Merkel cell carcinoma recurrence risk estimation is improved by integrating factors beyond cancer stage: A multivariable model and web-based calculator.

BACKGROUND: Merkel cell carcinoma (MCC) recurs in 40% of patients. In addition to stage, factors known to affect recurrence risk include: sex, immunosuppression, unknown primary status, age, site of primary tumor, and time since diagnosis. PURPOSE: Create a multivariable model and web-based calculator to predict MCC recurrence risk more accurately than stage alone. METHODS: Data from 618 patients in a prospective cohort were used in a competing risk regression model to estimate recurrence risk using stage and other factors. RESULTS: In this multivariable model, the most impactful recurrence risk factors were: American Joint Committee on Cancer stage (P < .001), immunosuppression (hazard ratio 2.05; P < .001), male sex (1.59; P = .003) and unknown primary (0.65; P = .064). Compared to stage alone, the model improved prognostic accuracy (concordance index for 2-year risk, 0.66 vs 0.70; P < .001), and modified estimated recurrence risk by up to 4-fold (18% for low-risk stage IIIA vs 78% for high-risk IIIA over 5 years). LIMITATIONS: Lack of an external data set for model validation. CONCLUSION/RELEVANCE: As demonstrated by this multivariable model, accurate recurrence risk prediction requires integration of factors beyond stage. An online calculator based on this model (at merkelcell.org/recur) integrates time since diagnosis and provides new data for optimizing surveillance for MCC patients.

Recurrence and Mortality Risk of Merkel Cell Carcinoma by Cancer Stage and Time From Diagnosis.

IMPORTANCE: Merkel cell carcinoma (MCC) often behaves aggressively; however, disease-recurrence data are not captured in national databases, and it is unclear what proportion of patients with MCC experience a recurrence (estimates vary from 27%-77%). Stage-specific recurrence data that includes time from diagnosis would provide more precise prognostic information and contribute to risk-appropriate clinical surveillance. OBJECTIVE: To estimate risk of stage-specific MCC recurrence and mortality over time since diagnosis. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study included 618 patients with MCC who were prospectively enrolled in a Seattle-based data repository between 2003 and 2019. Of these patients, 223 experienced a recurrence of MCC. Data analysis was performed July 2019 to November 2021. MAIN OUTCOMES AND MEASURES: Stage-specific recurrence and survival, as well as cumulative incidence and Kaplan-Meier analyses. RESULTS: Among the 618 patients included in the analysis (median [range] age, 69 [11-98] years; 227 [37%] female), the 5-year recurrence rate for MCC was 40%. Risk of recurrence in the first year was high (11% for patients with pathologic stage I, 33% for pathologic stage IIA/IIB, 30% for pathologic stage IIIA, 45% for pathologic stage IIIB, and 58% for pathologic stage IV), with 95% of recurrences occurring within the first 3 years. Median follow-up among living patients was 4.3 years. Beyond stage, 4 factors were associated with increased recurrence risk in univariable analyses: immunosuppression (hazard ratio [HR], 2.4; 95% CI, 1.7-3.3; P < .001), male sex (HR, 1.9; 95% CI, 1.4-2.5; P < .001), known primary lesion among patients with clinically detectable nodal disease (HR, 2.3; 95% CI, 1.4-4.0; P = .001), and older age (HR, 1.1; 95% CI, 1.0-1.3; P = .06 for each 10-year increase). Among 187 deaths in the cohort, 121 (65%) were due to MCC. The MCC-specific survival rate was strongly stage dependent (95% at 5 years for patients with pathologic stage I vs 41% for pathologic stage IV). Among patients presenting with stage I to II MCC, a local recurrence (17 arising within/adjacent to the primary tumor scar) did not appreciably diminish survival compared with patients who had no recurrence (85% vs 88% MCC-specific survival at 5 years). CONCLUSIONS AND RELEVANCE: In this cohort study, the MCC recurrence rate (approximately 40%) was notably different than that reported for invasive melanoma (approximately 19%), squamous cell carcinoma (approximately 5%-9%), or basal cell carcinoma (approximately 1%-2%) following definitive therapy. Because more than 90% of MCC recurrences arise within 3 years, it is appropriate to adjust surveillance intensity accordingly. Stage- and time-specific recurrence data can assist in appropriately focusing surveillance resources on patients and time intervals in which recurrence risk is highest.

Histopathologic upgrading of cutaneous squamous cell carcinomas during Mohs micrographic surgery: A retrospective cohort study.

BACKGROUND: Initial biopsies of cutaneous squamous cell carcinomas (cSCCs) may not reveal aggressive histologic features, which would otherwise inform appropriate surgical management and patient education. OBJECTIVE: To assess the incidence of, and risk factors for, histopathologic upgrading of cSCC during Mohs micrographic surgery (MMS). METHODS: This was a retrospective cohort study of invasive cSCCs treated with MMS between 2017 and 2019 at 1 academic institution. An "upgrade" was defined as a lesser degree of differentiation (poor or moderate) and/or bony or perineural invasion identified during MMS that was not reported in histopathologic evaluation of the initial biopsy. RESULTS: Of the 1558 tumors studied, 115 (7.4%) were upgraded during MMS. In multivariate logistic regression analysis, male sex, prior field treatment, location on the ear/lip, rapid growth of cSCC, and tumor diameter ≥2 cm were significant predictors of tumor upgrading. Upgraded tumors were more likely to require ≥3 MMS stages to clear, complicated closure (flap or graft), or outside (referral) repairs. LIMITATIONS: Single-center study, retrospective, and inter-rater variability. CONCLUSIONS: A significant proportion of cSCCs is histopathologically upgraded with more aggressive features during MMS. Routinely documented patient and tumor characteristics can predict tumor upgrading and assist clinicians in directing the management of potentially high-risk cSCC patients.

