Recent Advances in Therapeutic Modalities Against Breast Cancer-Related Lymphedema: Future Epigenetic Landscape.

Background: Lymphedema is a significant postsurgical complication observed in the majority of breast cancer patients. These multifactorial etiopathogenesis have a significant role in the development of novel diagnostic/prognostic biomarkers and the development of novel therapies. This review aims to ascertain the epigenetic alterations that lead to breast cancer-related lymphedema (BCRL), multiple pathobiological events, and the underlying genetic predisposing factors, signaling cascades pertinent to the lapses in effective prognosis/diagnosis, and finally to develop a suitable therapeutic regimen. Methods and Results: We have performed a literature search in public databases such as PubMed, Medline, Google Scholar, National Library of Medicine and screened several published reports. Search words such as epigenetics to induce BCRL, prognosis/diagnosis, primary lymphedema, secondary lymphedema, genetic predisposing factors for BRCL, conventional therapies, and surgery were used in these databases. This review described several epigenetic-based predisposing factors and the pathophysiological consequences of BCRL, which affect the overall quality of life, and the interplay of these events could foster the progression of lymphedema in breast cancer survivors. Prognosis/diagnostic and therapy lapses for treating BCRL are highly challenging due to genetic and anatomical variations, alteration in the lymphatic vessel contractions, and variable expression of several factors such as vascular endothelial growth factor (VEGF)-E and vascular endothelial growth factor receptor (VEGFR) in breast cancer survivors. Conclusion: We compared the efficacy of various conventional therapies for treating BCRL as a multidisciplinary approach. Further substantial research is required to decipher underlying signaling epigenetic pathways to develop chromatin-modifying therapies pertinent to the multiple etiopathogenesis to explore the correlation between the disease pathophysiology and novel therapeutic modalities to treat BCRL.

Genetic Predisposition in Cancer-Related Lymphedema: A Systematic Review.

Background: Lymphedema is a debilitating and progressive clinical entity characterized by abnormal accumulation of lymph and fluid in the extracellular space. Most of the cases in western population are related to cancer treatment. Research on cancer-related lymphedema (CRL) is mounting for potential risk factors associated to disease, treatment, or patient. However, only a few cancer survivors with the same risk factors will develop lymphedema, giving rise to the hypothesis that inherited genetic susceptibility may play a role in CRL pathophysiology. This systematic review aimed to identify, critically appraise, and summarize the results of individual studies that have examined the genetic predisposition to CRL. Methods and Results: A comprehensive literature search in MEDLINE, Cochrane, and Scopus was conducted from inception to February 2021. Screening of available studies and quality of the included studies were carried out by two reviewers independently. Eight studies fulfilled eligibility criteria, involving 573 women with breast-cancer related lymphedema (BCRL) among 1,481 participants. Associations between the development of CRL and genetic factors were observed for variations in 23 genes in patients with BCRL. Conclusions: The present systematic review is the first examining specifically the genetic predisposition in CRL. Statistically significant genetic variations were found in 23 genes in patients with BCRL. These preliminary findings highlight the importance of genetic susceptibility in the development of CRL, altering the traditional perception of its iatrogenic etiology. Additional well-designed research, aiming toward the confirmation of previously performed genetic analyses and functional assessment of the genetic variations, is required.

Lymphedema alters lipolytic, lipogenic, immune and angiogenic properties of adipose tissue: a hypothesis-generating study in breast cancer survivors.

Later stages of secondary lymphedema are associated with the massive deposition of adipose tissue (AT). The factors driving lymphedema-associated AT (LAT) expansion in humans remain rather elusive. We hypothesized that LAT expansion could be based on alterations of metabolic, adipogenic, immune and/or angiogenic qualities of AT. AT samples were acquired from upper limbs of 11 women with unilateral breast cancer-related lymphedema and 11 healthy women without lymphedema. Additional control group of 11 female breast cancer survivors without lymphedema was used to assess systemic effects of lymphedema. AT was analysed for adipocyte size, lipolysis, angiogenesis, secretion of cytokines, immune and stem cell content and mRNA gene expression. Further, adipose precursors were isolated and tested for their proliferative and adipogenic capacity. The effect of undrained LAT- derived fluid on adipogenesis was also examined. Lymphedema did not have apparent systemic effect on metabolism and cytokine levels, but it was linked with higher lymphocyte numbers and altered levels of several miRNAs in blood. LAT showed higher basal lipolysis, (lymph)angiogenic capacity and secretion of inflammatory cytokines when compared to healthy AT. LAT contained more activated CD4+ T lymphocytes than healthy AT. mRNA levels of (lymph)angiogenic markers were deregulated in LAT and correlated with markers of lipolysis. In vitro, adipose cells derived from LAT did not differ in their proliferative, adipogenic, lipogenic and lipolytic potential from cells derived from healthy AT. Nevertheless, exposition of preadipocytes to LAT-derived fluid improved their adipogenic conversion when compared with the effect of serum. This study presents results of first complex analysis of LAT from upper limb of breast cancer survivors. Identified LAT alterations indicate a possible link between (lymph)angiogenesis and lipolysis. In addition, our in vitro results imply that AT expansion in lymphedema could be driven partially by exposition of adipose precursors to undrained LAT-derived fluid.

