Laparoscopic mesh removal for chronic postoperative inguinal pain following endoscopic hernia repair: a cohort study on the effect on pain.

PURPOSE: Chronic postoperative inguinal pain (CPIP) after pre-peritoneal hernia repair is rare but may be severely invalidating. Mesh may be a contributing factor to the development of CPIP. International guidelines acknowledge mesh removal as a treatment option for CPIP after open repair, but experience in laparoscopic mesh removal is limited. Surgeons are hesitant to remove pre-peritoneal meshes because of fear of operative complications. This observational study describes risks and effectiveness of laparoscopic mesh removal in patients with CPIP after endoscopic inguinal hernia repair. METHODS: Questionnaires and operative findings of consecutive patients undergoing a laparoscopic mesh removal for CPIP between August 2014 and February 2019 in the center for groin pain were prospectively recorded. Long-term efficacy was determined using pre and postoperative questionnaires on pain and quality of life. RESULTS: Forty-four patients were included (37 males, median age 51 years). Complete or sufficient pain relief was reported in every two out of three patients (68%) and quality of life improved significantly. Intraoperative findings included wrinkled mesh (n = 19), meshoma (n = 14) and infected mesh (n = 1). Surprisingly, over half of the meshes (n = 23) did not fully cover the groin, with three clear recurrent hernias. Intraoperative complications included two bladder injuries. One patient undergoing removal of 3 meshes on one side developed a necrotic testicle. During follow-up, three patients developed a recurrent hernia requiring open surgery. CONCLUSION: Laparoscopic mesh removal is safe and effective in selected patients with CPIP after endoscopic hernia repair. We believe that this technique should be adopted by dedicated hernia surgeons.

Recall bias in pain scores evaluating abdominal wall and groin pain surgery.

PURPOSE: To determine whether levels of pre-operative pain as recalled by a patient in the post-operative phase are possibly overestimated or underestimated compared to prospectively scored pain levels. If so, a subsequent misclassification may induce recall bias that may lead to an erroneous effect outcome. METHODS: Data of seven retrospective cohort studies on surgery for chronic abdominal wall and groin pain using three different pain scores were systematically analyzed. First, it was assessed whether retrospectively acquired pre-operative pain levels, as scored by the patient in the post-operative phase, differed from prospectively obtained pre-operative pain scores. Second, it was determined if errors associated with retrospectively obtained pain scores potentially lead to a misclassification of treatment outcome. Third, a meta-analysis established whether recall misclassifications, if present, affected overall study conclusions. RESULTS: Pain data of 313 patients undergoing remedial surgery were evaluated. The overall prevalence of misclassification due to a recall error was 13.7%. Patients not benefitting from surgery ('failures') judged their pre-operative pain level as more severe than it actually was. In contrast, patients who were pain free after remedial surgery ('successes') underestimated pre-operative pain scores. Recall misclassifications were significantly more present in failures than in successful patients (odds ratio 2.4 [95% CI 1.2-4.8]). CONCLUSION: One in seven patients undergoing remedial groin surgery is misclassified on the basis of retrospectively obtained pre-operative pain scores (success instead of failure, or vice versa). Misclassifications are relatively more present in failures after surgery. Therefore, the effect size of a therapy erroneously depends on its success rate.

Role Of Ovarian Metastases In Colorectal Cancer (ROMIC): a Dutch study protocol to evaluate the effect of prophylactic salpingo-oophorectomy in postmenopausal women.

BACKGROUND: The mean incidence of ovarian metastases (OM) in patients with colorectal cancer (CRC) is 3.4%. The 5-year survival of these patients, even when operated with curative intent, is remarkably low. The lifetime risk of ovarian cancer is approximately 1.3%. Prophylactic salpingo-oophorectomy (PSO, or surgical removal of the ovaries and fallopian tubes) could reduce the number of CRC patients that develop OM after removal of the primary tumor, as well as preventing the occurrence of primary ovarian cancer. Recently, the care pathway for CRC has been changed in several hospitals in line with the updated Dutch guideline. The possibility of PSO is now discussed with postmenopausal CRC patients in these hospitals. The aims of the current study are firstly to estimate the incidence of OM and primary ovarian cancer in postmenopausal patients with CRC, and secondly to evaluate the effect of PSO in these patients. METHODS: An information bulletin and decision guide on this topic was implemented in several Dutch hospitals in 2020. Post-decision outcomes will be collected prospectively. The study population consists of postmenopausal (≥ 60 years of age) patients that are operated with curative intent for CRC. Based on their own preference, patients will be divided into two groups: those who choose to undergo PSO and those who do not. The main study parameters are the reduction in incidence of ovarian malignancies (metastatic or primary) following PSO, and the number needed to treat (NNT) by PSO to prevent one case of ovarian malignancy. DISCUSSION: This will be the first study to evaluate the effect of PSO in postmenopausal CRC patients that is facilitated by an altered CRC care pathway. The results of this study are expected to provide relevant information on whether PSO adds significant value to postmenopausal patients with CRC. TRIAL REGISTRATION: International Clinical Trials Registry Platform, NL7870. Registered on 2019 July 12. URL of trial registry record: https://trialsearch.who.int/Trial2.aspx?TrialID=NL7870 . PROTOCOL VERSION: 1.0, date 2021 June 8.

