Generative artificial intelligence as a source of breast cancer information for patients: Proceed with caution.

BACKGROUND: This study evaluated the accuracy, clinical concordance, and readability of the chatbot interface generative pretrained transformer (ChatGPT) 3.5 as a source of breast cancer information for patients. METHODS: Twenty questions that patients are likely to ask ChatGPT were identified by breast cancer advocates. These were posed to ChatGPT 3.5 in July 2023 and were repeated three times. Responses were graded in two domains: accuracy (4-point Likert scale, 4 = worst) and clinical concordance (information is clinically similar to physician response; 5-point Likert scale, 5 = not similar at all). The concordance of responses with repetition was estimated using intraclass correlation coefficient (ICC) of word counts. Response readability was calculated using the Flesch Kincaid readability scale. References were requested and verified. RESULTS: The overall average accuracy was 1.88 (range 1.0-3.0; 95% confidence interval [CI], 1.42-1.94), and clinical concordance was 2.79 (range 1.0-5.0; 95% CI, 1.94-3.64). The average word count was 310 words per response (range, 146-441 words per response) with high concordance (ICC, 0.75; 95% CI, 0.59-0.91; p < .001). The average readability was poor at 37.9 (range, 18.0-60.5) with high concordance (ICC, 0.73; 95% CI, 0.57-0.90; p < .001). There was a weak correlation between ease of readability and better clinical concordance (-0.15; p = .025). Accuracy did not correlate with readability (0.05; p = .079). The average number of references was 1.97 (range, 1-4; total, 119). ChatGPT cited peer-reviewed articles only once and often referenced nonexistent websites (41%). CONCLUSIONS: Because ChatGPT 3.5 responses were incorrect 24% of the time and did not provide real references 41% of the time, patients should be cautioned about using ChatGPT for medical information.

Trends in Locoregional Therapy in Older Women with Early-Stage Hormone Receptor-Positive Breast Cancer by Frailty and Life Expectancy.

BACKGROUND: In women ≥ 70 years of age with T1N0 hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer, breast surgery type and omission of axillary surgery or radiation therapy (RT) do not impact overall survival. Although frailty and life expectancy ideally factor into therapy decisions, their impact on therapy receipt is unclear. We sought to identify trends in and factors associated with locoregional therapy type by frailty and life expectancy. METHODS: Women ≥ 70 years of age with T1N0 HR+/HER2- breast cancer diagnosed in the Surveillance, Epidemiology, and End Results (SEER)-Medicare database between 2010 and 2015 were stratified by validated claims-based frailty and life expectancy measures. Therapy trends over time by regimen intensity ('high intensity': lumpectomy + axillary surgery + RT, or mastectomy + axillary surgery; 'moderate intensity': lumpectomy + RT, lumpectomy + axillary surgery, or mastectomy only; or 'low intensity': lumpectomy only) were analyzed. Factors associated with therapy type were identified using generalized linear mixed models. RESULTS: Of 16,188 women, 21.8% were frail, 22.2% had a life expectancy < 5 years, and only 12.3% fulfilled both criteria. In frail women with a life expectancy < 5 years, high-intensity regimens decreased significantly (48.8-31.2%; p < 0.001) over the study period, although in 2015, 30% still received a high-intensity regimen. In adjusted analyses, frailty and life expectancy < 5 years were not associated with breast surgery type but were associated with a lower likelihood of axillary surgery (frailty: odds ratio [OR] 0.86, 95% confidence interval [CI] 0.76-0.96; life expectancy < 5 years: OR 0.22, 95% CI 0.20-0.25). Life expectancy < 5 years was also associated with a lower likelihood of RT receipt in breast-conserving surgery patients (OR 0.30, 95% CI 0.27-0.34). CONCLUSIONS: Rates of high-intensity therapy are decreasing but overtreatment persists in this population. Continued efforts aimed at appropriate de-escalation of locoregional therapy are needed.

Potential Overtreatment of DCIS in Patients with Limited Life Expectancy.

