ABSTRACT
BACKGROUND: The 31-gene expression profile test (Class 1A: low-risk; 1B/2A: intermediate-risk; 2B: high-risk) is validated to identify patients with cutaneous melanoma who can safely forego sentinel lymph node biopsy (SLNB). The objective of the current study is to quantify SLNB reduction by clinicians using 31-GEP. METHODS: Patients with T1-T2 tumors eligible for SLNB were seen by surgical oncologists (89.1%), dermatologists (7.8%), and medical oncologists (3.1%). After receiving 31-GEP results but before SLNB, clinicians were asked which clinical and pathological features influenced SLNB decisions (n = 191). The Exact binomial test was used to compare SLNB procedure rates to a contemporary study (78% SLNB baseline rate). Logistic regression modeling (odds ratio [OR], 95% CI) was used to identify features associated with SLNB procedure rates. RESULTS: One hundred clinical decisions (52.4%) were influenced by the 31-GEP to forego SLNB and 70% (70/100) were not performed. Of the 30 performed, 0% (0/30) were positive. The 31-GEP influenced sixty-three clinical decisions (33.0%) to perform SLNB, and 92.1% (58/63) were performed. There was a clinically meaningful 29.4% reduction of SLNBs performed in patients with a Class 1A result relative to the baseline rate of 78.0% (p < .01). In patients ≥55 or ≥65-year-old, SLNB reduction was 32.3% (p < .01), 28.3% (p < .01), respectively. Overall, 85.3% of decisions relating to SLNB were influenced by 31-GEP results. CONCLUSION: In this prospective, multicenter study, clinicians demonstrated clinically meaningful use of the 31-GEP test to forego or pursue SLNB in patients with T1-T2 tumors resulting in a significant, risk appropriate decrease in SLNBs.
Subject(s)
Melanoma , Skin Neoplasms , Humans , Aged , Melanoma/genetics , Melanoma/surgery , Melanoma/pathology , Skin Neoplasms/genetics , Skin Neoplasms/surgery , Skin Neoplasms/pathology , Sentinel Lymph Node Biopsy , Transcriptome , Prospective Studies , Prognosis , Melanoma, Cutaneous MalignantSubject(s)
Melanoma , Sentinel Lymph Node , Skin Neoplasms , Denmark/epidemiology , Humans , Melanoma/pathology , Melanoma/surgery , Neoplasm Staging , Prognosis , Retrospective Studies , Sentinel Lymph Node/pathology , Sentinel Lymph Node/surgery , Sentinel Lymph Node Biopsy , Skin Neoplasms/pathology , Skin Neoplasms/surgeryABSTRACT
National guidelines recommend sentinel lymph node biopsy (SLNB) be offered to patients with > 10% likelihood of sentinel lymph node (SLN) positivity. On the other hand, guidelines do not recommend SLNB for patients with T1a tumors without high-risk features who have < 5% likelihood of a positive SLN. However, the decision to perform SLNB is less certain for patients with higher-risk T1 melanomas in which a positive node is expected 5%-10% of the time. We hypothesized that integrating clinicopathologic features with the 31-gene expression profile (31-GEP) score using advanced artificial intelligence techniques would provide more precise SLN risk prediction. METHODS: An integrated 31-GEP (i31-GEP) neural network algorithm incorporating clinicopathologic features with the continuous 31-GEP score was developed using a previously reported patient cohort (n = 1,398) and validated using an independent cohort (n = 1,674). RESULTS: Compared with other covariates in the i31-GEP, the continuous 31-GEP score had the largest likelihood ratio (G2 = 91.3, P < .001) for predicting SLN positivity. The i31-GEP demonstrated high concordance between predicted and observed SLN positivity rates (linear regression slope = 0.999). The i31-GEP increased the percentage of patients with T1-T4 tumors predicted to have < 5% SLN-positive likelihood from 8.5% to 27.7% with a negative predictive value of 98%. Importantly, for patients with T1 tumors originally classified with a likelihood of SLN positivity of 5%-10%, the i31-GEP reclassified 63% of cases as having < 5% or > 10% likelihood of positive SLN, for a more precise, personalized, and clinically actionable SLN-positive likelihood estimate. CONCLUSION: These data suggest the i31-GEP could reduce the number of SLNBs performed by identifying patients with likelihood under the 5% threshold for performance of SLNB and improve the yield of positive SLNBs by identifying patients more likely to have a positive SLNB.
