Addressing the unmet needs in lymphedema risk management

Triple mapping for axillary staging after neoadjuvant therapy: Axillary reverse mapping with indocyanine green and dual agent sentinel lymph node biopsy

Axillary staging is 1 of the major issues of current breast cancer management after neoadjuvant systemic therapy (NST). Sentinel lymph node biopsy (SLNB) is an option for clinically node negative patients. Axillary reverse mapping (ARM) was introduced to identify and preserve the lymphatic drainage from the arm. The aim of the presented study is to employ triple mapping (radiocolloid, blue dye and indocyanine green [ICG]) to assess the crossover rate and metastatic involvement of ARM nodes after NST. Clinically node positive patients before NST who were converted to N0 and scheduled for targeted axillary dissection were included. sentinel lymph node (SLN) mapping was performed via dual agent mapping. ICG was used for ARM procedure. Blue, hot and fluorescent nodes and lymphatics were visualized in the axilla using infrared camera system and dual opto-nuclear probe (Euoroprobe3). Fifty-two patients underwent targeted axillary dissection and ARM procedures 12 out of whom had axillary node dissection. 45 of the 52 patients had at least 1 hot or blue SLN identified intraoperatively. Of these, 61.5% cases had hot SLNs, 42.3% had hot and blue, 15.4% had hot/blue/fluorescent, 7.7% had blue/fluorescent, 6 11.5% had hot/fluorescent and 7 13.5% had only clipped nodes. The overall identification rate of ARM-nodes by means of ICG technique was 86.5%. Overall crossover of ARM nodes with SLNs was determined in 36.5%. The ICG intensity was found to be higher in both hot and blue SLNS (8 out of 18 ICG positive cases, 44.4%). In 3 of 52 patients (5.7%) metastatic SLNs were hot or blue but fluorescent which predicts metastatic involvement of the ARM-nodes. More than 1-third of the patients revealed a crossover between arm and breast draining nodes. The higher observed rate of overlap might partially explain why more patients develop clinically significant lymphedema after NST even after sentinel lymph node biopsy alone. The triple mapping provides valuable data regarding the competency of lymphatic drainage and would have the potential to serve selecting patients for lymphovenous by-pass procedures at the index procedure. NST reduces the metastatic involvement of the ARM nodes. However, conservative axillary staging with sparing ARM nodes after NST necessitates further studies with larger sample size and longer follow-up.

Staging Breast Cancer-Related Lymphedema with Bioimpedance Spectroscopy

Background: A number of different classification schemes, with generally similar but not identical criteria, exist to describe the different stages of lymphedema. Criteria may include both subjective and objective assessments. The present study investigated whether bioelectrical impedance parameters had utility in staging breast cancer-related lymphedema. Methods and Results: Hierarchical agglomerative cluster analysis was used to assign women (n = 221) at risk of or with clinically ascribed lymphedema to clusters sharing similar impedance characteristics. Five clusters could be identified with each cluster containing proportions of participants that closely aligned with staging allocation, according to International Society of Lymphology criteria, at initial presentation. The use of cluster analysis for tracking of lymphedema progression or response to treatment is demonstrated. Conclusions: No single assessment provides definitive assignment of a patient to lymphedema stage. Staging is usually achieved by identifying and allocating a patient to a lymphedema stage shared by a group of patients with similar clinical signs. Cluster analysis of impedance data provides similar groupings of patients and could provide a useful adjunct objective assessment for staging lymphedema.

Lymphedema Surveillance and Patient-Reported Anxiety: Comparison Between Volumetric Assessment and Bioimpedance Analysis

