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We present the case of a 43-year old patient with inguinal lymphadenopathy 22 years after distal femoral resection for osteosarcoma with cemented distal femoral replacement reconstruction. Seven years after initial distal femoral resection patient underwent metal on metal hip resurfacing arthroplasty on the affected side. Twenty years after distal femoral replacement and 13 years after metal on metal hip resurfacing procedure, the patient underwent left inguinal lymph­adenectomy for an enlarged mass of inguinal lymph nodes on suspicion for a sarcoma recurrence. On microscopic ex­amination, excised lymph nodes were massively infiltrated with macrophages and multinucleated giant cells with focal asteroid bodies. An examination in polarized light revealed numerous metal particles; immunohistochemical stainings confirmed reactive character of changes, and florid metal-related sinus histiocytosis was finally diagnosed. Microscopic assessment of lymph nodes in the course of malignancy is a standard procedure; we present a rare case of non-neoplastic lymph node enlargement due to the late onset of metallosis, which might be a diagnostic challenge.

Introduction Malignant peripheral nerve sheath tumor (MPNST) accounts for about 5% of soft tissue sarcomas. It can occur as sporadic diseases or can be associated with type 1 neurofibromatosis. MPNST is usually associated with poor prognosis, mostly due to their aggressive behavior, high metastatic potential, and resistance to chemotherapy. Our study aimed to determine treatment outcomes and associated prognostic factors in a large cohort of patients with MPNSTs treated at the reference sarcoma center. Methods 239 consecutive patients (114 women and 125 men) diagnosed with MPNST between March 1998 and March 2018 who were treated with surgery with curative intent in the reference sarcoma center were included in the retrospective analysis. Results The mean age at diagnosis was 51 years (range 15–86). 28 (11.7%) patients had neurofibromatosis type 1 associated tumors (NF1 positive). Median OS was 126.5 months and 5-year survival rate was 61.9% in the group treated with curative intent. Median DFS, LRFS and DMFS were 91.6, 126.5 and 126.5 months, respectively. We identified tumor size, high tumor grade and positive surgical margins as independent negative predictors of DFS, LRFS, DMFS and OS. Conclusions High-quality surgery remains a gold standard of MPNST treatment. High grade, size and quality of surgery are significant independent prognostic factors for overall survival. There is an unmet need for improvement, especially regarding the perioperative treatment and treatment of metastatic disease. Future studies on the biology of MPNST would lead to the development of novel treatment options and improvement of treatment outcomes.

The data about treatment results of Ewing sarcoma in adult patients are limited. The aim of our study was to analyze prognostic factors and outcomes of therapy in this group of patients. Between 2000 and 2018, 180 patients at the age of > 18 years old diagnosed with Ewing sarcoma were treated in referral center according to multimodal protocols. In 50 patients (28%) treatment was initiated outside our hospital, and 23 of them had started recommended therapy after 3 months since the date of biopsy/unscheduled operation. We analyzed clinical prognostic factors and overall survival (OS). The median age was 28 years (18–67 years), primary tumor was localized axially in 114 patients (63%), metastases at presentation were detected in 51 pts (28%). 5-year OS rate was 65% for patients with localized disease, in metastatic disease it was 15%; the presence and the number of metastases was a prognostic factor. 5-year PFS was significantly better in patients treated at referral center (or when the patients were admitted to referral center within 3 months from the date of biopsy, which was performed outside referral center), comparing to patients treated initially outside referral center; 5-year PFS rates in total population were 28 and 13%, respectively. In terms of OS, unfavorable prognostic factor showing a statistical trend (p = 0.098) was lower dose density of neoadjuvant chemotherapy due to toxicity. Approximately two-third of adult patients with localized Ewing sarcoma survive 5 years. In order to improve survival of this patients the multidisciplinary treatment in referral center is mandatory.