Subject(s)
Gene Expression Profiling/standards , Melanoma/diagnosis , Gene Expression Profiling/methods , Gene Expression Profiling/statistics & numerical data , Humans , Lymphatic Metastasis/diagnosis , Lymphatic Metastasis/prevention & control , Melanoma/surgery , Sentinel Lymph Node/pathology , Sentinel Lymph Node/physiopathology , Sentinel Lymph Node Biopsy/methods , Sentinel Lymph Node Biopsy/standards , Sentinel Lymph Node Biopsy/statistics & numerical dataABSTRACT
Gene expression profile (GEP) testing is now commercially available for metastatic risk prediction in patients with cutaneous squamous cell carcinoma (CSCC) and one or more high-risk factors. The purpose of this article is to provide an early framework for healthcare providers looking to integrate patient-specific tumor biology into their clinical practice using GEP testing. To develop a framework for clinical use, an expert panel was convened to identify CSCC management decision points where GEP testing may be immediately incorporated into practice until the definitive results of prospective trials become available. Based on their discussion, the expert panel focused on the areas of nodal evaluation, adjuvant radiation therapy, and follow-up and surveillance. The panel emphasized that GEP prognostic test results should not currently be used as a surrogate for standard of care treatment but as an additional data point when determining individualized management for patients with high-risk CSCC. Whenever possible, decisions on management plans for these patients should be developed with multidisciplinary input. J Drugs Dermatol. 2021;20:6(Suppl):s5-11. doi:10.36849/JDD.6068.
Subject(s)
Carcinoma, Squamous Cell , Skin Neoplasms , Carcinoma, Squamous Cell/diagnosis , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/therapy , Gene Expression Profiling , Humans , Neoplasm Staging , Prospective Studies , Skin Neoplasms/diagnosis , Skin Neoplasms/genetics , Skin Neoplasms/therapyABSTRACT
Purpose To determine the pathologic complete response (pCR) rate in estrogen receptor (ER) -positive primary breast cancer triaged to chemotherapy when the protein encoded by the MKI67 gene (Ki67) level was > 10% after 2 to 4 weeks of neoadjuvant aromatase inhibitor (AI) therapy. A second objective was to examine risk of relapse using the Ki67-based Preoperative Endocrine Prognostic Index (PEPI). Methods The American College of Surgeons Oncology Group (ACOSOG) Z1031A trial enrolled postmenopausal women with stage II or III ER-positive (Allred score, 6 to 8) breast cancer whose treatment was randomly assigned to neoadjuvant AI therapy with anastrozole, exemestane, or letrozole. For the trial ACOSOG Z1031B, the protocol was amended to include a tumor Ki67 determination after 2 to 4 weeks of AI. If the Ki67 was > 10%, patients were switched to neoadjuvant chemotherapy. A pCR rate of > 20% was the predefined efficacy threshold. In patients who completed neoadjuvant AI, stratified Cox modeling was used to assess whether time to recurrence differed by PEPI = 0 score (T1 or T2, N0, Ki67 < 2.7%, ER Allred > 2) versus PEPI > 0 disease. Results Only two of the 35 patients in ACOSOG Z1031B who were switched to neoadjuvant chemotherapy experienced a pCR (5.7%; 95% CI, 0.7% to 19.1%). After 5.5 years of median follow-up, four (3.7%) of the 109 patients with a PEPI = 0 score relapsed versus 49 (14.4%) of 341 of patients with PEPI > 0 (recurrence hazard ratio [PEPI = 0 v PEPI > 0], 0.27; P = .014; 95% CI, 0.092 to 0.764). Conclusion Chemotherapy efficacy was lower than expected in ER-positive tumors exhibiting AI-resistant proliferation. The optimal therapy for these patients should be further investigated. For patients with PEPI = 0 disease, the relapse risk over 5 years was only 3.6% without chemotherapy, supporting the study of adjuvant endocrine monotherapy in this group. These Ki67 and PEPI triage approaches are being definitively studied in the ALTERNATE trial (Alternate Approaches for Clinical Stage II or III Estrogen Receptor Positive Breast Cancer Neoadjuvant Treatment in Postmenopausal Women: A Phase III Study; clinical trial information: NCT01953588).