Background: Lymphedema is a complication of breast cancer therapy associated with substantial anxiety. We designed a prospective, randomized study to assess the psychosocial impact of different surveillance methods for lymphedema. Methods and Results: In this open-label study of 38 women undergoing breast cancer surgery, we screened for lymphedema using traditional volumetric measurements (circumferential readings from the wrist to the axilla) versus bioimpedance spectroscopy (BIS) using electric current. The primary outcome measure was total anxiety measured by the Beck Anxiety Inventory, a 21-item questionnaire administered at preoperative, 6-week, 3-month, and 6-month postoperative visits (range 0-63 points). Outcome metrics were compared after adjustment for baseline anxiety. There were no differences in clinical characteristics or cancer therapies between groups, except for more reoperation for positive surgical margins in the BIS patients (5% vs. 32%, p = 0.036). Baseline anxiety, depression, and associated medical therapies were similar as well. Only one woman in each group developed lymphedema during the study. Anxiety was higher in the BIS group at baseline (mean Beck score 12.2 vs. 7.2, p < 0.001), but anxiety levels gradually declined by the end of the 6-month study in both groups, with no differences in adjusted anxiety scores between the two groups at any time point during follow-up (all p = NS). Conclusions: In this pilot study of women scheduled for breast cancer surgery, most subjects reported mild anxiety at baseline, and anxiety levels fell during continued lymphedema surveillance visits. There was no difference in patient-reported anxiety when surveillance was performed using standard volumetric versus BIS measurements.

Modulation of Immunity by Lymphatic Dysfunction in Lymphedema

The debilitating condition known as secondary lymphedema frequently occurs after lymphadenectomy and/or radiotherapy for the treatment of cancer. These therapies can damage lymphatic vessels leading to edema, fibrosis, inflammation and dysregulated adipogenesis, which result in profound swelling of an affected limb. Importantly, lymphedema patients often exhibit impaired immune function which predisposes them to a variety of infections. It is known that lymphadenectomy can compromise the acquisition of adaptive immune responses and antibody production; however the cellular mechanisms involved are poorly understood. Here we discuss recent progress in revealing the cellular and molecular mechanisms underlying poor immune function in secondary lymphedema, which has indicated a key role for regulatory T cells in immunosuppression in this disease. Furthermore, the interaction of CD4⁺ T cells and macrophages has been shown to play a role in driving proliferation of lymphatic endothelial cells and aberrant lymphangiogenesis, which contribute to interstitial fluid accumulation in lymphedema. These new insights into the interplay between lymphatic vessels and the immune system in lymphedema will likely provide opportunities for novel therapeutic approaches designed to improve clinical outcomes in this problematic disease.

Lymph transport in rat mesenteric lymphatics experiencing edemagenic stress

OBJECTIVE

To assess lymphatic flow adaptations to edema, we evaluated lymph transport function in rat mesenteric lymphatics under normal and increased fluid volume (edemagenic) conditions in situ.

METHODS

Twelve rats were infused with saline (intravenous infusion, 0.2 mL/min/100 g body weight) to induce edema. We intravitally measured mesenteric lymphatic diameter and contraction frequency, as well as lymphocyte velocity and density before, during, and after infusion.

RESULTS

A 10-fold increase in lymphocyte velocity (0.1-1 mm/s) and a sixfold increase in flow rate (0.1-0.6 μL/min), were observed post infusion, respectively. There were also increases in contraction frequency and fractional pump flow one minute post infusion. Time-averaged wall shear stress increased 10 fold post infusion to nearly 1.5 dynes/cm(2) . Similarly, maximum shear stress rose from 5 to 40 dynes/cm(2) .

CONCLUSIONS

Lymphatic vessels adapted to edemagenic stress by increasing lymph transport. Specifically, the increases in lymphatic contraction frequency, lymphocyte velocity, and shear stress were significant. Lymph pumping increased post infusion, though changes in lymphatic diameter were not statistically significant. These results indicate that edemagenic conditions stimulate lymph transport via increases in lymphatic contraction frequency, lymphocyte velocity, and flow. These changes, consequently, resulted in large increases in wall shear stress, which could then activate NO pathways and modulate lymphatic transport function.

New developments in clinical aspects of lymphatic disease

The lymphatic system is fundamentally important to cardiovascular disease, infection and immunity, cancer, and probably obesity--the four major challenges in healthcare in the 21st century. This Review will consider the manner in which new knowledge of lymphatic genes and molecular mechanisms has demonstrated that lymphatic dysfunction should no longer be considered a passive bystander in disease but rather an active player in many pathological processes and, therefore, a genuine target for future therapeutic developments. The specific roles of the lymphatic system in edema, genetic aspects of primary lymphedema, infection (cellulitis/erysipelas), Crohn's disease, obesity, cancer, and cancer-related lymphedema are highlighted.

