Stage-Specific Risk of Recurrence and Death From Melanoma in Denmark, 2008-2021: A National Observational Cohort Study of 25 720 Patients With Stage IA to IV Melanoma.

Importance: To ensure optimal treatment and surveillance of patients with melanoma, knowledge of the clinical stage-specific risk of recurrence, mortality, and recurrence patterns across the American Joint Committee on Cancer Eighth Edition (AJCC8) substages is needed. Objective: To estimate stage-specific recurrence and melanoma-specific mortality rates, assess absolute stage-specific risks of recurrence and mortality, and describe stage-specific recurrence patterns, including conditional rates. Design: Retrospective cohort study of prospectively collected nationwide population-based registry data. Setting: Nationwide, population-based cohort study. Participants: The 25 720 Danish patients, 18 years or older, diagnosed with first-time stage IA to IV cutaneous melanoma between January 1, 2008, and December 31, 2019, were included and followed up from time of primary treatment until December 31, 2021. Exposures: First diagnosis of stage IA to IV cutaneous melanoma. Main Outcomes: Stage-specific cumulative incidence of recurrence and melanoma-specific mortality, melanoma-specific recurrence-free survival, and assessed absolute stage-specific risks of recurrence and melanoma-specific mortality. Secondary outcomes were stage-specific recurrence patterns, including conditional rates, and melanoma-specific survival. Results: We followed up 25 720 patients for a median of 5.9 years (95% CI, 58.9-59.3 years). Mean age was 59.1 years (95% CI, 58.9-59.3 years). Patients with stage IIB to IIC melanoma were older, had more comorbidities at diagnosis, and had the lowest rate of pathologic staging by sentinel node biopsy (81.6%-87.4%). A total of 10.6% of patients developed recurrence; first recurrence included distant recurrence, alone or with synchronous locoregional recurrence, in 56.6% of patients. We found a comparable risk of recurrence in stages IIIA and IIB (29.7% vs 33.2%) and in stages IIIB and IIC (35.9% vs 36.8%), respectively. Melanoma-specific mortality was comparable between stages IIIA and IIA (13.0% vs 13.6%) and between stages IIIB and IIB (18.4% vs 22.0%), respectively. These risk patterns persisted in cause-specific hazards models. Conclusions and Relevance: This nationwide, population-based cohort study found that the increasing stages of the current AJCC8 staging system do not accurately reflect an increasing risk of recurrence and mortality in melanoma. The high proportion of distant recurrences suggests that hematogenous spread is a more common metastatic pathway than previously assumed, and surveillance with routine functional/cross-sectional imaging should be considered for stages IIB to IV. Future efforts should be put toward developing new tools for risk stratification and determining the survival effect of routine imaging in surveillance.

Prognostic Significance and Management of Sentinel Nodes in the Triangular Intermuscular Space of Patients with Melanoma.

BACKGROUND: The clinical significance of sentinel nodes (SNs) in the triangular intermuscular space (TIS) of patients with melanoma is poorly understood. This study aimed to determine their incidence and positivity rate, and to report their management and patient outcomes. METHODS: This was a single-institution retrospective cohort study of patients with unilateral or bilateral TIS SNs on lymphoscintigraphy treated between 1992 and 2017. Recurrence-free survival was analyzed. RESULTS: Lymphoscintigraphy identified TIS SNs in 266 patients. They were bilateral in 17 patients. Of the 2296 patients with a melanoma on the upper back, 259 (11%) had TIS SNs. Procurement of SNs was not attempted in 122 (43%) of the 283 cases and failed in 11 cases (7%). An SN was successfully retrieved from the TIS in 145 patients (53%) and contained metastasis in 18 of 150 TIS SNs. This was the only positive SN in 12 patients (8%), upstaging all of them. Of the 18 patients with a positive SN in the TIS, 9 (50%) underwent completion axillary lymph node dissection, but no additional involved nodes were found in any of these patients. Recurrence in the TIS was observed in six patients (5%), none of whom had their TIS SN surgically pursued previously. CONCLUSIONS: Lymphoscintigraphy showed TIS SNs in 11% of patients with melanomas on their upper back. In such cases, retrieval of TIS SNs is required for accurate staging and to minimize the risk of TIS recurrence.

Thin or early melanoma, risk factors and associated mortality.

