Clinical Stage Migration and Survival for Renal Cell Carcinoma in the United States
Introduction
The incidence of renal cell carcinoma (RCC) has been increasing worldwide for almost 30 yr due to a combination of environmental risk factors and incidental diagnoses attributed to widespread use of cross-sectional imaging [1]. Over 60 000 patients are diagnosed with kidney cancer each year in the USA, and the increased incidence has been accompanied by clinical stage migration toward earlier-stage tumors [2]. Data from the National Cancer Database (NCDB) indicated an increase in the proportion of patients presenting with cT1 RCC from 40% before 1993 to 60% through 2004 [2]. However, it is unknown if clinical stage migration has continued into recent years, which has implications for patient outcomes. Additionally, clinicians continue to quote historical rates of 30–33% for the proportion of patients who present with metastatic RCC, but the accuracy of these estimates is questionable in recent years with one cohort noting a potential dip to <20% in Sweden [3], [4], [5], [6].
Estimates of stage and survival for RCC are often based on rates from the Surveillance, Epidemiology, and End Results program, which reports data on kidney and renal pelvis cancers. Therefore, publicly reported data combine upper tract transitional cell carcinomas with RCC, but the best current estimates suggest that 5-yr overall survival for kidney cancer has increased from 57% in the late 1980s to >70% in recent years; it remains uncertain how much of the increase is due simply to stage migration rather than improvements in providing effective treatment [5]. Management approaches for localized disease are highly effective, so despite implementation of minimally invasive technologies and active surveillance, patient prognosis and cancer control may be unchanged [7], [8]. More promisingly, evidence suggests that patients with metastatic RCC in the targeted therapy era may have improved prognosis [9].
The objective of the present study was to determine whether stage migration has persisted since 2004 and whether survival has improved for patients diagnosed with RCC across >1500 Commission on Cancer facilities. Specifically, we assessed clinical stage at presentation, histologic subtypes, and relative impact on survival that may be attributed to improvements in RCC treatment rather than stage migration.
Section snippets
Patient cohort
The NCDB, jointly sponsored by the American Cancer Society and American College of Surgeons, captures information on the initial diagnosis of malignancy and first course of therapy for patients across >1500 Commission on Cancer facilities in the USA. Patients ≥18 yr of age diagnosed with a malignancy of the kidney or renal pelvis (no exclusion for history of prior malignancies) with data on tumor staging from 2004 to 2015 were evaluated. Of 313 482 patients whose information had been captured,
Stage migration
Of 262 597 patients included from 2004 to 2015, 124 784 (47.5%) had stage I cT1a, 59 787 (22.8%) stage I cT1b, 27 454 (10.5%) stage II, 21 802 (8.3%) stage III, and 28 770 (11.0%) stage IV. Detailed demographics and clinical data are reported in Supplementary Table 1. Stage migration over the 12-yr period is displayed in Figure 1A, with statistically significant trends toward greater diagnosis of clinical stage I RCC (p < 0.001) and decreased diagnosis of clinical stage III (p < 0.001) and stage IV
Discussion
After over 25 yr, RCC stage migration has stabilized and ended according to Commission on Cancer facilities captured by the NCDB in the USA. Early evidence suggested that stage migration began before 1983 when T2 tumors (>7 cm) were more common than either T1a or T1b tumors [11]. Owing to environmental risk factors and use of cross-sectional imaging, the increased incidence of RCC was accompanied by drastic stage migration [1], [2], [12]. The results of the present study demonstrate that stage
Conclusions
The proportion of patients presenting with early-stage (stage I) RCC has stabilized in the USA at about 70% since 2007, suggesting that stage migration may have ended. Localized tumors continue to be detected at a smaller initial size, while tumor size for stage III and IV patients has remained stable, suggesting a need for improved detection of advanced RCC. Only 11% of patients now present with distant metastatic disease, but 5-yr overall survival is improving in recent years likely due to
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