INTRODUCTION: As the benefits of intensive locoregional therapy for ductal carcinoma in situ (DCIS) are realized over time in older adults, life expectancy may help to guide treatment decisions. We examined whether life expectancy was associated with extent of locoregional therapy in this population. PATIENTS AND METHODS: Women ≥ 70 years old with < 5 cm of DCIS diagnosed 2010-2015 were identified in the Surveillance, Epidemiology, and End Results (SEER)-Medicare dataset and categorized by a life expectancy ≤ 5 or > 5 years, defined by a validated claims-based measure. Differences in locoregional therapy (mastectomy + axillary surgery, mastectomy-only, lumpectomy + radiation therapy (RT) + axillary surgery, lumpectomy + RT, lumpectomy-only, and no treatment) by life expectancy were assessed using Pearson chi-squared tests. Generalized linear mixed models were used to identify factors associated with receipt of lumpectomy-only. RESULTS: Of 5346 women (median age of 75 years, range 70-97 years), 927 (17.3%) had a life expectancy ≤ 5 years. Of the 4041 patients who underwent lumpectomy, 710 (13.3%) underwent axillary surgery. More patients with life expectancy ≤ 5 years underwent lumpectomy-only (39.4% versus 27%), mastectomy-only (8.1% versus 5.3%), or no treatment (5.8% versus 3.2%; p < 0.001). On multivariable analysis, women with life expectancy ≤ 5 years had a significantly greater likelihood of undergoing lumpectomy-only [OR 1.90, 95% CI (1.63-2.22)]. CONCLUSIONS: Life expectancy is associated with lower-intensity locoregional therapy for older women with DCIS, yet a large proportion of patients with a life expectancy ≤ 5 years received RT and axillary surgery, highlighting potential overtreatment and opportunities to de-escalate locoregional therapy in older adults.

An Annual Symposium on Disparities in Milwaukee, WI, with a 2023 Focus on Older Adults with Cancer.

PURPOSE OF REVIEW: Cancer-related inequities are prevalent in Wisconsin, with lower survival rates for breast, colorectal, and lung cancer patients from marginalized communities. This manuscript describes the ongoing efforts at the Medical College of Wisconsin and potential pathways of community engagement to promote education and awareness in reducing inequities in cancer care. RECENT FINDINGS: While some cancer inequities are related to aggressive disease biology, health-related social risks may be addressed through community-academic partnerships via an open dialogue between the community members and academic faculty. To develop potential pathways of community-academic partnerships, an annual Cancer Disparities Symposium concept evolved as a pragmatic and sustainable model in an interactive learning environment. In this manuscript, we describe the programmatic development and execution of the annual Cancer Disparities Symposium, followed by highlights from this year's meeting focused on geriatric oncology as discussed by the speakers.

Value of Ambulatory Modified Radical Mastectomy.

BACKGROUND: Modified radical mastectomy (MRM) still is largely performed in inpatient settings. This study sought to determine the value (expenditures and complications) of ambulatory MRM. METHODS: Health Care Utilization Project (HCUP) state databases from 2016 were queried for patients who underwent MRM. The study examined rates of 30-day readmission for surgical-site infection (SSI) or hematoma, charges by index care setting, and predictors of 30-day readmission. RESULTS: Overall, 8090 patients underwent MRM: 5113 (63 %) inpatient and 2977 (37 %) ambulatory patients. Compared with the patients who underwent inpatient MRM, those who underwent ambulatory MRM were older (61 vs. 59 years), more often white (66 % vs. 57 %), in the lowest income quartile (28 % vs. 21 %), insured by Medicare (43 % vs. 33 %) and residents in a small metro area (6 % vs. 4 %) (all p < 0.01). Of the 5113 patients treated as inpatients, 126 (2.5 %) were readmitted, whereas 50 (1.7 %) of the ambulatory patients were readmitted (p = 0.02). The adjusted charge for inpatient MRM without readmission was $113,878 (range, $107,355-120,402) compared with $94,463 (range, $86,021-102,907) for ambulatory MRM, and the charge for inpatient MRM requiring readmission was $159,355 (range, $147,142-171,568) compared with $139,940 (range, $125,808-154,073) for ambulatory MRM (all p < 0.01). This difference remained significant after adjustment for hospital length of stay. Adjusted logistic regression showed that the ambulatory setting was protective for readmission (odds ratio, 0.49; 95 % confidence interval, 0.35-0.70; p < 0.01). CONCLUSIONS: The analyses suggest that ambulatory MRM is both safe and less expensive. The findings advocate that MRM, a last holdout of inpatient care within breast surgical oncology, can be transitioned to the ambulatory setting for appropriate patients.