Introduction Osteosarcoma is the most common primary malignant bone tumor in adults and is usually located in long bones. Standard treatment consists of perioperative chemotherapy and radical surgical resection. In the case of the extremity location, the gold standard is limb-sparing surgery (LSS) using a variety of reconstructive techniques. Aim of the study To assess long-term results of adults patients treated for limb osteosarcoma in our referral center depending on the method of surgical treatment. Material and methods In our study, we analyzed 175 adult patients with localized disease (American Joint Committee on Cancer [AJCC] stage I-III) treated for extremity osteosarcoma at our institution between 2000 and 2017. The median observation time was 41 months (3-225 months). 111 patients were treated with LSS (80 patients had tumor resection followed by endoprosthetic reconstruction, 31 patients had local resection without reconstruction) and 64 patients underwent amputation. Results 5-year overall survival (OS) and progression-free survival (PFS) in the study group were 62% and 52% and the life expectancy was on average 136 months. In the group of patients treated with LSS, 5-year OS and PFS were 66% and 59%, respectively, and life expectancy was 147 months, while in the group of patients undergoing amputation 5-year OS, PFS and life expectancy were 55%, 42% and 117 months. Conclusions The best results in the treatment of extremity osteosarcoma were achieved in a group of patients without distant metastases at the time of diagnosis, treated with perioperative chemotherapy and radical resection followed by endoprosthetic reconstruction.

Primary malignant bone tumours, or sarcomas, are rare and represent a major diagnostic and therapeutic challenge. According to the EUROCARE database, they do not exceed 0.2% of all malignancies. According to the American Cancer Society, over 40% of primary bone tumours in adults are chondrosarcomas followed by osteosarcoma (28%), chordoma (10%) Ewing sarcoma (8%), malignant histiocytic sarcoma/fibrosarcoma (4%), and the remaining percentages is distributed among several types of rare bone tumours. In children and adolescents ( < 20 years), osteosarcoma accounts for 56%, Ewing sarcoma 34% and chondrosarcoma only 6%. The best treatment results of bone sarcomas are achieved with the use of combined therapy in highly specialised centres. This combined treatment within specialised multidisciplinary teams gives the patient the greatest chance for appropriate management of their disease and increases their chances to be cured and to avoid disability. Limb sparing surgery is currently a standard in surgical treatment of bone sarcomas. This approach helps to obtain a good functional result and limits the patient’s disability. The most common methods currently used in sparing surgery include modular oncology endoprostheses (megaprostheses), non invasive growing prostheses used in children, bone auto and allografts, rotationplasties, patient specific surgical implants, arthrodesis of large joints, and in some locations only radical bone resections (shoulder, pelvis). In this short review article we present historical and contemporary methods of surgical treatment of primary bone sarcomas.

Background: The presence of tumor-infiltrating lymphocytes (TILs) in many studies is associated with a better prognosis in melanoma patients. Programmed death-ligand 1 (PD-L1) expression has a significant value in predicting several cancers, but its role in melanoma remains ambiguous. The study aims to report a comprehensive analysis of TILs characteristics and their impact on survival in primary acral melanoma (AM). Methods: Clinical and pathological features and survival outcomes were investigated in 70 patients with AM. Immunohistochemical quantitative analysis of TILs, including expression of CD4, CD8, FOXP3, PD-1, and PD-L1, on melanoma cells was performed. Results: Kaplan-Meier analysis showed significant differences in overall survival (OS) for CD4+ (p = 0.021), CD8+ (p = 0.037), FOXP3+ (p = 0.007), and TILs density (p = 0.043). In univariate analysis of immunohistochemical features, FOXP3, CD4, CD8, PD-1, and Melanoma Institute of Australia (MIA) grading TILs (grade, density, and distribution) were correlated with survival. The higher density of FOXP3-positive cells was an independent factor associated with better survival. Conclusions: High TILs content (classed as brisk Clark scale and marked/diffuse TILs MIA grade) regardless of its immunophenotype was associated with better survival outcomes in AM. PD-L1 expression on tumor cells did not influence OS and was independent of clinical and pathological characteristics. We demonstrated that TILs are significant biomarkers in sentinel lymph node status prediction.