INTRODUCTION: The incidence of thin and early-stage melanoma is increasing in many populations, but the clinical significance of these lesions remains partly unknown. METHODS: Firstly, melanoma deaths in Denmark (2009-2018) were followed back to establish melanoma debut in these persons. Secondly, using national registries of cancer incidence and mortality, 27,036 persons with thin or early-stage melanoma were followed-up for melanoma death. RESULTS: It is estimated that in 11% of the persons who died from melanoma, the debut was a thin or early-stage melanoma. On follow-up of persons with thin or early-stage melanoma, the 20-year risk of dying from melanoma was 3%. CONCLUSION: The absolute risk of melanoma death after a diagnosis with thin or early-stage melanoma is low. A subgroup of patients who are at a high risk may possibly be identified by a combination of stage, thickness, ulceration and dermal mitoses. FUNDING: none. TRIAL REGISTRATION: not relevant.

Fine needle and core needle ultrasound guided biopsies for assessing suspected melanoma metastasis in lymph nodes and subcutaneous tissue.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the diagnostic accuracy of ultrasound guided fine needle aspiration cytology (FNAC) and core needle biopsy (CNB) in different clinical scenarios for melanoma patients with lesions suspected of metastasis. METHODS: We included all patients at our department attending follow-up after surgery for cutaneous melanoma, who had undergone either FNAC or CNB between December 2016 and June 2019. Biopsy results were classified into one of four categories and verified with follow-up including imaging, re-biopsy or histology upon excision. The diagnostic accuracy of FNAC and CNB were calculated overall, and based on location of suspected metastasis, reason for suspicion and stage. RESULTS: We identified 232 biopsies in 164 patients; 109 FNACs and 123 CNBs. For FNAC, overall sensitivity was 83.3% and negative predictive value was 88.4%. For CNB, overall sensitivity was 92.4% and negative predictive value was 88.0%. There were significantly fewer nondiagnostic results using CNB compared to FNAC (χ1 2 = 6.7, p = 0.0095). CONCLUSIONS: There were no significant differences between the diagnostic accuracy of FNAC and CNB in the different clinical scenarios. We found significantly fewer nondiagnostic biopsies when using CNB, although this may reflect the type of lesions selected for each approach.

More sentinel lymph node biopsies for thin melanomas after transition to AJCC 8th edition do not increase positivity rate: A Danish population-based study of 7148 patients.

BACKGROUND: We evaluated the outcome of sentinel lymph node biopsies (SLNB) in patients with thin melanoma before and after the implementation of AJCC 8th edition (AJCC8) and identified predictors of positive sentinel lymph nodes (+SLN). METHODS: Patients diagnosed with T1 melanomas (Breslow thickness ≤1 mm) during 2016-2017 as per AJCC 7th edition (AJCC7) (n = 3414) and 2018-2019 as per AJCC8 (n = 3734) were identified in the Danish Melanoma Database. RESULTS: More SLNBs were performed in the AJCC8 cohort compared to the AJCC7 (22.2% vs. 16.2%, p < 0.001), with no significant difference in +SLN rates (4.7% vs. 6.7%, p = 0.118). In the AJCC7 + SLN subgroup, no melanomas were ulcerated, 94.6% had mitotic rate (MR) ≥ 1, 67.6% were ≥0.8 mm and 32.4% would be T1a according to AJCC8. In the AJCC8 + SLN subgroup, 10.3% were ulcerated, 74.4% had MR≥ 1, 97.4% were ≥0.8 mm and 23.1% would be T1a according to AJCC7. On multivariable analysis younger age and MR ≥ 1 were significant predictors of +SLN. CONCLUSION: More SLNBs were performed in T1 melanomas after transition to AJCC8 without an increase in +SLN rate. None of the AJCC8 T1b criteria were significant predictors of +SLN. We suggest that mitosis and younger age should be considered as indications for SLNB in thin melanoma.

Association Between Melanoma Detected During Routine Skin Checks and Mortality.