Screening MRI Does Not Increase Cancer Detection or Result in an Earlier Stage at Diagnosis for Patients with High-Risk Breast Lesions: A Propensity Score Analysis.

BACKGROUND: Guidelines recommend consideration of screening MRI for patients with high-risk breast lesions (HRLs), acknowledging limited data for this moderate-risk population. METHODS: This study identified patients with atypical ductal/lobular hyperplasia (ADH/ALH), lobular carcinoma in situ, (LCIS) or both evaluated at our high-risk clinic. Patients were categorized as having received screening mammography (MMG) alone vs. MMG and breast MRI (MMG+MRI). Inverse probability weighting based on propensity scores (PS) representing likelihood of MRI use was applied to Kaplan-Meier and Cox regression analyses to determine cancer detection and biopsy rates by screening group. RESULTS: Among 908 eligible patients, 699 (77%) patients with available follow-up data were analyzed (542 with ADH/ALH and 157 with LCIS). Of the 699 patients, 540 (77%) received MMG alone, and 159 (23%) received MMG + MRI. The median follow-up period was 25 months, during which a median of two MRIs were performed. After PS-weighting, the characteristics of each screening group were well-balanced with respect to age, race, body mass index (BMI), menopausal status, breast density, family history, HRL type, and chemoprevention use. The 4 year breast cancer detection rate was 3.6% with both MMG alone and MMG+MRI (p = 0.89). The breast biopsy rates were significantly higher with MMG+MRI (30.5% vs12.6%; hazard ratio [HR], 2.67; p < 0.001). All breast cancers were clinically node-negative and pathologic stage 0 or 1. Among five cancers in the MMG+MRI group, two were MRI-detected, two were MMG-detected, and one was detected on clinical exam. CONCLUSIONS: Screening MRI did not improve cancer detection, and cancer characteristics were favorable whether screened with MMG alone or MMG + MRI. These findings question the benefit of MRI for patients with HRL, although longer-term follow-up study is needed.

Association of hospital-level factors with utilization of sentinel lymph node biopsy in patients with early-stage vulvar cancer.

OBJECTIVE: To evaluate utilization of sentinel lymph node biopsy (SLNB) for early-stage vulvar cancer at minority-serving hospitals and low-volume facilities. METHODS: Between 2012-2018, individuals with T1b vulvar squamous cell carcinoma were identified using the National Cancer Database. Patient, facility, and disease characteristics were compared between patients undergoing SLNB or inguinofemoral lymph node dissection (IFLD). Multivariable logistic regression, adjusted for patient, facility, and disease characteristics, was used to evaluate factors associated with SLNB. Kaplan-Meier survival analysis using log rank test and Cox regression was performed. RESULTS: Of the 3,532 patients, 2,406 (68.1%) underwent lymph node evaluation, with 1,704 (48.2%) undergoing IFLD and 702 (19.8%) SLNB. In a multivariable analysis, treatment at minority-serving hospitals (OR 0.39, 95% CI 0.19-0.78) and low-volume hospitals (OR 0.44, 95% CI 0.28-0.70) were associated with significantly lower odds of undergoing SLNB compared to receiving care at non-minority-serving and high-volume hospitals, respectively. While SLNB utilization increased over time for the entire cohort and stratified subgroups, use of the procedure did not increase at minority-serving hospitals. After controlling for patient and tumor characteristics, SLNB was not associated with worse OS compared to IFLD in patients with positive (HR 1.02, 95% CI 0.63-1.66) or negative (HR 0.92, 95% CI 0.70-1.21) nodal pathology. CONCLUSIONS: For patients with early-stage vulvar cancer, treatment at minority-serving or low-volume hospitals was associated with significantly decreased odds of undergoing SLNB. Future efforts should be concentrated toward ensuring that all patients have access to advanced surgical techniques regardless of where they receive their care.

Acceptability of a companion patient guide to support expert consensus guidelines on surveillance mammography in older breast cancer survivors.

