Risks For Multiple Lymph Node Metastasis Or Non-sentinel Lymph Node Metastasis In Breast Cancer

Background and objectiveThe sentinel lymph node(SLN)is t he first lymph node to receive lymphatic drainage from a tumor and theoretically the first site of lymphatic metastasis.The results of the American College of Surgeons Oncology Group(ACOSOG)Z0011 trial show that patients with 1-2 positive SLN may avoid axillary lymph node dissection(ALND).However,patients eligible for Z0011 but at a higher risk of residual nodal disease may benefit from ALND.Hence,how to find patients in high risk for non-SLN metastasis could still be valuable in decision making regarding completion ALND in 1-2 SLNs positive patients.The number of negative SLNs has been identified as an independent predictor of non-SLN metastasis.Hence,it is important to clarify whether the identification of more SLNs is beneficial.Accordingly,the objective of this study was to determine how many SLNs are needed to predict non-SLN metastasis in patients with breast cancer.Lymph node metastasis is one of the most important prognostic factors for breast cancer.In light of the complexity of metastasis itself,we need to more deeply explore its molecular mechanism including preclinical and clinical aspects.We will investigate the molecular risk factors for lymph node metastasis according to RNA-Sequence analysis for patients with clinicopathologic risk factors screened before.Patients and methodsPart1 Risk factors for 3 or more lymph nodes metastasis of breast cancerPatients with pT1-2N1-3M0 breast cancer underwent ALND in our hospital were included in this study.They were divided into 2 groups:group of patients with one or two lymph nodes metastasis and group of patients with 3 or more lymph nodes metastasis.The clinicopathological characteristics,including age,tumor size,presence of multiple lesions,presence of lymphovascular invasion(LVI),hormone receptor status,HER2/neu status and Ki67 were analyzed retrospectively.Part 2 Study of non-sentinel lymph node metastasisPatients with stage cT1-2N0M0 breast cancer who underwent SLNB in our hospital were included in the present study.Clinicopathological characteristics,including age,tumor size,presence of multiple lesions,presence of lymphovascular invasion,number of positive SLNs,number of negative SLNs,hormone receptor status,HER2/neu status and Ki67 were analyzed and scored.Lymphatic mapping for SLNB was performed using blue dye.Patients underwent ALND or no further axillary treatment according to guideline and their will.Association between number of positive/negative SLNs and non-SLN metastasis was investigated.Risk factors for non-sentinel lymph node metastasis was investigated and scored in breast cancer patients with 1-2 sentinel lymph nodes metastasis.Part 3 Investigate the mechanism of lymph node metastasis by RNA-SequenceLarge tumor size,presence of lymphovascular invasion and HER2 over express were detected as risk factors for lrymph node metastasis in our previous study.Four breast cancer patients who underwent modified radical mastectomy in our hospital were included.Two patients had a high risk of lymphatic metastasis,lymphatic metastasis did not occur;whereas,two patients had a low risk of lymphatic metastasis,lymphatic metastasis did occur.Total RNA from breast cancer tissue and adjacent normal tissue was extracted by TRIzol.The LIMMA package in R language,a liner regression model,was used to identify the DEGs in breast tissue and adjacent tissue.GO and KEGG were used to perform the functional analysis of DEGs.The PPI networks in the present study were constructed using Cytoscape.ResultsPart1 Risk factors for 3 or more lymph nodes metastasis of breast cancer453 patients had one or two lymph node metastasis while 350 patients had 3 or more lymph node metastasis.Base on the results of the multivariate analysis,large tumor size,present of lymphovascular invasion,HER-2 positive were identified as independent predictors of 3 or more axillary lymph nodes metastasis.Part 2 Study of non-sentinel lymph node metastasisIn total,723 patients with stage cT1-2N0M0 breast cancer underwent SLNB.472 patients underwent ALND.In total,56.4%of the SLNB findings were negative.In all patients with positive SLNs,73.8%had only one positive SLN,20.5%had two positive SLNs,and 5.6%had three or more positive SLNs.A large tumor size,SLN positivity,and HER-2 positivity were independent predictors of non-SLN metastasis.Presence of positive SLNs and absence of negative SLNs were significant risks for non-SLN metastasis.However,there was no significant difference between the amount of SLNs(>0)and non-SLN metastasis.251 patients did not underwent ALND.No patients developed recurrence in the axilla.215 patients with one or two sentinel lymph node metastasis were analyzed.By Multivariate analysis,large tumor size,negative SLN<1,present of lymphovascular invasion,HER-2 positive were independent risk factors of non-SLN metastasis.33 patients were considered as "high risk" for non-SLN metastasis,in whom P>0.5.30 patients(90.9%)of them had NSLN metastasis actually.Part 3 Investigate the mechanism of lymph node metastasis by RNA-SequenceThe DEGs in HRNM_T(Tumor of patients with high risk of lymph node metastasis)versus HRNM_N(Normal tissue of patients with high risk of lymph node metastasis)were enriched in multiple GO categories,mainly the cell cycle,the IL-17 signaling pathway,and the progesterone-mediated oocyte maturation.The DEGs in LRYM_T(Tumor of patients with low risk of lymph node metastasis)versus LRYM_N(Normal tissue of patients with low risk of lymph node metastasis)were enriched mainly in protein digestion and absorption,cytokine-cytokine receptor interaction and ECM-receptor interaction.The DEGs in HRNM_T versus LRYM_T were enriched mainly in the PPAR signaling pathway and the adipocytokine signaling pathwayConclusionsALND is recommended for patients with high risk of non-SLN involvement,even if they met the Z0011 criteria.For other patients,ALND would be avoided if they meet the Z0011 criteria.The number of SLNs obtained should be appropriate.The presence of one negative SLN is enough in SLN biopsy.In consideration of the injury of the surgery,two or more negative SLNs may be unnecessary.The GO and KEGG functional enrichments of HRNM T versus HRNM N,and LRYM T versus LRYM N were consistent with earlier studies.For HRNM_T versus LRYM T,DEGs were up-regulated mainly in PPAR signaling;DEGs were down-regulated mainly in the adipocytokine pathway.