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Aromatase Inhibitors/therapeutic use , Breast Neoplasms/chemistry , Breast Neoplasms/drug therapy , Ki-67 Antigen/analysis , Neoplasm Recurrence, Local , Aged , Anastrozole , Androstadienes/therapeutic use , Breast Neoplasms/pathology , Breast Neoplasms/surgery , Clinical Decision-Making , Female , Follow-Up Studies , Humans , Ki-67 Antigen/genetics , Letrozole , Middle Aged , Mitotic Index , Neoadjuvant Therapy/methods , Neoplasm Metastasis , Neoplasm Staging , Nitriles/therapeutic use , Predictive Value of Tests , Prognosis , Proportional Hazards Models , Receptors, Estrogen/analysis , Receptors, Estrogen/genetics , Receptors, Progesterone/genetics , Survival Rate , Transcriptome , Triazoles/therapeutic useABSTRACT
OBJECTIVE: The aim of this study was to determine the impact of the results of the 12-gene DCIS Score assay on (i) radiotherapy recommendations for patients with pure ductal carcinoma in situ (DCIS) following breast-conserving surgery (BCS), and (ii) patient decisional conflict and state anxiety. METHODS: Thirteen sites across the US enrolled patients (March 2014-August 2015) with pure DCIS undergoing BCS. Prospectively collected data included clinicopathologic factors, physician estimates of local recurrence risk, DCIS Score results, and pre-/post-assay radiotherapy recommendations for each patient made by a surgeon and a radiation oncologist. Patients completed pre-/post-assay decisional conflict scale and state-trait anxiety inventory instruments. RESULTS: The analysis cohort included 127 patients: median age 60 years, 80 % postmenopausal, median size 8 mm (39 % ≤5 mm), 70 % grade 1/2, 88 % estrogen receptor-positive, 75 % progesterone receptor-positive, 54 % with comedo necrosis, and 18 % multifocal. Sixty-six percent of patients had low DCIS Score results, 20 % had intermediate DCIS Score results, and 14 % had high DCIS Score results; the median result was 21 (range 0-84). Pre-assay, surgeons and radiation oncologists recommended radiotherapy for 70.9 and 72.4 % of patients, respectively. Post-assay, 26.4 % of overall recommendations changed, including 30.7 and 22.0 % of recommendations by surgeons and radiation oncologists, respectively. Among patients with confirmed completed questionnaires (n = 32), decision conflict (p = 0.004) and state anxiety (p = 0.042) decreased significantly from pre- to post-assay. CONCLUSIONS: Individualized risk estimates from the DCIS Score assay provide valuable information to physicians and patients. Post-assay, in response to DCIS Score results, surgeons changed treatment recommendations more often than radiation oncologists. Further investigation is needed to better understand how such treatment changes may affect clinical outcomes.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/radiotherapy , Carcinoma, Intraductal, Noninfiltrating/genetics , Carcinoma, Intraductal, Noninfiltrating/radiotherapy , Gene Expression Profiling , Adult , Aged , Aged, 80 and over , Anxiety/etiology , Breast Neoplasms/surgery , Carcinoma, Intraductal, Noninfiltrating/surgery , Clinical Decision-Making , Conflict, Psychological , Female , Humans , Mastectomy, Segmental , Middle Aged , Practice Patterns, Physicians' , Radiation Oncologists , Radiotherapy, Adjuvant , Risk Assessment/methods , Surgeons , Surveys and QuestionnairesABSTRACT