PURPOSE: To support shared decision-making, patient-facing resources are needed to complement recently published guidelines on approaches for surveillance mammography in breast cancer survivors aged ≥ 75 or with < 10-year life expectancy. We created a patient guide to facilitate discussions about surveillance mammography in older breast cancer survivors. METHODS: The "Are Mammograms Still Right for Me?" guide estimates future ipsilateral and contralateral breast (in-breast) cancer risks, general health, and the potential benefits/harms of mammography, with prompts for discussion. We conducted in-clinic acceptability testing of the guide by survivors and their clinicians at a National Cancer Institute-designated comprehensive cancer center, including two community practices. Patients and clinicians received the guide ahead of a clinic visit and surveyed patients (pre-/post-visit) and clinicians (post-visit). Acceptability was defined as ≥ 75% of patients and clinicians reporting that the guide (a) should be recommended to others, (b) is clear, (c) is helpful, and (d) contains a suitable amount of information. We also elicited feedback on usability and mammography intentions. RESULTS: We enrolled 45 patients and their 21 clinicians. Among those responding in post-visit surveys, 33/37 (89%) patients and 15/16 (94%) clinicians would recommend the guide to others; 33/37 (89%) patients and 15/16 (94%) clinicians felt everything/most things were clear. All other pre-specified acceptability criteria were met. Most patients reported strong intentions for mammography (100% pre-visit, 98% post-visit). CONCLUSION: Oncology clinicians and older breast cancer survivors found a guide to inform mammography decision-making acceptable and clear. A multisite clinical trial is needed to assess the guide's impact mammography utilization. TRIAL REGISTRATION: ClinicalTrials.gov-NCT03865654, posted March 7, 2019.

Race and Site of Care Impact Treatment Delays in Older Women with Non-Metastatic Breast Cancer.

BACKGROUND: Women ≥ 65 years of age are less likely to receive guideline-concordant breast cancer care. Given existing racial/ethnic disparities, older minority breast cancer patients may be especially prone to inequalities in care. How site of care impacts older breast cancer patients is not well defined. We sought to evaluate the association between race/ethnicity and breast cancer treatment delays in older women treated at minority-serving hospitals (MSHs) versus non-MSHs. METHODS: Women ≥ 65 years of age treated for non-metastatic breast cancer were identified in the National Cancer Database (2010-2017). Treatment delay was defined as > 90 days from diagnosis to initial treatment. MSHs were defined as the top decile of hospitals serving predominantly Black or Hispanic patients. Multivariable logistic regression models adjusted for patient, tumor, and hospital characteristics were used to determine the odds of treatment delay for women at MSHs versus non-MSHs across racial/ethnic groups. RESULTS: Overall, 557,816 women were identified among 41 MSHs and 1146 non-MSHs. Average time to treatment was 33.71 days (standard deviation 26.92 days). Older women at MSHs were more likely to experience treatment delays than those at non-MSHs (odds ratio 1.28, 95% confidence interval 1.21-1.36). Regardless of where they received care, minorities were more likely to experience treatment delays than non-Hispanic White women. CONCLUSIONS: Although 97% of older women treated at Commission on Cancer-accredited hospitals received timely breast cancer care, minorities and those treated at MSHs were more likely to experience treatment delays. Interventions addressing barriers to timely breast cancer care at MSHs may be an effective approach to reducing racial/ethnic disparities.

Variation in Deescalated Axillary Surgical Practices in Older Women with Early-Stage Breast Cancer.

BACKGROUND: Randomized controlled trials show that certain axillary surgical practices can be safely deescalated in older adults with early-stage breast cancer. Hospital volume is often equated with surgical quality, but it is unclear whether this includes performance of low-value surgeries. We sought to describe how utilization of two low-value axillary surgeries has varied by time and hospital volume. METHODS: Women aged ≥ 70 years diagnosed with breast cancer from 2013 to 2016 were identified in the National Cancer Database. The outcomes of interest were sentinel lymph node biopsy (SLNB) in cT1N0 hormone receptor-positive cancer patients and axillary lymph node dissection (ALND) in cT1-2N0 patients undergoing breast-conserving surgery with ≤ 2 pathologically positive nodes. Time trends in procedure use and multivariable regression with restricted cubic splines were performed, adjusting for patient, disease, and hospital factors. RESULTS: Overall, 83.4% of 44,779 women eligible for omission of SLNB underwent SLNB and 20.0% of 7216 patients eligible for omission of ALND underwent ALND. SLNB rates did not change significantly over time and remained significantly different by age group (70-74 years: 93.5%; 75-79 years: 89.7%, 80-84 years: 76.7%, ≥ 85 years: 48.9%; p < 0.05). ALND rates decreased over the study period across all age groups included (22.5 to 16.9%, p < 0.001). In restricted cubic splines models, lower hospital volume was associated with higher likelihood of undergoing SLNB and ALND. CONCLUSIONS: ALND omission has been more widely adopted than SLNB omission in older adults, but lower hospital volume is associated with higher likelihood of both procedures. Practice-specific deimplementation strategies are needed, especially for lower-volume hospitals.