Clinical benefit of baseline imaging in Merkel cell carcinoma: Analysis of 584 patients.

BACKGROUND: Merkel cell carcinoma (MCC) guidelines derive from melanoma and do not recommend baseline cross-sectional imaging for most patients. However, MCC is more likely to have metastasized at diagnosis than melanoma. OBJECTIVE: To determine how often baseline imaging identifies clinically occult MCC in patients with newly diagnosed disease with and without palpable nodal involvement. METHODS: Analysis of 584 patients with MCC with a cutaneous primary tumor, baseline imaging, no evident distant metastases, and sufficient staging data. RESULTS: Among 492 patients with clinically uninvolved regional nodes, 13.2% had disease upstaged by imaging (8.9% in regional nodes, 4.3% in distant sites). Among 92 patients with clinically involved regional nodes, 10.8% had disease upstaged to distant metastatic disease. Large (>4 cm) and small (<1 cm) primary tumors were both frequently upstaged (29.4% and 7.8%, respectively). Patients who underwent positron emission tomography-computed tomography more often had disease upstaged (16.8% of 352), than those with computed tomography alone (6.9% of 231; P = .0006). LIMITATIONS: This was a retrospective study. CONCLUSIONS: In patients with clinically node-negative disease, baseline imaging showed occult metastatic MCC at a higher rate than reported for melanoma (13.2% vs <1%). Although imaging is already recommended for patients with clinically node-positive MCC, these data suggest that baseline imaging is also indicated for patients with clinically node-negative MCC because upstaging is frequent and markedly alters management and prognosis.

Cost-effectiveness analyses demonstrate that observation is superior to sentinel lymph node biopsy for postmenopausal women with HR + breast cancer and negative axillary ultrasound.

PURPOSE: To evaluate the cost-effectiveness of axillary observation versus sentinel lymph node biopsy (SLNB) after negative axillary ultrasound (AUS). In patients with clinical T1-T2 N0 breast cancer and negative AUS, SLNB is the current standard of care for axillary staging. However, SLNB is costly, invasive, decreasing in importance for medical decision-making, and is not considered therapeutic. Observation alone is currently being evaluated in randomized clinical trials, and is thought to be non-inferior to SLNB for patients with negative AUS. METHODS: We performed cost-effectiveness analyses of observation versus SLNB after negative AUS in postmenopausal women with clinical T1-T2 N0, HR+/HER2- breast cancer. Costs at the 2016 price level were evaluated from a third-party commercial payer perspective using the MarketScan® Database. We compared cost, quality-adjusted life years (QALYs), and net monetary benefit (NMB). Multiple sensitivity analyses varying baseline probabilities, costs, utilities, and willingness-to-pay thresholds were performed. RESULTS: Observation was superior to SLNB for patients with N0 and N1 disease, and for the entire patient population (NMB in US$: $655,659 for observation versus $641,778 for SLNB for the entire patient population). In the N0 and N1 groups, observation incurred lower cost and was associated with greater QALYs. SLNB was superior for patients with > 3 positive lymph nodes, representing approximately 5% of the population. Sensitivity analyses consistently demonstrated that observation is the optimal strategy for AUS-negative patients. CONCLUSION: Considering both cost and effectiveness, observation is superior to SLNB in postmenopausal women with cT1-T2 N0, HR+/HER2- breast cancer and negative AUS.

Patterns of distant metastases in 215 Merkel cell carcinoma patients: Implications for prognosis and surveillance.

Approximately one-third of Merkel cell carcinoma (MCC) patients eventually develop distant metastatic disease. Little is known about whether the location of the primary lesion is predictive of initial distant metastatic site, or if survival likelihood differs depending on the metastatic site. Such data could inform imaging/surveillance practices and improve prognostic accuracy. Multivariate and competing-risk analyses were performed on a cohort of 215 MCC patients with distant metastases, 31% of whom had two or more initial sites of distant metastasis. At time of initial distant metastasis in the 215 patients, metastatic sites (n = 305) included non-regional lymph nodes (present in 41% of patients), skin/body wall (25%), liver (23%), bone (21%), pancreas (8%), lung (7%), and brain (5%). Among the 194 patients who presented with MCC limited to local or regional sites (stage I-III) but who ultimately developed distant metastases, distant progression occurred in 49% by 1 year and in 80% by 2 years following initial diagnosis. Primary MCC locations differed in how likely they were to metastasize to specific organs/sites (P < .001). For example, liver metastases were far more likely from a head/neck primary (43% of 58 patients) versus a lower limb primary (5% of 39 patients; P < .0001). Skin-only distant metastasis was associated with lower MCC-specific mortality as compared to metastases in multiple organs/sites (HR 2.7; P = .003), in the liver (HR 2.1; P = .05), or in distant lymph nodes (HR 2.0; P = .045). These data reflect outcomes before PD1-pathway inhibitor availability, which may positively impact survival. In conclusion, primary MCC location is associated with a pattern of distant spread, which may assist in optimizing surveillance. Because it is linked to survival, the site of initial distant metastasis should be considered when assessing prognosis.