BACKGROUND AND OBJECTIVES: Twenty percent of breast cancers are ductal carcinoma in situ (DCIS), with 15-60% having a local recurrence (LR) after surgery. Radiotherapy reduces LR by 50% but has not impacted survival. The validated Oncotype DX(®) 12-gene assay (DCIS Score) provides individualized 10-year LR estimates. This is the first study to assess whether DCIS Score impacts physicians' recommendations for radiation. METHODS: Ten sites enrolled women (9/2012-2/2014) with DCIS eligible for breast-conserving therapy, excluding patients with invasive carcinoma and planned mastectomy. Prospective data collected included clinicopathologic factors, DCIS Score assay, and treatment recommendation before and after the assay result was known. RESULTS: In 115 patients (median age: 61 years; 74.8% postmenopausal), median DCIS size was 8 mm; 20% were nuclear grade 1, 46.1% grade 2; 64.4% reported necrosis. 86.1% were ER+, 79.1% PR+ (immunohistochemistry assay). Median DCIS Score: 29 (range: 0-85). Pre-assay, 73% (95%CI: 64.0-80.9%) had radiotherapy recommendations vs. 59.1% (95%CI: 49.6-68.2%) post-assay (P= 0.008). Physicians rated DCIS Score as the most impactful factor in planning treatment. CONCLUSIONS: The radiotherapy recommendation changed from pre-assay to post-assay 31.3% (95%CI: 23.0-40.6%) of the time--a clinically significant change. This study supports the clinical utility of the DCIS Score and indicates that the test provides additional, individualized information on LR risk.
Subject(s)
Breast Neoplasms/genetics , Breast Neoplasms/radiotherapy , Carcinoma, Intraductal, Noninfiltrating/genetics , Carcinoma, Intraductal, Noninfiltrating/radiotherapy , Neoplasm Recurrence, Local , Adult , Aged , Aged, 80 and over , Breast Neoplasms/pathology , Breast Neoplasms/surgery , Carcinoma, Intraductal, Noninfiltrating/pathology , Carcinoma, Intraductal, Noninfiltrating/surgery , Female , Gene Expression Profiling , Humans , Mastectomy, Segmental , Middle Aged , Retrospective Studies , Risk AssessmentABSTRACT
The principal cause of a high mortality rate in mesenteric vein thrombosis (MVT) is a delay in diagnosis. Recent data indicate that the mortality rate is decreasing owing to earlier diagnosis and anticoagulation. The authors examined the treatment profile of MVT to see how the increased use of imaging and early anticoagulation has impacted this process. They retrospectively analyzed the treatment paradigm with acute MVT at one institution over a 10-year period. Twenty-three patients were identified. Data were analyzed using chi-squares and Student's t tests. Twenty-three patients (11 men and 12 women with an average age of 51.74 +/-14.8 years) were identified with acute MVT between the years of 1993 and 2003. Five patients had splenic vein thrombosis, 17 had superior mesenteric vein thrombosis, 1 had inferior mesenteric vein thrombosis, and 12 had portal vein thrombosis. Nine patients had combination mesenteric vein segment thrombosis. Thrombolytics were utilized in a total of 6 patients. Four of the 6 patients in whom lytics were utilized had combined mesenteric vein thrombosis; however, these 4 patients did not require surgical intervention. There was no significant difference in length of hospital stay between patients taking lytics versus patients treated with traditional anticoagulation with heparin (p = 0.291). A hypercoagulable state was identified in 66.7% of the patients. Four patients required surgical intervention. The overall mortality rate was 8.7% (2 of 23). The use of thrombolytics was associated with a significant mortality (p = 0.04). The use of antibiotics made no difference in mortality (p = 0.235), nor did antibiotic use influence length of hospitalization (p = 0.192). MVT is relatively rare, and often the delay in diagnosis increases the mortality rate. In the majority of cases prompt anticoagulation will preserve bowel viability and decrease mortality and morbidity rates. The majority of patients do not need surgery. There is a marked increase in mortality rate when these patients progress to surgical intervention. An increased awareness and early diagnosis has led to decreased morbidity and mortality rates.