Ovarian metastases in young women with colorectal cancer: a retrospective multicenter cohort study.

BACKGROUND AND PURPOSE: Previous studies indicated that approximately 3.4% of female colorectal cancer (CRC) patients are at increased risk of developing ovarian metastases (OM). It has been suggested that young women more frequently develop this form of metastatic disease. METHODS: This study evaluated, in 6 Dutch hospitals, the proportion of young women with CRC who developed OM. RESULTS: In a cohort of 200 young (age ≤ 55) women with CRC, the proportion of patients diagnosed with synchronous or metachronous OM was calculated. This study revealed that 5% (n = 10) of young female CRC patients developed ovarian metastases resulting in a 5-year overall survival rate of approximately 40%. Furthermore, six patients had concurrent peritoneal metastases, five patients had bilateral ovarian metastases, and five patients had synchronous metastases, while the median time of the occurrence of metachronous metastases (n = 5) was 19 months. CONCLUSION: This retrospective multicenter cohort study indicates that 5% of young women with CRC either present with or develop OM. This result appears to be clinically relevant and demonstrates the need for improved surveillance for young women diagnosed with CRC.

Primary ovarian cancer after colorectal cancer: a Dutch nationwide population-based study.

BACKGROUND AND PURPOSE: Women with colorectal cancer (CRC) are at risk not only of developing ovarian metastases, but also of developing a primary ovarian malignancy. Several earlier studies have in fact shown a link between the development of primary ovarian cancer and CRC. The purpose of this study was therefore to determine the risk of developing a primary ovarian cancer in women with prior CRC compared to the general population. METHODS: Data from the Netherlands Cancer Registry were used. All women diagnosed with invasive CRC between 1989 and 2017 were included. Standardized incidence ratios (SIRs) and absolute excess risks (AERs) per 10,000 person-years were calculated. RESULTS: During the study period, 410 (0.3%) CRC patients were diagnosed with primary ovarian cancer. Women with CRC had a 20% increased risk of developing ovarian cancer compared to the general population (SIR = 1.2, 95% CI: 1.1-1.3). The AER of ovarian cancer was 0.9 per 10,000 person-years. The risk was especially increased within the first year of a CRC diagnosis (SIR = 3.3, 95% CI: 2.8-3.8) and in women aged ≤ 55 years (SIR = 2.0, 95% CI: 1.6-2.6). CONCLUSION: This study found a slightly increased risk of primary ovarian cancer in women diagnosed with CRC compared to the general population. However, this may be partly attributable to surveillance or detection bias. Nevertheless, our findings could be helpful for patient counseling, as CRC patients do not currently receive information concerning the increased risk of ovarian cancer.

Are polypropylene mesh implants associated with systemic autoimmune inflammatory syndromes? A systematic review.

PURPOSE: The surgical implantation of polypropylene (PP) meshes has been linked to the occurrence of systemic autoimmune disorders. We performed a systematic review to determine whether PP implants for inguinal, ventral hernia or pelvic floor surgery are associated with the development of systemic autoimmune syndromes. METHODS: We searched Embase, Medline, Web of Science, Scopus, Cochrane library, clinicaltrialsregister.eu, clinicaltrails.gov and WHO-ICTR platform. Last search was performed on November 24th 2021. All types of studies reporting systemic inflammatory/autoimmune response in patients having a PP implant for either pelvic floor surgery, ventral or inguinal hernia repair were included. Animal studies, case reports and articles without full text were excluded. We intended to perform a meta-analysis. The quality of evidence was assessed with the Newcastle-Ottawa Scale. This study was registered at Prospero (CRD42020220705). RESULTS: Of 2137 records identified, 4 were eligible. Two retrospective matched cohort studies focused on mesh surgery for vaginal prolapse or inguinal hernia compared to hysterectomy and colonoscopy, respectively. One cohort study compared the incidence of systemic conditions in women having urinary incontinence surgery with and without mesh. These reports had a low risk of bias. A meta-analysis showed no association when comparing systemic disease between mesh and control groups. Calculated risk ratio was 0.9 (95% CI 0.82-0.98). The fourth study was a case series with a high risk of bias, with a sample of 714 patients with systemic disease, 40 of whom had PP mesh implanted. CONCLUSION: There is no evidence to suggest a causal relationship between being implanted with a PP mesh and the occurrence of autoimmune disorders.

