients (35.3%) were underweight, and the remainder were of normal bodyweight (45.1%) or overweight (19.6%). Neutropenia of any grade (77.8 vs. 33.3%) and grade 3-4 neutropenia (50.0 vs. 18.2%) occurred more frequently in the underweight versus normal/overweight patients (p = 0.025). Febrile neutropenia also occurred more frequently in underweight patients. Differences remained statistically significant after adjusting for other predictors of toxicity. There were no significant differences in other hematological and nonhematological toxicities between the groups.

CONCLUSIONS

The data suggest for the first time that BMI should be considered a risk factor for neutropenia in patients with STS treated with trabectedin.

Early Diastolic Dysfunction after Cancer Chemotherapy: Primary Endpoint Results of a Multicenter Cardio-Oncology Study

Asymptomatic diastolic dysfunction (DD) with preserved left ventricular ejection fraction (LVEF) is suspected to precede late cardiac events in cancer survivors treated by chemotherapy. We conducted the first multicenter study of early DD induced by chemotherapy. Patients who were candidates for standard dose chemotherapy were screened for the absence of cardiovascular risk factors, LVEF ≥50%, normal-for-age diastolic function at echocardiography (E/A ratio, E wave deceleration time; DT), normal levels of potential DD biomarkers like Nt-proBNP (≤125 pg/mL), and cardiac troponin I (cTnI, ≤0.05 ng/mL). Mitral Doppler (E/E') was left at the investigator's discretion. Chemotherapy-induced DD with preserved LVEF was diagnosed for patients showing LVEF ≥50% and any of the following: Nt-proBNP > 125 pg/mL, cTnI > 0.05 ng/mL, and out-of-range E/A and DT. Eighty patients (68 females, 12 males, median age 49 years) were evaluated at 1 week after chemotherapy (T1) [corrected]. Thirty-three protocol-defined diastolic events were observed (15 Nt-proBNP > 125 pg/mL, 14 grade I DD by E/A and DT, 4 cTnI > 0.05 ng/mL). The events occurred in 29 asymptomatic patients with LVEF ≥50% (36% incidence of DD with preserved LVEF). Interactions occurred between biomarkers and grade I DD. E/E' abnormalities were not observed. Both anthracycline-based and nonanthracycline regimens induced DD. These findings show that biomarkers and echocardiography intercept early DD in otherwise asymptomatic low-risk cancer patients treated by standard dose chemotherapy. These findings therefore call for the adequate cardiac management of cancer patients.

Propolis in the prevention of oral mucositis in breast cancer patients receiving adjuvant chemotherapy: A pilot randomised controlled trial

Chemo-induced oral mucositis (OM) is associated with significant symptoms, treatment delays and increased costs. This pilot randomised controlled trial aimed at evaluating the safety, tolerability and compliance with propolis in breast cancer patients receiving doxorubicin and cyclophosphamide, testing preliminary clinical efficacy of propolis in the prevention of OM, and prospectively evaluating the incidence of OM. Sixty patients were randomised to receive either a dry extract of propolis with 8%-12% of galangin plus mouth rinsing with sodium bicarbonate (experimental arm), or mouth rinsing with sodium bicarbonate (control arm). OM was evaluated with the NCI-CTCAE v4.0 after 5, 10, 15 and 21 days of treatment. Compliance with, tolerability of propolis and adverse events were recorded. The incidence of OM was also prospectively evaluated for 6 months. Two patients (6.7%) manifested a suspected skin reaction to propolis. No patient in the experimental arm developed OM > G1, while in the control arm OM > G1 was 16.7% (p = .02). The incidence of OM ≥ G1 at the end of cycles 2-8 was higher at the second (25%) and fifth cycles (45.8%). Propolis plus bicarbonate was safe, well tolerated and promisingly effective in the prevention of OM in patients with breast cancer.

Developing drugs in cancer-related bone pain

INTRODUCTION

Cancer-related bone pain is a frequent and important key problem for metastatic patients that may reduce quality of life, with related limitations in daily activities and morbidity. Often traditional approach to pain may fail given the complex pathophysiology of this phenomenon.

METHODS

The aim of this review is to describe promising therapies for cancer-related bone pain, from the pathophysiology to the clinical trials currently ongoing. Moreover, any new evidence for better approach to cancer-related bone pain with the traditional drugs is also considered.

CONCLUSIONS

In clinical practice opioids remain the most important pharmacologic treatment for severe pain related to bone cancer. Regard developing drugs, anti-NGF and anti-TrkA are the most investigated new drug in this setting, but a future role in clinical practice is still uncertain.