Subject(s)
Mesenteric Vascular Occlusion/diagnosis , Mesenteric Vascular Occlusion/therapy , Mesenteric Veins , Thrombectomy/methods , Thrombolytic Therapy/methods , Acute Disease , Adult , Aged , Chi-Square Distribution , Cohort Studies , Early Diagnosis , Female , Follow-Up Studies , Humans , Magnetic Resonance Angiography/methods , Male , Mesenteric Vascular Occlusion/mortality , Middle Aged , Probability , Retrospective Studies , Risk Assessment , Severity of Illness Index , Survival Rate , Tomography, X-Ray Computed , Treatment Outcome , Ultrasonography, DopplerABSTRACT
Currently, 1 per cent isosulfan blue dye and technetium-99-labeled sulfur colloid (SC) are used in lymphatic mapping (LM). Several reports have suggested that the incidence of adverse drug reactions (ADRs) during LM is high. We report our experience with LM for solid neoplasms in order to determine the incidence and risk factors for development of ADRs. Seven hundred fifty-three patients (90% women, mean age 57) underwent LM with blue dye alone or in combination with SC from 1998 to 2004. The most common malignancy was breast cancer (83%). One hundred ten patients (14%) had injection of both mapping agents. Most patients (87%) underwent intraparenchymal injection of LM agent. Eight patients (1.1%) had an ADR during LM; none had prior exposure to LM. Of these, 7 had limited reactions (mostly blue hives) that quickly resolved. One patient (0.1%) developed anaphylaxis. The ADR incidence in patients with a sulfa allergy was not significantly different than that in patients without a sulfa allergy (3.4 vs 1%, P = 0.12). No risk factors for development of ADR were identified. Overall, the incidence of ADR during LM is low. Patients with sulfa allergies and prior exposure to LM did not demonstrate an increased incidence of ADR. Anaphylaxis, though rare, can occur during LM.
Subject(s)
Breast Neoplasms/pathology , Coloring Agents/adverse effects , Drug Hypersensitivity/etiology , Rosaniline Dyes/adverse effects , Sentinel Lymph Node Biopsy/adverse effects , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Lymphatic Metastasis , Male , Middle Aged , Neoplasms/pathology , Retrospective Studies , Risk Factors , Sentinel Lymph Node Biopsy/methodsABSTRACT
Lymphatic mapping (LM) and sentinel lymph node biopsy (SLNB) have become widely accepted in the setting of breast conservation surgery. We hypothesized that LM can be extended to women undergoing total mastectomy, being technically feasible, yielding highly accurate and sensitive results, improving axillary staging, and reducing postoperative morbidity. Between 1995 and 2003, 99 women (mean age 59 years, range 34-87) underwent 100 mastectomies with LM using blue dye alone. Fifty-nine operations (60%) were followed by a completion axillary lymph node dissection (ALND). Ninety per cent of patients had invasive carcinoma; 10 per cent had in situ carcinoma. Mean tumor size was 2.5 cm (range 0.3-8 cm). One hundred fifty-nine sentinel nodes (SNs) (mean 1.65, range 1-5) were successfully identified in 96 (96%) axillae. Twenty-five (25%) sentinel nodes revealed nodal metastases. Five of 25 (20%) SNs had micrometasteses. Three patients had a false-negative SN, yielding a sensitivity of 91 per cent. The accuracy of LM was 97 per cent. No patient who underwent SLNB alone developed lymphedema, axillary seroma formation, infection, or restricted arm movement. This was contrasted with patients undergoing ALND, where 10 (16%) developed lymphedema and 2 (3%) developed an infection. Ten (25%) patients developed axillary paresthesias after SNB compared with 47 (78%) patients after ALND (P < 0.0001). LM in the setting of mastectomy is accurate and sensitive. This technique improves axillary staging and decreases morbidity. Patients who are not candidates for breast conservation should be offered LM and SLNB at the time of mastectomy.