Introduction: Myxoid liposarcoma (MLPS) has been reported to be more radiosensitive compared with other soft tissue sarcomas. The main objective of the study was to assess the efficacy of hypofractionated radiotherapy (RT) in the preoperative setting in patients with locally advanced primary MLPS. Methods: Single-arm prospective exploratory clinical trial enrolled MLPS patients for preoperative 5 &times, 5 Gy RT with delayed surgery. The endpoints of the study were the rate of early wound healing complications and 5-year local control rate. Results: 29 patients (pts) were included, all had tumors located on the lower limb. The median maximum size of the tumor was 13 cm (IQR 10&ndash, 15 cm). Early RT tolerance was good. Postoperative wound complications occurred in 11 pts (37.9%), late complications concerned 13.8% of patients. A total of 27 patients were included for the efficacy analyses. The pathological features of response to RT were detected in all analyzed surgical specimens. In 25 patients R0 margins were achieved, two patients had an R1 resection. None of the patients had local recurrence. Conclusion: Preoperative hypofractionated RT with a prolonged gap between RT and surgery is a feasible method of the management of MLPS, providing a good local control and low rates of treatment toxicity.

e21521 Background: Merkel cell carcinoma (MCC) is an uncommon, aggressive neuroendocrine skin cancer. The prognosis in the unresectable and metastatic setting is very poor. Distant metastases develop in more than 30%. Chemotherapy (CHT), the previous mainstay of treatment, is associated with the high response rates (RR) of limited duration. The main cytotoxic drugs have been platinum derivatives, taxoids, anthracyclines, and etoposide. The standard systemic treatment for this disease has changed in the last few years. Immunotherapy (IO) is currently the basis of systemic therapy in the metastatic setting. This study aimed to analyze outcomes for unresectable and metastatic MCC pts treated in routine clinical practice, mostly before the era of IO availability. Methods: We conducted the retrospective analysis of data from 36 MCC pts in unresectable (n= 23) and metastatic (n=13) settings treated in three oncological centers, diagnosed between 01/2010 and 12/2019, with data cut-off on 31/12/2020. The data collected included epidemiological and clinical information. Survival analyses were performed using the Kaplan-Meier method and log-rank test. Results: The median patient age at diagnosis was 72 years (57-88); 58.3% were male. The most common primary tumor (PT) locations were lower limbs (41.7%), head and neck (30.6%), and upper limbs (16.7%). In 63.9% the PT was located in the sun-exposed skin. The most common location of distant metastases were nonregional lymph nodes (n=9) and lungs (n=3). Thirty-six pts received 1st line CHT with the median progression-free survival (mPFS) of 5.3 months (95%CI 2.88-7.7) and objective response of 61.1%, with 13.9% complete responses (CR). The most commonly used regimens were platinum-based and anthracycline-based regimens (n=26). Disease progression (PD) was observed in 91.7% of pts treated with 1st line CHT. Twenty-one pts received 2nd line therapy, IO (n=14), or CHT (n=7), with PD in 19 pts (90.6%), mPFS 2.83 months (95% CI 0.59-5.06) and RR of 33.3% (0% CR). 13 pts were treated with avelumab (AVE), all in the 2nd line, with RR of 38.5% (0% CR). The mPFS in the 2nd line was 5 months (95%CI 0-11.46) on AVE compared to 2.82 (95%CI 0.46-5.19) on CHT (HR 0.65, 95%CI 0.25-1.70, p=0.378). During 1st line systemic therapy, 16 pts underwent palliative surgery (n=7, 19.4%) or received radiation therapy (RT) (n=9, 25%), and during 2nd line, one patient was treated with surgery, and five pts received RT. The median overall survival was 10.38 months (95% CI 2.90-17.87). Local treatment did not improve the treatment outcomes in the 1st (p=0.119) nor 2nd line (p=0.821). Conclusions: Our results confirm the poor prognosis of pts with unresectable and metastatic MCC. The response rates and median PFS for CHT in the 1st and 2nd line setting are consistent with historical data. The treatment with AVE in the 2nd line allows achieving better results, similar to the results reported in the clinical trials.