IMPORTANCE: Early melanoma diagnosis is associated with better health outcomes, but there is insufficient evidence that screening, such as having routine skin checks, reduces mortality. OBJECTIVE: To assess melanoma-specific and all-cause mortality associated with melanomas detected through routine skin checks, incidentally or patient detected. A secondary aim was to examine patient, sociodemographic, and clinicopathologic factors associated with different modes of melanoma detection. DESIGN, SETTING, AND PARTICIPANTS: This prospective, population-based, cohort study included patients in New South Wales, Australia, who were diagnosed with melanoma over 1 year from October 23, 2006, to October 22, 2007, in the Melanoma Patterns of Care Study and followed up until 2018 (mean [SD] length of follow-up, 11.9 [0.3] years) by using linked mortality and cancer registry data. All patients who had invasive melanomas recorded at the cancer registry were eligible for the study, but the number of in situ melanomas was capped. The treating doctors recorded details of melanoma detection and patient and clinical characteristics in a baseline questionnaire. Histopathologic variables were obtained from pathology reports. Of 3932 recorded melanomas, data were available and analyzed for 2452 (62%; 1 per patient) with primary in situ (n = 291) or invasive (n = 2161) cutaneous melanoma. Data were analyzed from March 2020 to January 2021. MAIN OUTCOMES AND MEASURES: Melanoma-specific mortality and all-cause mortality. RESULTS: A total of 2452 patients were included in the analyses. The median age at diagnosis was 65 years (range, 16-98 years), and 1502 patients (61%) were men. A total of 858 patients (35%) had their melanoma detected during a routine skin check, 1148 (47%) self-detected their melanoma, 293 (12%) had their melanoma discovered incidentally when checking another skin lesion, and 153 (6%) reported "other" presentation. Routine skin-check detection of invasive melanomas was associated with 59% lower melanoma-specific mortality (subhazard ratio, 0.41; 95% CI, 0.28-0.60; P < .001) and 36% lower all-cause mortality (hazard ratio, 0.64; 95% CI, 0.54-0.76; P < .001), adjusted for age and sex, compared with patient-detected melanomas. After adjusting for prognostic factors including ulceration and mitotic rate, the associations were 0.68 (95% CI, 0.44-1.03; P = .13), and 0.75 (95% CI, 0.63-0.90; P = .006), respectively. Factors associated with higher odds of routine skin-check melanoma detection included being male (female vs male, odds ratio [OR], 0.73; 95% CI, 0.60-0.89; P = .003), having previous melanoma (vs none, OR, 2.36; 95% CI, 1.77-3.15; P < .001), having many moles (vs not, OR, 1.39; 95% CI, 1.10-1.77; P = .02), being 50 years or older (eg, 50-59 years vs <40 years, OR, 2.89; 95% CI, 1.92-4.34; P < .001), and living in nonremote areas (eg, remote or very remote vs major cities, OR, 0.23; 95% CI, 0.05-1.04; P = .003). CONCLUSIONS AND RELEVANCE: In this cohort study, melanomas diagnosed through routine skin checks were associated with significantly lower all-cause mortality, but not melanoma-specific mortality, after adjustment for patient, sociodemographic, and clinicopathologic factors.

[Merkel cell carcinoma].

Merkel cell carcinoma is a neuroendocrine skin carcinoma caused by the Merkel cell virus and ultraviolet radiation. Approximately 25 Danish patients are diagnosed each year. Merkel cell carcinoma is often located on the sun-exposed areas of the skin and definitive diagnosis is made by the pathologist. Patients are treated at the department of plastic surgery and oncology with treatment modalities including surgery, radiotherapy, immunotherapy and chemotherapy as summarised in this review.

The worse survival outcomes reported for melanoma patients having sentinel node biopsy after lymphoscintigraphy the previous day do not appear to be due to overnight migration of Tc99m-nanocolloid tracer.

INTRODUCTION: It has been reported that the survival of patients having sentinel node (SN) biopsy for melanoma the day after lymphoscintigraphy using Tc99m-nanocolloid is worse than that of patients having lymphoscintigraphy and SN biopsy on the same day [1,2]. A possible explanation suggested is that overnight migration of the tracer from SNs to 2nd-tier nodes occurs, causing failure to remove true SNs. MATERIALS AND METHODS: The possibility of overnight tracer migration leading to errors in SN-identification was investigated in 12 patients scheduled for lymphoscintigraphy the day before surgery by repeating SPECT-CT imaging the next morning, before their SN biopsy. The aim was to check whether onward migration of colloid from previously-identified SNs had occurred. RESULTS: No significant migration of Tc99m-nanocolloid occurred overnight in any patient. All nodes reported to be SNs on day 1 imaging were also present and regarded as SNs on day 2 images. No new foci were visualised on day 2, but some that had been identified on day 1 were not seen on day 2. CONCLUSIONS: Since migration of nanocolloid overnight did not occur, this cannot explain the reported survival disadvantage for patients undergoing SN biopsy the day after lymphoscintigraphy. A likely alternative possibility is that inadequate doses of radioisotope were used for next-day procedures, causing the mistaken removal of 2nd-tier nodes instead of true SNs more frequently. Further research is required to explain the reported reduction in survival of patients having next-day SN biopsy procedures, since the possibility has important clinical implications.