Factors related to patient-reported cosmetic outcome after breast-conserving therapy for breast cancer.

BACKGROUND: Multiple factors can affect cosmetic outcome after breast-conserving therapy. We investigated which combination of factors could optimally predict patient reported cosmetic outcome. METHODS AND MATERIALS: Dutch patients treated with BCT between 2008 and 2013 were retrospectively analysed. Demographics, tumour characteristics, and treatment-related factors were obtained from available digital medical records. Patients were asked to indicate their degree of cosmetic satisfaction using the Harvard scale. Both univariable and multivariable logistic regression analyses were performed to create a prediction model. RESULTS: The present study based on 220 patients shows that univariable analysis radiotherapy boost (OR 4.01 [1.85-8.70], p ≤ 0.001) and adjuvant chemotherapy (OR 2.67 [1.45-4.92], p = 0.002) were significantly associated with unsatisfactory cosmetic outcome. In multivariable analyses, only a radiotherapy boost remained significantly associated (OR 4.08 [1.76-9.49], p = 0.001) with poor cosmetic outcome, while adjuvant chemotherapy was no longer associated with it (OR 1.61 [0.81-3.24), p = 0.18). These two factors, together with tumour histology and lymph node staging, showed the highest predictive values, although the predictive property of the overall model was limited (AUC = 0.69). CONCLUSION: In the present study, a variety of factors is explored. However, a radiotherapy boost was the only factor that was independently associated with a poor cosmetic outcome after BCT. This finding can be used for counselling in daily clinical practice. Creation of a prediction model will require further investigation.

Breast cancer patient-reported outcome of factors influencing cosmetic satisfaction after breast-conserving therapy.

BACKGROUND: The aim of this study was to investigate which factors patients considered to be important for determining the degree of cosmetic satisfaction with regards to perceived body image after previous breast-conserving therapy (BCT). METHODS: Outcomes considered relevant by the patients were first identified using interviews. A questionnaire based on this group input was then devised and added to the physician-based Sneeuw questionnaire. Next, a quantitative study using this questionnaire was conducted in Dutch patients treated at least 6 months earlier for (non-) invasive breast cancer by BCT. Exclusion criteria were: previous mastectomy or BCT of the contralateral breast, BCT with nipple resection, metastatic disease, local recurrence or (previous) plastic breast surgery. Descriptive statistics were used throughout. RESULTS: A total of 149 patients (aged 36-87 years) completed the questionnaire. From this focus group input, the top three factors in overall importance (important or very important) for satisfaction were: 'wearability of bra' (67%), 'breast sensitivity' (59%) and 'asymmetry' (51%). Younger patients (< 55 years) considered 'breast size' to be most important, whereas 'wearability of bra' was most frequently reported by older patients (> 55 years). Time since BCT did not significantly influence the rating of relevant factors. CONCLUSION: Patients consider 'wearability of bra', 'breast sensitivity' and 'asymmetry' as the most important factors when assessing their satisfaction with regards to cosmetic outcome and body image. These factors should be addressed in routine clinical practice during (pre) counseling.

Metabolic syndrome; associations with adverse outcome after colorectal surgery. A systematic review and meta-analysis.