e21566 Background: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with a high risk of recurrence and poor prognosis. The treatment of locally advanced disease includes surgery (SUR) and radiotherapy (RTH) to achieve high locoregional control rates. The sentinel lymph node biopsy (SLNB) is recommended procedure in cases without clinical nodal involvement. In selected cases, chemotherapy (CHT) may also be considered, but its role is not confirmed. This study aimed to analyze outcomes for locally advanced MCC pts treated in routine clinical practice. Methods: We conducted the retrospective analysis of data from 156 MCC pts treated with curative surgery in four oncological centers, diagnosed between 01/2010 and 12/2019, with data cut-off on 31/12/2020. The data collected included epidemiological and clinical information. Survival analyses were performed using the Kaplan-Meier method, log-rank test and multivariate Cox regression. Results: The median patient age at diagnosis was 72 years (30-94); 50.6% were male. The primary tumor (PT) locations were lower limbs (33.3%), upper limbs (30.1%), and head and neck (28.2%). MCC with no PT was diagnosed in 3.9%. In 62.0% the PT was located in the sun-exposed skin. The median tumor size was 25 mm (4-170). Lymph node (LN) involvement (clinical or positive SLNB or LND) at diagnosis was found in 26.9% (n = 42). The scar excision was done in 50.0% (positive in 16.6%), SLNB in 36.5% (positive in 10.5 %), 51.9% of pts received perioperative treatment, including RTH- 86.4%, CHT- 21%. The relapse rate was 38.3% (35.8% local-regional, 11.1% distant). With the median follow-up of 2.2-years, the median disease-free survival (DFS), local relapse-free survival (LRFS), and distant metastases-free survival (DMFS) were not reached. The 1-year DFS, LRFS and DMFS rates were 65%, 68%, and 90%. The negative independent risk factors for DFS were male gender (HR 1.42, 95%CI 1.06-3.01), metastases in LN at diagnosis (HR 5.41, 95%CI 2.39-12.26), no SLNB in pts with no clinical metastases in LN (HR 5.45, 95%CI 2.41-12.3), and no perioperative RTH (HR 2.19, 95%CI 1.29-3.76). The median overall survival (OS) was 6.9 years (95%CI 4.64-9.15). The negative independent risk factors for OS were male gender (HR 1.95, 95%CI 1.16-3.27), age above 70 (HR 2.0, 95%CI 1.15-3.48), metastases in LN at diagnosis (HR 3.15, 95%CI 1.49-6.68), and no SLNB in pts with no clinical metastases in LN (HR 2.30, 95%CI 1.10-4.82). PT location, UV-exposure, and perioperative CHT or RTH were not independent risk factors for OS. Conclusions: Our results confirm that the MCC treatment should be done in an experienced multidisciplinary team. Male gender, nodal involvement at diagnosis, and no SLNB in pts without clinical metastases in LN are associated with poor prognosis in DFS and OS. The perioperative RTH improves the treatment outcomes and reduces disease progression risk but does not impact OS. Perioperative CHT does not affect pts survival.

Aim of the study : Primary bone tumours are relatively rare, but their diagnosis and treatment is difficult and connected with a high risk of complications. The goal of this report is a retrospective evaluation of outcomes in patients with primary tumours of the humerus treated in our centre with the use of modular endoprosthetic reconstruction. Material and methods : Currently, surgical treatment is a standard procedure for local therapy, with wide tumour-free margin resection after a planned multidisciplinary and individualised strategy of tumour management based on the diagnostic biopsy result. The best option for patients to avoid disability is simultaneous surgical reconstruction aiming to spare the limb and its functionality. Results : In this report, we present the results of treatment of our 11 adult patients suffering from primary bone tumours of the humerus, who have undergone wide bone resection followed by reconstruction with the use of a modular MUTARS® endoprosthesis. Conclusions : The study showed that prosthetic reconstruction of the resected humerus due to a primary bone tumour is safe and acceptable for patients; despite the fact that limitation of active abduction of the shoulder is up to 20 grades, this surgical procedure provides satisfactory limb function.

Background Osteosarcoma is the most common primary malignant bone tumor in adults and is usually located in the long bones. Standard treatment consists of perioperative chemotherapy and radical surgical resection. Limb-sparing surgery using a variety of reconstructive techniques remains the gold standard. Methods In our study, we retrospectively analyzed 90 adult patients operated at our institution between 2000 and 2017 for extremity osteosarcoma that underwent limb-sparing reconstruction with the megaprosthesis. Sixty-one patients underwent resection and reconstruction of the distal femur, 9 patients—proximal femur, 7 patients—proximal tibia, 5 patients—total femoral resection and reconstruction, 5 patients—proximal humeral resection, and 3 patients—other types of resection with endoprosthetic reconstruction. The median follow-up time was 41 months, median overall survival was 86 months (3–225 months), and progression-free survival was 81 months (1–86 months). Functional assessment was made on 48 out of 56 living patients, after endoprosthetic reconstruction. The assessment was made according to MSTS functional scale. Results In 14 cases (15%), the endoprosthesis had to be explanted, or amputation was performed for local recurrence or septic complication. Due to a mechanical failure of the implant, we had to perform a revision in 5 patients (5%). Eighteen out of 74 patients with endoprosthesis died of the disease. The median MSTS score was 84% (53–100%), and the best result of 85% was achieved in patients after distal femoral resection with endoprosthetic reconstruction. Conclusion Careful planning of the treatment of patients with extremity osteosarcoma that is performed at the referral centers gives the possibility of long-term survival with a good and excellent functional result.