How Often Does Retrieval of a Clipped Lymph Node Change Adjuvant Therapy Recommendations? A Prospective, Consecutive, Patient Cohort Study.

BACKGROUND: Prior studies examining sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) for cN1 patients have demonstrated that 20% of biopsied, clipped lymph nodes (cLNs) are nonsentinel lymph nodes (non-SLNs). Our goal was to determine how often the cLN was a non-SLN among both cN0 and cN1 patients and how often cLN pathology impacted management. METHODS: Overall, 238 patients treated with NAC and surgery January 2019 to June 2020 were prospectively examined. Patients underwent routine axillary ultrasound, biopsy of suspicious nodes, and clip placement. Radioactive iodine-125 seed localization of the cLN was performed in cN1 patients only. Isolated tumor cells (ITCs) were considered node positive (ypN+) for both cN0 and cN1 cohorts. Chart review was performed to determine if cLNs were non-SLN and their ypN status. RESULTS: Of 118 cN0 patients, 115 of 118 (97%) underwent successful SLNB, 33 of whom had a cLN present; 21 of 33 (64%) cLNs were non-SLNs. Overall, 9 of 118 (8%) were ypN+; no cLN was ypN+ without additional +SLNs. Of 120 cN1 patients, 104 of 120 (87%) converted to cN0, 98 of 104 (94%) of which had attempted SLNB, and 95 of 98 (97%) successfully mapped. The cLN was a non-SLN in 18 of 95 (19%). Overall, 58 of 104 (56%) cN1 patients were ypN+. One patient had a positive cLN in the absence of +SLNs. This patient underwent axillary lymph node dissection (ALND); adjuvant treatment recommendations were unchanged. CONCLUSIONS: The cLN was a non-SLN in 19% of cN1 patients. cLN pathology did not impact adjuvant therapy recommendations, calling into question the utility of routinely clipping biopsied lymph nodes.

Cancer in the Shadow of COVID: Early-Stage Breast and Prostate Cancer Patient Perspectives on Surgical Delays Due to COVID-19.

BACKGROUND: During the height of the coronavirus disease 2019 (COVID-19) pandemic, elective surgeries, including oncologic surgeries, were delayed. Little prospective data existed to guide practice, and professional surgical societies issued recommendations grounded mainly in common sense and expert consensus, such as medical therapy for early-stage breast and prostate cancer patients. To understand the patient experience of delay in cancer surgery during the pandemic, we interviewed breast and prostate cancer patients whose surgeries were delayed due to the pandemic. PATIENTS AND METHODS: Patients with early-stage breast or prostate cancer who suffered surgical postponement at Brigham and Women's Hospital (BWH) were invited to participate. Semi-structured telephone interviews were conducted with 21 breast and prostate cancer patients. Interviews were transcribed, and qualitative analysis using ground-theory approach was performed. RESULTS: Most patients reported significant distress due to cancer and COVID. Key themes that emerged included the lack of surprise and acceptance of the surgical delays but endorsed persistent cancer- and delay-related worries. Satisfaction with patient-physician communication and the availability of a delay strategy were key factors in patients' acceptance of the situation; perceived lack of communication prompted a few patients to seek care elsewhere. DISCUSSION: The clinical effect of delay in cancer surgery will take years to fully understand, but there are immediate steps that can be taken to improve the patient experience of delays in care, including elicitation of individual patient perspectives and ongoing communication. More work is needed to understand the wider experiences of patients, especially minority, socioeconomically disadvantaged, and uninsured patients, who encounter delays in oncologic care.

Patient preferences for locoregional therapy in early-stage breast cancer.