Staging 18F-FDG PET/CT influences the treatment plan in melanoma patients with satellite or in-transit metastases.

Whole-body positron emission tomography/computed tomography (PET/CT) and brain magnetic resonance imaging (MRI) are commonly used to stage patients with palpable lymph node metastases from melanoma, but their role in patients with satellite and/or in-transit metastasis (S&ITM) is unclear. The aim of this study was to establish the diagnostic value of PET/CT and brain MRI in these patients, and to assess their influence on subsequent management decisions. In this prospective study, 25 melanoma patients with a first presentation of S&ITM who had no clinical evidence of palpable nodal or distant metastasis underwent whole-body F-FDG PET/CT and brain MRI after a tentative pre-scan treatment plan had been made. Sensitivity and specificity of imaging were determined by pathological confirmation, clinical outcome and repeat PET/CT and MRI at 6 months. PET/CT led to a modification of the initial treatment plan in four patients (16%). All four were upstaged (AJCC stage eighth edition). PET/CT was false-positive in one patient, who had a Schwannoma in his trapezius muscle. A thyroid carcinoma was an incidental finding in another patient. The sensitivity of PET/CT was 58% and specificity 83%. In 6 months following the baseline PET/CT, further sites of in-transit or systemic disease were identified in 10 patients (40%). Brain MRI did not alter the treatment plan or change the disease stage in any patient. Whole-body PET/CT improved staging in melanoma patients with S&ITM and changed the originally-contemplated treatment plan in 16%. MRI of the brain appeared not to be useful.

Management Recommendations for Merkel Cell Carcinoma-A Danish Perspective.

Merkel cell carcinoma (MCC) is a rare malignant neuroendocrine carcinoma of the skin with a poor prognosis and an apparent increase in incidence. Due to its rarity, evidence-based guidelines are limited, and there is a lack of awareness among clinicians. This review constitutes the consensus management recommendations developed by the Danish MCC expert group and is based on a systematic literature search. Patients with localized disease are recommended surgical excision and adjuvant radiotherapy to the primary site; however, this may be omitted in patients with MCC with low risk features. Patients with regional lymph node involvement are recommended complete lymph node removal and adjuvant radiotherapy in case of extracapsular disease. Metastatic disease was traditionally treated with chemotherapy, however, recent clinical trials with immune therapy have been promising. Immune checkpoint inhibitors targeting the programmed cell death protein 1(PD-1)/programmed death-ligand 1(PD-L1) axis should therefore be strongly considered as first-line treatment for fit patients. A 5-year follow-up period is recommended involving clinical exam every 3 months for 2 years and every 6 months for the following 3 years and PET-CT one to two times a year or if clinically indicated. These national recommendations are intended to offer uniform patient treatment and hopefully improve prognosis.

Measured and genetically predicted plasma YKL-40 levels and melanoma mortality.

PURPOSE: High plasma levels of YKL-40 might be associated with mortality in patients with melanoma, and it is unknown if YKL-40 is causally related to mortality. EXPERIMENTAL DESIGN: We studied two cohorts: 2618 patients with melanoma from hospital clinics and 1413 general population patients with melanoma, totalling 4031 patients followed up for mortality end-points for up to 20 years. All were genotyped for CHI3L1 rs4950928, highly predictive of lifelong plasma YKL-40, and plasma YKL-40 levels were measured in 2165 patients. We tested the hypotheses that measured and genetically predicted high plasma YKL-40 are associated with increased mortality in patients with melanoma. RESULTS: For the hospital melanoma cohort, age- and sex-adjusted hazard ratios for death in individuals with measured plasma YKL-40 in the 96-100th percentile versus 1-95th percentile and per 10-percentile increase were 1.52 (95% confidence interval, 1.07-2.16) and 1.07 (1.02-1.11), respectively, most pronounced for patients with localised melanomas. Each C-allele of the CHI3L1 rs4950928 genotype was associated with plasma YKL-40 level increases of 32% in the hospital melanoma cohort (p = 6 × 10-48) and 43% in the general population melanoma cohort (p = 7 × 10-13). Multifactorially adjusted ratios for these increases in the combined cohorts were 1.04 (1.00-1.09) observationally for measured plasma YKL-40 and 0.98 (0.86-1.12) for the genetically predicted plasma YKL-40. CONCLUSION: Measured, but not genetically predicted, increasing plasma YKL-40 was associated with increased mortality in patients with melanoma. Plasma YKL-40 is a marker but less likely to be a cause of increased mortality in patients with melanoma.