Giant cell tumor of bone (GCTB) is an osteolytic, locally aggressive tumor that rarely metastasizes and typically occurs in the bones. At present, the primary treatment for GCTB is curettage with local adjuvants. Giant cells express receptor activator of nuclear factor-κB ligand (RANKL). Denosumab, a RANKL inhibitor appears to present an effective therapeutic option in advanced cases of GCTB. The aim of the present study was to confirm the efficacy of denosumab in large group of patients with locally advanced GCTB. A total of 35 patients with histologically confirmed GCTB that were treated with denosumab with no participation in clinical trials between May 2013 and September 2015 were included in the present study. Denosumab treatment was administered until complete tumor resection was feasible or tumor progression or unacceptable toxicity had occurred. The mean denosumab treatment duration was 7.4 months. A total of 17 patients received surgery following denosumab treatment: 11 patients underwent wide en bloc resection with prosthesis implantation in 10 cases and 6 patients were treated with intralesional curettage. Tumor progression was observed in 2 patients that underwent intralesional curettage without prosthesis implantation. In addition, tumor progression was observed during denosumab treatment in 2 patients that had previously undergone radiotherapy. The overall 1-year progression-free survival rate was 92.8%. Thus, for patients with advanced, unresectable, progressive or symptomatic pretreated GCTB, denosumab provides a therapeutic option not previously available, which has become the standard therapy in multidisciplinary management of GCTB.

11555 Background: Soft tissue sarcomas (STS) are rare often malignant tumors. The primary treatment of most STS is radical resection with adjuvant radiotherapy. Our previous study showed that the use of preoperative hypofractionated radiotherapy is safe and efficient in the treatment of unselected group of patients with STS. Aim of this study was to assess the use of the treatment scheme in patients with primary STS treated in one institution. Methods: 311 patients (52% female) with primary locally advanced STS participated in this prospective trial conducted from 2010 till 2017. Median age was 55 years (range: 17-91). Median follow up is 57 months (95%CI 55-61). The most common subtypes were pleomorphic sarcoma, liposarcoma and synovial sarcoma. Median tumor size was 11cm. 258 patients (83%) had high grade tumors. The most common tumor localization were lower limbs (72%). 30% of patients received preoperative chemotherapy. For five consecutive days radiotherapy in 5 x 5Gy fraction was applied, with immediate (2-4 days) resection of the tumor. Results: In 260 patients (83.6%) clear surgical margins (R0) were obtained. 107 patients were dead at the time of the analysis.5-year overall survival is 63%. 156 (50%) had a recurrence of the disease. Local recurrence (LR) was found in 13.8% of the patients. Median time from surgery to LR was 14.7 months. In 56% of patients with LR another limb spearing radical surgery could be performed. Factors that had a significant adverse impact on LR were histological subtype (p = 0.017) and surgical margin status (p = 0.013). Factors that had a significant adverse impact on overall survival were tumor size (p < 0.0001), grade (p = 0.0047) and surgical margin status (p = 0.013). 96 patients (30.8%) had any kind of treatment toxicity, factor having negative impact on the toxicity was lower limb location of the tumor (p = 0.0012). 20 patients (6.4%) required surgery for treatment of the complications. 14.6% patients had prolonged healing of the wound ( > 1 month), 8.3% had wound dehiscence, 1.4% required prolonged punctures of the lymph fluid, 2.3% had severe fibrosis leading to contracture of limb, 11% patients prolonged edema of the operated limb. 0.9% of patients had a fracture of the treated limb. Conclusions: In this group, with a big percentage of patients with large, high grade STS use of hypofractionated preoperative radiotherapy was associated with similar local control when compared to published studies. The early toxicity is tolerable, with a small amount of late complications.