Subject(s)
Breast Neoplasms/pathology , Mastectomy, Simple/classification , Mastectomy, Simple/methods , Postoperative Complications , Sentinel Lymph Node Biopsy/methods , Adult , Aged , Breast Neoplasms/surgery , Female , Humans , Lymphatic Metastasis , Middle Aged , Neoplasm Staging , Sensitivity and Specificity , Treatment OutcomeABSTRACT
Serosanguinous drainage after mastectomy and axillary lymph node dissection has traditionally been treated with the temporary use of closed suction drainage catheters. Use of drainage catheters is associated with wound infection, discomfort, nerve injury, and impaired arm movement. Commercially produced fibrin sealant has been proposed to reduce postoperative serosanguinous collections. We hypothesized that the intraoperative application of low-dose (2-5 cm3) fibrin sealant would reduce serosanguinous drainage and allow earlier removal of closed suction drainage catheters after operation for breast cancer. Fifty-five women with known breast cancer underwent either total mastectomy, modified radical mastectomy, or isolated level I and II axillary lymph node dissection. Twenty-six patients were treated with fibrin sealant and 29 served as control subjects. The application of fibrin sealant resulted in a significant reduction in overall duration catheters were needed (7 vs 8.3 days; P = 0.05). More importantly fibrin sealant reduced the time until 24-hour drain output was less than 30 cm3 (4.9 vs 6.2 days). Additionally fibrin sealant application resulted in a 60 per cent reduction in overall drainage amount after total mastectomy and a 32 per cent reduction after modified radical mastectomy. The application of fibrin sealant after axillary lymph node dissection did not decrease overall drainage amount. In conclusion fibrin sealant reduces serosanguinous drainage after total mastectomy and modified radical mastectomy and may allow earlier removal of closed suction drainage catheters.
Subject(s)
Breast Neoplasms/surgery , Device Removal , Fibrin Tissue Adhesive/administration & dosage , Mastectomy , Postoperative Care , Suction , Tissue Adhesives/administration & dosage , Adult , Aged , Aged, 80 and over , Axilla , Catheterization , Female , Humans , Lymph Node Excision , Mastectomy, Modified Radical , Mastectomy, Simple , Middle Aged , Suction/instrumentationABSTRACT
HYPOTHESIS: Sentinel node (SN) biopsy for breast cancer enhances staging sensitivity, often demonstrating only micrometastases (<2 mm) or isolated, keratin-positive cells. When SN metastasis is present, the value of additional axillary dissection is unclear and not all patients benefit from axillary lymph node dissection (ALND). DESIGN: Prospective cohort study, median 32-month follow-up. SETTING: Multidisciplinary breast cancer centers. PATIENTS: Forty-six women having SN metastases diagnosed between May 1, 1996, and September 1, 2001, who refused ALND or were recommended to omit ALND owing to serious comorbid conditions. INTERVENTIONS: Isosulfan blue dye-directed SN biopsy. Axillary lymph node dissection was not performed. Standard breast irradiation was given. Adjuvant systemic therapy was provided as determined by an oncologist. Interval clinical evaluation was performed. MAIN OUTCOME MEASURE: Axillary and systemic failure rates. RESULTS: Mean patient age was 61.6 years (age range, 36-92 years). Mean tumor size was 1.65 cm (range, 0.4-5.5 cm). Thirty-five (76%) of 46 tumors were ductal carcinomas and 39 (87%) of 45 were estrogen receptor-positive. A mean of 2.6 SNs were identified (median, 2; range, 1-7). Thirty-nine patients (85%) had a single positive SN; the remaining 7 patients (15%) had 2 positive SNs. Seven patients (15%) had macrometastases (>2 mm); 16 (35%) had micrometastases (<2 mm); and 23 (50%) had cellular metastases. Only 16 positive SNs (35%) were seen on hematoxylin-eosin staining, while 30 SNs (65%) had positive immunohistochemical staining. There have been no axillary recurrences. One patient (2%) developed distant metastases during follow-up (range, 4-61 months). CONCLUSIONS: Patients with SN metastases who did not have ALND had a low incidence of regional failure. To confirm this observation, we suggest that patients with SN metastases are ideal candidates for trials evaluating the necessity of ALND.