Prospective transcriptomic pathway analysis of human lymphatic vascular insufficiency: identification and validation of a circulating biomarker panel

BACKGROUND

In our previous transcriptional profiling of a murine model, we have identified a remarkably small number of specific pathways with altered expression in lymphedema. In this investigation, we utilized microarray-based transcriptomics of human skin for an unbiased a priori prospective candidate identification, with subsequent validation of these candidates through direct serum assay. The resulting multi-analyte biomarker panel sensitively should sensitively discriminate human lymphedema subjects from normal individuals.

METHODS AND FINDINGS

We enrolled 63 lymphedema subjects and 27 normals in our attempt to discover protein analytes that can distinguish diseased individuals from controls. To minimize technical and biologically irrelevant variation, we first identified potential candidates by performing transcriptional microarray analysis on paired diseased and normal skin specimens sampled from the same individuals. We focused our attention on genes with corresponding protein products that are secreted and took these candidates forward to a protein multiplex assay applied to diseased and normal subjects. We developed a logistic regression-based model on an eventual group of six proteins and validated our system on a separate cohort of study subjects. The area under the receiver operating characteristic curve was calculated to be 0.87 (95% CI : 0.75 to 0.97).

CONCLUSIONS

We have developed an accurate bioassay utilizing proteins representing four central pathogenetic modalities of the disease: lymphangiogenesis, inflammation, fibrosis, and lipid metabolism, suggesting that these proteins are directly related to the pathogenesis of the tissue pathology in lymphatic vascular insufficiency. Further studies are warranted to determine whether this newly-identified biomarker panel will possess utility as an instrument for in vitro diagnosis of early and latent disease; the ultimate applicability to risk stratification, quantitation of disease burden, and response to therapy can easily be envisioned.

Biomarkers of Lymphatic Function and Disease

Substantial advances have accrued over the last decade in the identification of the processes that contribute to lymphatic vascular development in health and disease. Identification of distinct regulatory milestones, from a variety of genetic models, has led to a stepwise chronology of lymphatic development. Several molecular species have been identified as important tissue biomarkers of lymphatic development and function. At present, vascular endothelial growth-factor receptor (VEGFR)-3/VEGF-C/VEGF-D signaling has proven useful in the identification of clinical lymphatic metastatic potential and the assessment of cancer prognosis. Similar biomarkers, to be utilized as surrogates for the assessment of inherited and acquired diseases of the lymphatic circulation, are actively sought, and will represent a signal advance in biomedical investigation.

A model of a radially expanding and contracting lymphangion

The lymphatic system is an extensive vascular network featuring valves and contractile walls that pump interstitial fluid and plasma proteins back to the main circulation. Immune function also relies on the lymphatic system's ability to transport white blood cells. Failure to drain and pump this excess fluid results in edema characterized by fluid retention and swelling of limbs. It is, therefore, important to understand the mechanisms of fluid transport and pumping of lymphatic vessels. Unfortunately, there are very few studies in this area, most of which assume Poiseuille flow conditions. In vivo observations reveal that these vessels contract strongly, with diameter changes of the order of magnitude of the diameter itself over a cycle that lasts typically 2-3s. The radial velocity of the contracting vessel is on the order of the axial fluid velocity, suggesting that modeling flow in these vessels with a Poiseuille model is inappropriate. In this paper, we describe a model of a radially expanding and contracting lymphatic vessel and investigate the validity of assuming Poiseuille flow to estimate wall shear stress, which is presumably important for lymphatic endothelial cell mechanotransduction. Three different wall motions, periodic sinusoidal, skewed sinusoidal and physiologic wall motions, were investigated with steady and unsteady parabolic inlet velocities. Despite high radial velocities resulting from the wall motion, wall shear stress values were within 4% of quasi-static Poiseuille values. Therefore, Poiseuille flow is valid for the estimation of wall shear stress for the majority of the lymphangion contractile cycle.