BACKGROUND: Increasing evidence shows that patients with Metabolic Syndrome (MetS) are at risk for adverse outcome after abdominal surgery. The aim of this study was to investigate the impact of MetS and preoperative hyperglycemia, as an individual component of MetS, on adverse outcome after colorectal surgery. METHODS: A literature review was systematically performed according to the PRISMA guidelines. Inclusion criteria were observational studies that evaluated the relationship between MetS or preoperative hyperglycemia and outcomes after colorectal surgery (i.e. any complication, severe complication defined as Clavien-Dindo grade ≥ III, anastomotic leakage, surgical site infection, mortality and length of stay). RESULTS: Six studies (246.383 patients) evaluated MetS and eight studies (9.534 patients) reported on hyperglycemia. Incidence rates of MetS varied widely from 7% to 68% across studies. Meta-analysis showed that patients with MetS are more likely to develop severe complications than those without MetS (RR 1.62, 95% CI 1.01-2.59). Moreover, a non-significant trend toward increased risks for any complication (RR 1.35, 95% CI 0.91-2.00), anastomotic leakage (RR 1.67, 95% CI 0.47-5.93) and mortality (RR 1.19, 95% CI 1.00-1.43) was found. Furthermore, preoperative hyperglycemia was associated with an increased risk of surgical site infection (RR 1.35, 95% CI 1.01-1.81). CONCLUSION: MetS seem to have a negative impact on adverse outcome after colorectal surgery. As a result of few studies meeting inclusion criteria and substantial heterogeneity, evidence is not conclusive. Future prospective observational studies should improve the amount and quality in order to verify current results.

Survival of sentinel node biopsy versus observation in intermediate-thickness melanoma: A Dutch population-based study.

BACKGROUND: The Multicenter Selective Lymphadenectomy Trial (MSLT-1) comparing survival after a sentinel lymph node biopsy (SLNB) versus nodal observation in melanoma patients did not show a significant benefit favoring SLNB. However, in subgroup analyses melanoma-specific survival among patients with nodal metastases seemed better. AIM: To evaluate the association of performing a SLNB with overall survival in intermediate thickness melanoma patients in a Dutch population-based daily clinical setting. METHODS: Survival, excess mortality adjusted for age, gender, Breslow-thickness, ulceration, histological subtype, location, co-morbidity and socioeconomic status were calculated in a population of 1,989 patients diagnosed with malignant cutaneous melanoma (1.2-3.5 mm) on the trunk or limb between 2000-2016 in ten hospitals in the South East area, The Netherlands. RESULTS: A SLNB was performed in 51% of the patients (n = 1008). Ten-year overall survival after SLNB was 75% (95%CI, 71%-78%) compared to 61% (95%CI 57%-64%) following observation. After adjustment for risk factors, a lower risk on death (HR = 0.80, 95%CI 0.66-0.96) was found after SLNB compared to observation only. CONCLUSIONS: SLNB in patients with intermediate-thickness melanoma on trunk or limb resulted in a 14% absolute and significant 10-year survival difference compared to those without SLNB.

Incidence, risk factors, treatment, and survival of ovarian metastases of colorectal origin: a Dutch population-based study.

OBJECTIVE: The aim of this nationwide study was to provide insight in the incidence, risk factors, treatment, and survival of patients with ovarian metastases from colorectal cancer (CRC). METHODS: Data from the Netherlands Cancer Registry were used. All newly diagnosed female CRC patients between 2008 and 2016 were included. Treatment was categorized as follows: cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (CRS-HIPEC); resection of the primary tumor; palliative treatment; and no treatment. Overall survival (OS) was investigated using Kaplan-Meier and multivariable Cox regression analyses. RESULTS: Of 53,883 female CRC patients, 11,343 (21.1%) had metastases at time of diagnosis. Among them, 471 (4.2%) had ovarian metastases. Within latter group, 27.2% received CRS-HIPEC; 38.4% underwent resection of the primary tumor; 25.3% received palliative treatment; and 9.1% received no treatment. Median OS of all patients with ovarian metastases was 17.5 months. In patients receiving CRS-HIPEC, OS was significantly longer than in patients undergoing resection only (median OS 34.1 vs. 17.5 months, adjusted HR 0.44 [0.33-0.66]). Five-year OS was 28.5% for patients having underwent CRS-HIPEC, 11.0% for patients having underwent resection of the primary tumor, 1.2% for patients having underwent palliative treatment, and 0.0% for patients without treatment. CONCLUSIONS: Synchronous ovarian metastases are diagnosed in 4.2% of female colorectal patients presenting with metastatic disease. Risk factors are young age, T4/N+ tumor and histology of signet ring cell carcinoma. Median OS of the entire cohort was 17.5 months, ranging from 3.1 months in patients without treatment to 34.1 months in patients undergoing CRS-HIPEC.

Histological examination of the gallbladder following routine cholecystectomy? A selective analysis is justified.