Subject(s)
Breast Neoplasms/pathology , Breast Neoplasms/surgery , Carcinoma, Ductal, Breast/pathology , Carcinoma, Ductal, Breast/surgery , Lymph Node Excision , Adult , Aged , Aged, 80 and over , Axilla , Breast Neoplasms/metabolism , Carcinoma, Ductal, Breast/metabolism , Cohort Studies , Female , Humans , Lymph Node Excision/methods , Lymph Node Excision/statistics & numerical data , Lymphatic Metastasis , Mastectomy/methods , Middle Aged , Neoplasm Recurrence, Local , Neoplasm Staging , Prospective Studies , Receptors, Estrogen/metabolism , Rosaniline Dyes , Sentinel Lymph Node Biopsy/methodsABSTRACT
PURPOSE: Sentinel lymph node (SLN) biopsy is a widely accepted method for staging breast cancer and melanoma, and it has recently been proposed as a means of improving staging in colorectal cancer. However, lymphatic mapping in colorectal cancer has been plagued by studies demonstrating high false-negative rates. The purpose of this study was to evaluate possible mechanisms for high false-negative rates after SLN biopsy in colorectal cancer. We hypothesized that poor accuracy may be due to bulky tumor or complete replacement of lymph nodes by tumor. PATIENTS AND METHODS: Patients with colorectal adenocarcinoma underwent standard colorectal resection with lymphatic mapping. At operation, 1 mL of isosulfan blue dye was injected at the tumor site, using either an in vivo or an ex vivo technique. Routine pathological evaluation was performed. The sentinel node was examined by hematoxylin and eosin stains, and if these results were negative, by cytokeratin immunohistochemistry. The patient's age, operation type, tumor stage, tumor diameter, method of SLN detection, presence of palpable nodes, and pathological description of nodes completely replaced by tumor were recorded. RESULTS: Fifty patients (mean age, 62.8, 50% men) undergoing colorectal cancer resection underwent 51 lymphatic mapping procedures. Right- and left-sided colorectal resections were almost equally distributed (48% vs 42%). SLNs were successfully identified in 47 of 51 specimens (92%). The mean number of SLNs obtained from each specimen was 1.5 (range, 1-5). Routine pathological evaluation demonstrated lymph node metastasis in 20 of the 47 patients (43%) who had an SLN identified. The SLN was positive for metastasis in 10 of these 20 patients (50%). Ten of 20 patients with metastatic disease had a negative SLN, resulting in a false-negative rate of 50%. The false-negative rate was significantly higher in patients undergoing left-sided procedures versus right-sided procedures. Differences among gender, tumor stage, tumor diameter, method of SLN detection, presence of palpable nodes, and pathological description of nodes completely replaced by tumor were not associated with a higher false-negative rate. DISCUSSION: Identification of the SLN in colorectal cancer is technically possible in more than 90% of patients. However, SLN status correlates poorly with the true nodal status of the colorectal cancer, and the false-negative rate is 50%. This high false-negative rate is not clearly explained by extensive tumor burden, and it was also independent of gender, tumor stage, and type of lymphatic mapping technique. However, staging accuracy was lower in patients who underwent left-sided colorectal resection. Further studies are needed to clarify the limitations of lymphatic mapping in colorectal cancer.