e22529 Background: Data from many studies in cancer studies suggest that factors such as expression of PD-L1, tumor infiltrating lymphocytes (TILs) and high mutational burden (TMB) in the tumor cells are connected with better response to immune check-point blockage and may have prognostic value. Little is known about those factors in other neoplasms. Methods: In this retrospective study, we have included 31 patients with leiomyosarcoma (LMS) localized on extremity (21) or in retroperitoneal space (10) treated in our center between 2002-2018 with available biopsy specimens obtained before treatment. Mean age was 58 year (SD: 17). Male:Female ratio was 0.82. 14(45%) lesions were deemed high-grade sarcomas. 3 patients had metastases at the time of diagnosis. Immunohistological assays for TILs, tumor associated macrophages (TAMs), PD-1 and PD-L1. TMB was assessed in Tumor Mutational Burden Panel in the formalin-fixed paraffin-embedded samples. 7 cases were excluded from TMB analysis due to poor specimens quality. Fisher exact test was used to compare discrete variables while Kaplan-Meier estimate and stratified log-rank test were used to examine impact of explored factors on survival. Results: The median overall survival in this cohort was 33.4 months (95% confidence intervals, CI: 32-NA). TMB > = 10 mutations/Mb was present in 33% high-grade (HG) and in 25% cases of low-grade (LG) LMS (p = 0.067). PD-L1 expression was present in 54% of HG lesions and in 31% of LG LMS (p = 0.43). TILs and TAMs were highly correlated and present in 40% and 50% of HG LMS and LG LMS respectively (p = 0.722). Among explored factors only TILs and TAMs had significant influence on survival as deemed by log-rank test stratified by tumor grade (p = 0.004) with 3-year survival rate of 100% in groups without TILs/TAMs regardless of grade and 0% in HG TILs/TAMs(+) group and 60% (95% CI: 31-100%) in LG TILs/TAMs(-) group. Conclusions: Significant percentage of LMS exhibit immunohistological and molecular traits which potentially are connected with good response to check-point blockage agents. The immunological infiltration of primary LMS may be strong negative prognostic factor, what is interesting in sarcoma. Future expansion of this study cohort is warranted.

The study presented two cases of synchronous occurrence of colon and appendiceal adenocarcinoma. Both patients required surgical intervention, due to acute peritonitis during the course of acute appendicitis. In case of one patient we performed abdominal CT confirming the presence of sigmoid cancer. The patient was subjected to appendectomy and Hartmann's operation. The second patient underwent an appendectomy, and colonoscopy performed two months later revealed the presence of rectal adenocarcinoma. The patient was subjected to low anterior rectal resection. The histopathological results considering both patients revealed the presence of synchronous colon and appendiceal adenocarcinoma.

Background The sentinel lymph node biopsy (SLN) is a basic staging method in all primary cutaneous melanomas ≥pT1b. The standard technique is a triple technique consisting of preoperative lymphoscintigraphy, intraoperative blue-dye lymphography, and gamma-probe assessment. We performed the analysis of long-term results in a very large one-institution series of cutaneous melanoma patients. Methods We have analyzed treatment results of a group of 1764 consecutive patients with cutaneous melanoma, who underwent SLN biopsy between 1997 and 2008 in one tertiary center. Additionally, we have analyzed the outcomes of a group of 473 patients with positive SLN biopsy undergoing completion lymph node dissection (CLND). Median follow-up time was 5.3 years. Results Metastases to SLN (SLN+) were found in 19.9 %. Eight-year overall survival (OS) rate in the entire group was 73.5 %, 80 % without SLN metastases (SLN−) and 50 % in group with SLN+ (p 5/mm2) of primary tumor. The nodal recurrences in the biopsied lymphatic basin were 5.4 %. The metastases to non-sentinel lymph nodes (NSLN found in 27 % of patients with SLN+) correlated (on multivariable logistic regression analysis) with primary tumor thickness >4 mm, SLN metastatic deposit size >1 mm, and extracapsular involvement of SLN. In an additionally analyzed SLN+ group, the NSLN involvement was related to poorer prognosis (8-year OS rate NSLN− vs NSLN+: 59.6 vs. 34.7 %, respectively). The independent prognostic factors for OS in the SLN+ group were a higher Breslow thickness and ulceration of primary tumor, metastases to more than 1 lymph nodes. Conclusions The long-term results confirm crucial prognostic significance of SLN biopsy in cutaneous melanoma. We identified factors related to NSLN involvement, which in the future may limit indications for CLND.