PURPOSE: With an increasing emphasis on patient-centered care, clinicians in subspecialties such as breast surgery and radiation oncology that offer multiple therapeutic options with equivalent outcomes are under increasing pressure to aid patients with the decision-making process. The aim of this review is to summarize existing studies that either evaluated factors in patient's decision-making regarding locoregional therapy in early-stage breast cancer or evaluated benefit thresholds required to change therapy decisions. METHODS: A PubMed search to identify prospective or retrospective studies written in English reporting factors in patient decision-making regarding locoregional therapy in early-stage breast cancer was conducted. No restriction was placed on publication date. Studies that focused on breast reconstruction decisions or on patient preferences for decision-making involvement were excluded. RESULTS: A total of 39 studies were identified; 19 examining patient preferences for breast-conserving surgery versus mastectomy, 7 on preferences for contralateral prophylactic mastectomy, 2 on non-surgical options, 2 on the extent of axillary surgery, and 9 on radiation therapy decisions. Themes such as fear of recurrence, desire to avoid additional invasive therapy, and the importance of physician preference were common, but many studies also highlighted factors important to specific subpopulations of women. CONCLUSIONS: Patient preference is difficult to define and measure, and heterogeneity across studies renders direct comparison difficult. Future work is needed to define women's risk-thresholds for certain treatments, delve into the psychological factors that direct their decisions, and understand how patients' valuations of risk interact with society's.

Do Body Mass Index and Breast Density Impact Cancer Risk Among Women with Lobular Carcinoma In Situ?

PURPOSE: Both body mass index (BMI) and breast density impact breast cancer risk in the general population. Whether obesity and density represent additive risk factors in women with lobular carcinoma in situ (LCIS) is unknown. METHODS: Patients diagnosed with LCIS from 1988 to 2017 were identified from a prospectively maintained database. BMI was categorized by World Health Organization classification. Density was captured as the mammographic Breast Imaging Reporting and Data System (BIRADS) value. Other covariates included age at LCIS diagnosis, menopausal status, family history, chemoprevention, and prophylactic mastectomy. Cancer-free probability was estimated using the Kaplan-Meier method, and Cox regression models were used for univariable and multivariable analyses. RESULTS: A total of 1222 women with LCIS were identified. At a median follow-up of 7 years, 179 women developed breast cancer (121 invasive, 58 ductal carcinoma in situ); 5- and 10-year cumulative incidences of breast cancer were 10% and 17%, respectively. In multivariable analysis, increased breast density (BIRADS C/D vs. A/B) was significantly associated with increased hazard of breast cancer (hazard ratio [HR] 2.42, 95% confidence interval [CI] 1.52-3.88), whereas BMI was not. On multivariable analysis, chemoprevention use was associated with a significantly decreased hazard of breast cancer (HR 0.49, 95% CI 0.29-0.84). Exploratory analyses did not demonstrate significant interaction between BMI and menopausal status, BMI and breast density, BMI and chemoprevention use, or breast density and chemoprevention. CONCLUSIONS: Breast cancer risk among women with LCIS is impacted by breast density. These results aid in personalizing risk assessment among women with LCIS and highlight the importance of chemoprevention counseling for risk reduction.

Assessment of hospital-level adjusted breast cancer sentinel lymph node positivity rates.

BACKGROUND/OBJECTIVES: Proficiency of performing sentinel lymph node biopsy (SLNB) for breast cancer varies among hospitals and may be reflected in the hospital's SLNB positivity rate. Our objectives were to examine whether hospital characteristics are associated with variation in SLNB positivity rates and whether hospitals with lower-than-expected SLNB positivity rates have worse patient survival. METHODS: Using the National Cancer Data Base, stage I to III breast cancer patients were identified (2004-2012). Hospital-level SLNB positivity rates were adjusted for tumor and patient factors. Hospitals were divided into terciles of SLNB positivity rates (lower-, higher-, as-expected). Hospital characteristics and survival were examined across terciles. RESULTS: Of 438 610 SLNB patients (from 1357 hospitals), 78 104 had one or more positive SLN (21.3%). Hospitals in the low and high terciles were more likely to be low volume (low: RRR, 4.40; 95% CI, 2.89-6.57; P < 0.001; and high: RRR, 1.79; 95% CI, 1.21-2.64; P < 0.001) compared to hospitals with as-expected (middle tercile) SLNB positivity rates. Stage I patients at low- and high-tercile hospitals had statistically worse survival. CONCLUSIONS: There is a wide variation in hospital SLNB positivity rates. Hospitals with lower- or higher-than-expected SLNB positivity rates were associated with survival differences. Hospital SLNB positivity rates may be a novel 'process measure' to report to hospitals for internal quality assessment.