BMI as a risk factor for toxicities in patients with advanced soft tissue sarcoma treated with trabectedin

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Background: Since the first steps of its clinical development, trabectedin was noticed to be extremely active against myxoid liposarcoma (MLS), whose pathogenesis seems to be associated to the presence of the t(12;16)(q13;p11) translocation, resulting in the expression of FUS-DDIT3 fusion genes. Therefore, the drug seems to induce a maturation of MLS lipoblasts, with transition of the residual spindle non-lipogenic cells into mature vacuolated lipoblasts. This effect could be prevented by the increase of leptin circulating levels in obese patients. For these reasons we designed this retrospective analysis in order to evaluate the BMI status (measure of total adipose content) as a predictors or efficacy of trabectedin in MLS patients. Methods: Patients were treated in cancer centers with trabectedin at the approved dose of 1.5 mg/m2, given as a 24-hour infusion every 3 weeks. This retrospective analysis was preformed on the basis of clinical charts or databases. For the purpose of this analysis only patient with a BMI > 18.5 were included and an the population divided into two categories: normal weight if BMI < 25, overweight > 25. An analysis of the correlation between BMI and objective response (OR) rate, tumor control (TC) rate (OR+stable disease lasting ≥3 months), progression-free survival (PFS) and overall survival (OS) was performed. Results: 62 adult patients with recurrent MLS were enrolled (M/F: 33/29; median age: 53 ys). All patients were doxorubicin-pretreated. The median BMI in the whole population was 22.5 (range: 1.85 – 29.8). No statistically significant differences were identified in terms of OR or TC. On the contrary, PFS (6.8 vs. 3.7 months; p< 0.026, log rank test) and OS (14.9 vs. 8.3 months; p< 0.0001, log rank test) were significantly prolonged in normal weighted patients vs over weighted patients. Six and 12-months Kaplan-Meier PFS estimates and survival rates at 12, 24 and 36 months were also better in those patients. Conclusions: these results seem confirm a role o adipose content as a predictor of resistance to trabectedin in MLS patients. Further studies are warranted to confirm this preliminary observation and understand the biological mechanisms of this relationship.

Drug-induced hepatotoxicity in cancer patients - implication for treatment

INTRODUCTION

All anticancer drugs can cause idiosyncratic liver injury. Therefore, hepatoprotective agents assume particular importance to preserve liver function. Hepatic injury represents 10% of cases of acute hepatitis in adults; drug-related damage is still misjudged because of relative clinical underestimation and difficult differential diagnosis. Chemotherapeutic agents can produce liver toxicity through different pathways, resulting in different categories of liver injuries, but these drugs are not homogeneously hepatotoxic. Frequently, anticancer-induced hepatotoxicity is idiosyncratic and influenced by multiple factors.

AREAS COVERED

The aim of this paper is to perform a review of the literature regarding anticancer-induced liver toxicity. We described hepatotoxicity mechanisms of principal anticancer agents and respective dose reductions. Furthermore, we reviewed studies on hepatoprotectors and their optimal use. Tiopronin, magnesium isoglycyrrhizinate and S-Adenosylmethionine (AdoMet) demonstrated, in some small studies, a potential hepatoprotective activity.

EXPERT OPINION

Actually, in the literature only small experiences are reported. Even though hepatoprotective agents seem to be useful in the oncologic setting, the lack of well-designed prospective Phase III randomized controlled trials is a major limit in the introduction of hepatoprotectors in cancer patients and these kind of studies are warranted to support their use and to give further recommendations for the clinical practice.

Receptor activator of NF-kB (RANK) expression in primary tumors associates with bone metastasis occurrence in breast cancer patients

Background

Receptor activator of NFkB (RANK), its ligand (RANKL) and the decoy receptor of RANKL (osteoprotegerin, OPG) play a pivotal role in bone remodeling by regulating osteoclasts formation and activity. RANKL stimulates migration of RANK-expressing tumor cells in vitro, conversely inhibited by OPG.

Materials and Methods

We examined mRNA expression levels of RANKL/RANK/OPG in a publicly available microarray dataset of 295 primary breast cancer patients. We next analyzed RANK expression by immunohistochemistry in an independent series of 93 primary breast cancer specimens and investigated a possible association with clinicopathological parameters, bone recurrence and survival.

Results

Microarray analysis showed that lower RANK and high OPG mRNA levels correlate with longer overall survival (P = 0.0078 and 0.0335, respectively) and disease-free survival (P = 0.059 and 0.0402, respectively). Immunohistochemical analysis of RANK showed a positive correlation with the development of bone metastases (P = 0.023) and a shorter skeletal disease-free survival (SDFS, P = 0.037). Specifically, univariate analysis of survival showed that “RANK-negative” and “RANK-positive” patients had a SDFS of 105.7 months (95% CI: 73.9–124.4) and 58.9 months (95% CI: 34.7–68.5), respectively. RANK protein expression was also associated with accelerated bone metastasis formation in a multivariate analysis (P = 0.029).

Conclusions

This is the first demonstration of the role of RANK expression in primary tumors as a predictive marker of bone metastasis occurrence and SDFS in a large population of breast cancer patients.