Sympathetic nerve damage as a potential cause of lymphoedema after axillary dissection for breast cancer

BACKGROUND

The physiological disturbances leading to lymphoedema after breast cancer surgery are poorly understood. Damage to sympathetic nerves during axillary lymph node dissection (ALND), leading to increased capillary fluid filtration, was investigated as a possible contributory factor.

METHODS

The integrity of the upper limb sympathetic nervous system was tested in 36 patients before, and 3 and 12 months after ALND. Forearm vascular resistance (FVR), calculated from forearm blood flow and mean systemic arterial pressure, was measured before and after exposure to lower-body negative pressure. Forearm venous compliance was measured using (99m)Tc-labelled autologous erythrocytes and radionuclide plethysmography before and after cold water immersion of the feet.

RESULTS

There were clear changes in FVR and venous compliance in response to sympathetic stimulation but no differences attributable to surgery or between the nine patients who developed lymphoedema and the 27 who did not; nor were there differences between the two arms. There was a trend towards lower preoperative FVR in patients who developed lymphoedema.

CONCLUSION

Lymphoedema is not the result of sympathetic nerve damage sustained during ALND. Preoperative FVR may help predict who will get lymphoedema following this surgery.

Molecular targets for therapeutic lymphangiogenesis in lymphatic dysfunction and disease

The convergence of multiple disciplines upon the study of the lymphatic vasculature has invigorated a renaissance of research, using powerful investigative tools and an exponential growth of interest in this historically underappreciated system. Fundamental discoveries in lymphatic development have yielded relevant animal models for vexing clinical diseases that suffer from nonexistent of minimally effective treatments. Inherited and acquired lymphedema represent the current crux of research efforts to identify potential molecular therapies born from these early discoveries. The importance of the lymphatic system is, however, not limited to lymphedema but encompasses a diverse spectrum of human disease including inflammation and cancer metastasis. As the lymphatic vasculature continues to benefit from fruits of biomedical investigation, translation of mechanistic insights into targeted, rationally-conceived therapeutics will be become a reality.

Lymphatic drainage in the muscle and subcutis of the arm after breast cancer treatment

Breast cancer-related lymphoedema of the arm (BCRL) results from impaired lymph drainage after axillary surgery. Little is known about lymphatic changes in the arm between surgery and oedema onset. We measured forearm muscle and subcutis lymph drainage in 36 women at 7 and 30 months after surgery by quantitative lymphoscintigraphy. None had BCRL initially but 19% had BCRL by 30 months. At 7 months muscle and subcutis drainage in both arms of BCRL-destined women exceeded that of non-BCRL women (P < 0.01). Muscle lymph drainage always exceeded subcutis drainage (P < 0.0001). Muscle lymph drainage in the ipsilateral arm was unimpaired relative to the contralateral arm. BCRL therefore developed in women with higher peripheral lymph flows. The major lymphatic load was generated by muscle; there was no pre-BCRL lymphatic impairment in the muscle of the ipsilateral arm. We propose that some women have a defined, constitutive predisposition to secondary lymphoedema. Specifically, women with higher filtration rates, and therefore higher lymph flows through the axilla that are closer to the maximum sustainable, are at greater risk of BCRL following axillary trauma, even following removal of 1-2 nodes.

Lymphedema

Aggressively applied decongestive measures (ie, manual lymphatic drainage, low-stretch bandaging, exercise, skin care, application of compressive elastic garments) are the mainstay of lymphatic therapy. Therapeutic regimens should differentiate between the sequential goals of acute volume reduction and maintenance of limb volume. Elastic garments should not be employed until maximal volume reduction has been attained through decongestive lymphatic techniques. It is my opinion that use of intermittent pneumatic compression devices can play an important adjunctive role to decongestive lymphatic therapy but should not be substituted for these techniques. At this time, I am not inclined to use pharmacologic therapy in these patients but anxiously await the results of studies that might demonstrate efficacy for molecular approaches. Surgical intervention is reserved for a small number of well-selected patients. Liposuction for volume reduction appears to be a very promising approach for specific patients.