Evaluation of Watchful Waiting and Tumor Behavior in Patients With Basal Cell Carcinoma An Observational Cohort Study of 280 Basal Cell Carcinomas in 89 Patients

IMPORTANCE Few studies have examined watchful waiting (WW) in patients with basal cell carcinoma (BCC), although this approach might be suitable in patients who might not live long enough to benefit from treatment. OBJECTIVE To evaluate reasons for WW and to document the natural course of BCC in patients who chose WW and reasons to initiate later treatment. DESIGN, SETTING, AND PARTICIPANTS An observational cohort study was performed at a single institution between January 2018 and November 2020 studying patients with 1 or more untreated BCC for 3 months or longer. EXPOSURES Watchful waiting was chosen by patients and proxies regardless of this study. MAIN OUTCOME AND MEASURES The reasons for WW and treatment were extracted from patient files and were categorized for analyses. Linear mixed models were used to estimate tumor growth and identify covariates associated with tumor growth. RESULTS Watchful waiting was chosen for 280 BCCs in 89 patients (47 men [53%] and 42 women [47%]), with a median (interquartile range [IQR]) follow-up of 9 (4-15) months. The median (IQR) age of the included patients was 83 (73-88) years. Patient-related factors or preferences (ie, prioritizations of comorbidities, severe frailty, or limited life expectancy) were reasons to initiate WW in 74 (83%) patients, followed by tumor-related factors (n = 49; 55%). Treatment-related and circumstantial reasons were important for 35% and 46% of the patients, respectively. The minority of tumors increased in size (47%). Tumor growth was associated with BCC subtype (odds ratio, 3.35; 95% CI, 1.47-7.96; P = .005), but not with initial tumor size and location. The estimated tumor diameter increase was 4.46 mm (80% prediction interval, 1.42 to 7.46 mm) in 1 year for BCCs containing at least an infiltrative/micronodular component and 1.06 mm (80% prediction interval, -1.79 to 4.28 mm) for the remaining BCCs (only nodular/superficial component/clinical diagnosis). Most common reasons to initiate treatment were tumor burden or potential tumor burden, resolved reason(s) for WW, and reevaluation of patient-related factors. CONCLUSIONS AND RELEVANCE In this cohort study of patients with BCC, WW was an appropriate approach in several patients, especially those with asymptomatic nodular or superficial BCCs and a limited life expectancy. Patients should be followed up regularly to determine whether a WW approach is still suitable and whether patients still prefer WW and to reconsider consequences of treatment and refraining from treatment.