Race/ethnicity, genetic ancestry, and breast cancer-related lymphedema in the Pathways Study.

Breast cancer-related lymphedema (BCRL) is a serious chronic condition after breast cancer (BC) surgery and treatment. It is unclear if BCRL risk varies by race/ethnicity. In a multiethnic prospective cohort study of 2953 BC patients, we examined the association of self-reported BCRL status with self-reported race/ethnicity and estimated genetic ancestry. Hazard ratios (HR) and 95 % confidence intervals (CI) were calculated by multivariable Cox proportional hazards models, with follow-up starting 6 months post-BC diagnosis. Estimates were further stratified by body mass index (BMI). By 48 months of follow-up, 342 (11.6 %) women reported having BCRL. Younger age at BC diagnosis, higher BMI at baseline, and lower physical activity were associated with greater BCRL risk. African American (AA) women had a 2-fold increased risk of BCRL compared with White women (HR = 2.04; 95 % CI 1.35-3.08). African genetic ancestry was also associated with an increased risk (HR = 2.50; 95 % CI 1.43, 4.36). Both risks were attenuated but remained elevated after adjusting for known risk factors and became more pronounced when restricted to the nonobese women (adjusted HR = 2.31 for AA and HR = 3.70 for African ancestry, both p < 0.05). There was also evidence of increased BCRL risk with Hispanic ethnicity in the nonobese women. Nonobese AA women had a higher risk of BCRL than White women, which cannot be fully explained by known risk factors. This is the first large-scale, prospective study demonstrating differences in BCRL risk according to race/ethnicity as assessed by both self-report and genetic ancestry data, with a potential ancestry-obesity interaction.

Precision assessment of heterogeneity of lymphedema phenotype, genotypes and risk prediction.

Lymphedema following breast cancer surgery is considered to be mainly due to the mechanical injury from surgery. Recent research identified that inflammation-infection and obesity may be the important predictors for lymphedema. The purpose of this exploratory research was to prospectively examine phenotype of arm lymphedema defined by limb volume and lymphedema symptoms in relation to inflammatory genes in women treated for breast cancer. A prospective, descriptive and repeated-measure design using candidate gene association method was used to enroll 140 women at pre-surgery and followed at 4-8 weeks and 12 months post-surgery. Arm lymphedema was determined by a perometer measurement of ≥5% limb volume increase from baseline of pre-surgery. Lymphedema symptom phenotype was evaluated using a reliable and valid instrument. Saliva samples were collected for DNA extraction. Genes known for inflammation were evaluated, including lymphatic specific growth factors (VEGF-C & VEGF-D), cytokines (IL1-a, IL-4, IL6, IL8, IL10, & IL13), and tumor necrosis factor-a (TNF-a). No significant associations were found between arm lymphedema phenotype and any inflammatory genetic variations. IL1-a rs17561 was marginally associated with symptom count phenotype of ≥8 symptoms. IL-4 rs2070874 was significantly associated with phenotype of impaired limb mobility and fluid accumulation. Phenotype of fluid accumulation was significantly associated with IL6 rs1800795, IL4 rs2243250 and IL4 rs2070874. Phenotype of discomfort was significantly associated with VEGF-C rs3775203 and IL13 rs1800925. Precision assessment of heterogeneity of lymphedema phenotype and understanding the biological mechanism of each phenotype through the exploration of inherited genetic susceptibility is essential for finding a cure. Further exploration of investigative intervention in the context of genotype and gene expressions would advance our understanding of heterogeneity of lymphedema phenotype.