BACKGROUND: It was hitherto common practice to analyse each removed gallbladder for the presence of gall bladder cancer (GBC) although this approach may be questioned. The aim of this study was to determine whether a policy of selective histopathological analysis (Sel-HPA) is oncologically safe and cost effective. METHODS: This retrospective study was conducted in a single Dutch teaching hospital. Immediately following cholecystectomy, the surgeon decided on the basis of inspection and palpation whether histological examination was indicated. The Dutch Comprehensive Cancer Organisation (IKNL) registry was used to identify the number of GBC during this time period. RESULTS: Of 2271 patients who underwent a cholecystectomy in our institution between January 2012 and December 2017, 1083 (47.7%) were deemed indicated for histopathological analysis. Sixteen pathological gallbladders (1.5%) were identified in that period (intestinal metaplasia, n = 3; low grade dysplasia n = 7; carcinoma n = 6). During follow-up, no patient was found to have GBC recurrence in the population whose gallbladder was not sent for pathology (52.3%, n = 1188, median 49 months of follow up). The percentage of gallbladders that were analysed decreased over the six years of observation from 83% to 38%. Our policy of Sel-HP saved over €65 000. CONCLUSIONS: A policy of selective histopathology after cholecystectomy is oncologically safe and reduces costs.

Selective Histological Examination After Cholecystectomy: An Analysis of Current Daily Practice in The Netherlands.

BACKGROUND: The 2016 Dutch national guidelines on handling of a removed gallbladder for cholelithiasis proposes a selective histopathologic policy (Sel-HP) rather than routine policy (Rout-HP). The aim of this study was to determine the current implementation of the present guideline and the daily practice of Sel-HP. METHODS: Surgeons who were engaged in gallbladder surgery in the Netherlands and were involved in local hospitals' gallbladder protocols completed a questionnaire study regarding gallbladder policy, between December 2017 and May 2018. Data were analyzed using standard statistics. RESULTS: A 100% response rate was obtained (n = 74). Approximately 64% of all gallbladders (n = 22,500) were examined microscopically. Sixty-nine (93.2%) hospitals confirmed they were aware of the new guidelines, and 56 (75.7%) knew the guideline was adjusted in favor of Sel-HP. Half of the hospitals (n = 35, 47.3%) had adopted a Sel-HP, and 39 (52.7%) a Rout-HP. Of the 39 hospitals who had a Rout-HP, 36 were open to a transition to a Sel-HP although some expressed the need for more evidence on safety or novel guidelines. CONCLUSIONS: The current implementation of the 2016 Dutch guideline advising a selective microscopic analysis of removed gallbladders for gallstone disease is suboptimal. Evidence demonstrating safety and cost-effectiveness of an on demand histopathological examination will aid in the implementation process.

Prognostic impact of repeat sentinel lymph node biopsy in patients with ipsilateral breast tumour recurrence.

BACKGROUND: Ipsilateral breast tumour recurrence (IBTR) has an unfavourable prognosis, with a significant subsequent risk of distant recurrence. Repeat sentinel lymph node biopsy (rSLNB) has recently been demonstrated to be technically feasible and useful in tailoring adjuvant treatment plans in patients with IBTR. The prognostic impact of rSLNB in patients with IBTR remains unclear. This study analysed the risk of distant recurrence after IBTR, and evaluated the prognostic impact of rSLNB and other patient and tumour characteristics on distant recurrence-free survival. METHODS: Data were obtained from the SNARB (Sentinel Node and Recurrent Breast Cancer) study. Cox proportional hazards analyses were performed to assess the prognostic effect of tumour, patient and treatment factors on distant recurrence-free survival. RESULTS: Of the 515 included patients, 230 (44·7 per cent) had a tumour-negative rSLNB and 46 (8·9 per cent) a tumour-positive rSLNB. In 239 patients (46·4 per cent) the rSLNB procedure was unsuccessful. After a median follow-up of 5·1 years, 115 patients (22·3 per cent) had developed a recurrence. The overall 5-year distant recurrence-free survival rate was 84·2 (95 per cent c.i. 80·7 to 87·7) per cent. An interval of less than 2 years between primary breast cancer treatment and ipsilateral recurrence (P = 0·018), triple-negative IBTR (P = 0·045) and absence of adjuvant chemotherapy after IBTR (P = 0·010) were independently associated with poor distant recurrence-free survival. The association between the outcome of rSLNB and distant recurrence-free survival was not statistically significant (P = 0·682). CONCLUSION: The outcome of rSLNB is not an important prognostic factor for distant recurrence, and its value as a staging tool in patients with IBTR seems disputable.