Subungual Melanoma of the Hand.

BACKGROUND: The diagnosis of subungual melanoma (SUM) can be challenging and SUMs generally have a worse prognosis than melanomas arising elsewhere. Due to their rarity, the evidence to guide management is limited. This study sought to identify clinicopathological features predictive of outcome and to provide guidelines for management. METHODS: From a large, single-institution database, 103 patients with in situ (n = 9) or invasive (n = 94) SUMs of the hand treated between 1953 and 2014 were identified and their features analyzed. RESULTS: The most common site of hand SUMs was the thumb (53%). Median tumor thickness was 3.1 mm, and SUMs were commonly of the acral subtype (57%), ulcerated (58%), amelanotic (32%), and had mitoses (73%). Twenty-one patients reported prior trauma to the tumor site. Twenty-two patients were stage III at diagnosis; 7 underwent therapeutic lymph node dissection and 22 underwent elective lymph node dissection (5 positive), while 36 had sentinel node biopsy (SNB), 28% of which were positive. Forty percent of SNB-positive patients had involved non-sentinel nodes (SNs) in their completion lymph node dissection. Five-year melanoma-specific survival (MSS) and disease-free survival (DFS) rates were 70% and 52%, respectively. On multivariate analysis, regional node metastasis and right-hand tumor location were significant predictors of shorter DFS and MSS, whereas mitoses negatively impacted DFS only and increasing Breslow thickness impacted MSS only. CONCLUSIONS: This study confirms that SUMs on the hand usually present at an advanced stage. Distal amputation appears safe for invasive SUMs, and SNB should be considered as these patients have a high risk of both SN and non-SN metastasis.

Targeted ultrasound and fine-needle aspiration cytology for sentinel node diagnostics in early-stage melanoma: a validation study.

Ultrasound-guided fine-needle aspiration cytology (US-FNAC) is used to evaluate the involvement of lymph nodes in various malignant diseases. Its value in detecting sentinel lymph node (SN) metastasis preoperatively in melanoma patients is controversial and is the subject of this study. In this prospective validation study, 91 consecutive patients with melanoma clinical stage I (n=64) and II (n=27) were examined with US-FNAC before SN biopsy from 2012 to 2014 at a tertiary center. All patients underwent lymphoscintigraphy before the US-FNAC. Lymph nodes that showed any of the Berlin morphologic criteria on ultrasonography were examined using FNAC. The median Breslow thickness of the melanomas was 1.22 mm (range: 0.47-11.5 mm). Twenty-two percent of the patients had metastases in their SNs, 90% of which were smaller than 2 mm in largest diameter. The percentages of metastases with a size more than 1 mm were 50 and 29%, respectively, in the true-positive and false-negative US groups. The sensitivity, specificity, positive predictive value, and negative predictive value for overall US examination were 30, 81, 24, and 83%, respectively. None of the FNACs contained conclusive malignant cells. The specificity of the FNAC was 76%. Our results show that US-FNAC was not a useful diagnostic tool in our setting as it did not add significantly to the staging and management of patients with mainly thin cutaneous melanomas, perhaps because of the often small size of the SN metastases. It may be useful in the early diagnosis of lymph node metastases in a subgroup of melanoma patients with larger metastases.

EANM practice guidelines for lymphoscintigraphy and sentinel lymph node biopsy in melanoma.

PURPOSE: Sentinel lymph node biopsy is an essential staging tool in patients with clinically localized melanoma. The harvesting of a sentinel lymph node entails a sequence of procedures with participation of specialists in nuclear medicine, radiology, surgery and pathology. The aim of this document is to provide guidelines for nuclear medicine physicians performing lymphoscintigraphy for sentinel lymph node detection in patients with melanoma. METHODS: These practice guidelines were written and have been approved by the European Association of Nuclear Medicine (EANM) to promote high-quality lymphoscintigraphy. The final result has been discussed by distinguished experts from the EANM Oncology Committee, national nuclear medicine societies, the European Society of Surgical Oncology (ESSO) and the European Association for Research and Treatment of Cancer (EORTC) melanoma group. The document has been endorsed by the Society of Nuclear Medicine and Molecular Imaging (SNMMI). CONCLUSION: The present practice guidelines will help nuclear medicine practitioners play their essential role in providing high-quality lymphatic mapping for the care of melanoma patients.