Outcome of Surgical Inspection of the Gallbladder in Relation to Final Pathology.

INTRODUCTION: Routine histopathologic gallbladder examination after cholecystectomy has been a point of discussion. The aim of this study was to evaluate the macroscopic examination by the surgeon in relation to the final histology. METHODS: A prospective study was conducted to investigate the practice of macroscopic gallbladder examination by a surgeon compared to routine histopathology by a pathologist. All consecutive cholecystectomies were included between November 2009 and February 2011. RESULTS: A total of 319 consecutive cholecystectomies were performed. Of all macroscopic examinations, the surgeon identified 62 gallbladders with macroscopic abnormalities, ranging from polyps to wall thickening or ulcers. In 55 (17.2%) cases, the surgeon judged that further examination of the specimen by the pathologist could possibly lead to additional and relevant findings. There was a strong agreement between the surgeon and the pathologist concerning the macroscopic examination (κappa = 0.822). The surgeon and the pathologist had disagreement on the macroscopic examination of 18 gallbladders, without clinical consequences for the patient. DISCUSSION: The present prospective study shows that the surgeon should be able to select those gallbladders needing a microscopic gallbladder examination. Potentially, about 80% of this kind of routine histology can be reduced.

Systematic review of exercise training in colorectal cancer patients during treatment.

Colorectal cancer surgery results in considerable postoperative morbidity, mortality and reduced quality of life. As many patients will undergo additional (neo)adjuvant therapy, it is imperative that each individual optimize their physical function. To elucidate the potential of exercise in patient optimization, we investigated the evidence for an exercise program before and after surgical treatment in colorectal cancer patients. A systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions, the guidelines of the Physical Therapy Journal and the PRISMA guidelines. No literature pertaining to exercise training during preoperative neoadjuvant treatment was found. Seven studies, investigating the effects of regular exercise during adjuvant chemotherapy for patients with colorectal cancer or a mixed population, were identified. A small effect (effect size (ES) 0.4) of endurance/interval training and strength training (ES 0.4) was found in two studies conducted in patients with colorectal and gastrointestinal cancer. In five studies that included a mixed population of cancer patients, interval training resulted in a large improvement (ES 1.5; P≤.05). Endurance training alone was found to increase both lower extremity strength and endurance capacity. The effects of strength training in the lower extremity are moderate, whereas, in the upper extremity, the increase is small. There is limited evidence available on exercise training during treatment in colorectal cancer patients. One study concluded exercise therapy may be beneficial for colorectal cancer patients during adjuvant treatment. The possible advantages of training during neoadjuvant treatment may be explored by prehabilitation trials.

Non-visualized sentinel nodes in breast cancer patients; prevalence, risk factors, and prognosis.

BACKGROUND: Evidence and consensus is lacking in international guidelines regarding axillary treatment recommendations for patients in whom a sentinel lymph node (SLN) cannot be visualized (non-vSLN) during the sentinel node procedure. In this study we aimed to determine the prevalence of non-vSLNs in a Dutch population of breast cancer patients and to examine predictors and survival rate for non-vSLN. METHODS: A nationwide, retrospective, population-based study was performed including 116,920 patients with invasive breast cancer who underwent a SLN procedure in the Netherlands between January 2005 and December 2013. RESULTS: Of the 76,472 clinically negative patients who underwent a SLN procedure, 1924 patients (2.5%) had a non-vSLN, of whom 1552 (80.7%) underwent an ALND. Multivariate analysis showed predictive factors for non-vSLN: older age (p < 0.001), diagnosis in the period 2005-2009 (p < 0.001), larger tumor size (p = 0.003), and extensive nodal involvement (p < 0.001). Multivariate survival analysis showed a significantly worse survival (HR 1.18, 95% CI 1.03-1.34, p = 0.015) for non-vSLNs patients. However, in the non-vSLN group, an ALND was not statistically significantly associated with a better survival (HR 0.96, 95% CI 0.53-1.75, p = 0.891). CONCLUSION: Patients with non-vSLNs had less favorable disease characteristics and a worse survival compared to patients with a visualized SLN. Performing an ALND was not associated with a significantly better survival in patients with non-vSLNs. However, further research on the necessity of axillary treatment in this specific patient group is required.