Diverse presentations of acral melanoma.

BACKGROUND: Acral melanoma (AM) is an uncommon melanoma subtype occurring on the palms, soles and nail apparatus. It often lacks the typical features of primary melanoma resulting in delayed diagnosis. OBJECTIVE: This article aims to raise awareness of AM and promote a high index of clinical suspicion to enable early diagnosis and improve outcomes for patients with AM. DISCUSSION: The diagnosis of AM is often delayed because its presentation mimics other benign conditions such as fungal infections and ulcers. When lesions that were thought to be benign fail to respond to appropriate therapies, biopsy is critically important to exclude AM or other malignant pathology. Clinician awareness of the diversity of AM presentations, maintaining AM as part of their differential diagnosis and facilitating early biopsy are essential for early diagnosis and improving outcomes in patients with AM.

The diagnostic value of adding dynamic scintigraphy to standard delayed planar imaging for sentinel node identification in melanoma patients.

PURPOSE: The aim of this study was to compare early dynamic imaging combined with delayed static imaging and single photon emission computed tomography (SPECT)/CT with delayed, planar, static imaging alone for sentinel node (SN) identification in melanoma patients. METHODS: Three hundred and seven consecutive melanoma patients referred for SN biopsy (SNB) were examined using combined imaging. Secondary interpretation of only the delayed static images was subsequently performed. In 220 patients (72%), complete surgical and pathological information relating to the SNB was available. The number of SNs identified and number of patients with positive SNs were compared between the two interpretations of the imaging studies and, when available, related to pathology data. RESULTS: A slightly higher number of SNs (mean 0.12/patient) was identified when interpreting only delayed static images compared to combined imaging. In a direct patient-to-patient comparison, the number of SN(s) identified on the combined vs static images only showed moderate agreement (kappa value 0.56). In 38 patients (17%), positive SNs were identified by the combined procedure compared to 35 (16%) by static imaging only. Thus by static imaging only, tumour-positive SNs were not identified in 3 of 38 patients (8%). CONCLUSION: For SN identification in melanoma patients, dynamic imaging combined with delayed static imaging and SPECT/CT is superior to delayed static imaging only because the latter is more likely to fail to identify SNs containing metastases.

Axillary sentinel node identification in breast cancer patients: degree of radioactivity present at biopsy is critical.

BACKGROUND: The radioactivity present in the patient (Act(rem) ) at sentinel node (SN) biopsy will depend on injected activity amount as well as on the time interval from tracer injection to biopsy, which both show great variations in the literature. The purpose of this study was to analyse the influence of varying Act(rem) levels on the outcome of axillary SN biopsy in patients with breast cancer (BC). MATERIAL AND METHODS: Eight hundred and fifty-eight patients with BC were consecutively referred to SN biopsy, 21% for a same-day and 79% of the patients for a 2-day procedure. Four hundred and nineteen patients underwent scintigraphy and 439 did not. For same-day procedures, 50 MBq (99m) Tc-nanocolloid (Nanocoll(®) ) was injected, and for 2-day procedures 110 MBq. For the analysis of SN biopsy outcome, the patients were divided into three Act(rem) groups: <10 (56% of the patients), 10-20 (23%), and >20 MBq (21%). During surgery, SNs were located using a hand-held gamma probe supported by image information when available and blue dye injection. Pathology included haematoxylin-eosin staining followed by immunohistochemistry. RESULTS: The number of SNs removed (mean value 1·87 versus 2·14, P = 0·0003) and the probability of finding a malignant SN (P = 0·034) were lower in the <10 MBq group of patients compared with higher Act(rem) >20 MBq. Of the 25 patients with SN non-detection, 20 patients had an Act(rem) <10 MBq. Imaging had no significant influence on the number of patients with a malignant SN (P = 0·48). CONCLUSION: Act(rem) above 10 MBq for nanocolloid tracer appears important for appropriate identification of SNs in patients with BC.