All Renal Mass Patients
Among the 1,977 patients included in this study, 102 were <40, 765 were 40-59, and 1,110 were 60-79 years old. After pathologic review, 244 (12.3%) patients had benign tumors (). The frequency of benign histology was not significantly different among the age groups as benign tumors were noted in 9%, 12%, and 13% of patients <40, 40-59, and 60-79, respectively (p=0.44). However, younger patients were significantly less likely to have oncocytoma which was present in 44%, 60%, and 85% of patients <40, 40-59, and 60-79 years old with benign histology (p<0.001). Malignant histology was present in 1,733 patients including 1,720 (99%) patients who had either clear cell, papillary, chromophobe, collecting duct, multilocular cystic RCC, or RCC not-otherwise specified.
| Table 1Histology for patients with benign renal tumors treated surgically. Data are given as No. (%) |
Patients with RCC
Among the 1,720 patients with RCC, 89 (5%), 672 (39%), and 959 (56%) were <40, 40-59, and 60-79 years old. Clinical and pathologic features for these age groups are detailed in . There were no statistically significant differences in sex, tumor size, primary tumor classification, lymph node involvement, distant metastases at nephrectomy, ipsilateral multifocality, or bilateral synchronous tumors between the three age groups (). However, patients <40 years old were significantly more likely to present with symptomatic tumors compared with patients aged 40-59 or patients aged 60-79 (p=0.028). Symptoms related to the tumor (i.e. local symptoms) were present in 42%, 26%, and 26% of patients <40, 40-59, and 60-79 years old, respectively; however, systemic/constitutional symptoms at presentation were similar across the age groups and noted in 6%, 5%, and 6% of patients <40, 40-59, and 60-79 years old, respectively. Additionally, there were significant differences in histology among the RCC patients by age (p<0.001). Specifically, patients <40 years old (17%) were more likely to have chromophobe histology compared with patients aged 40-59 years old (13%) and patients aged 60-79 years old (8%). In contrast, the frequency of papillary histology increased with age, present in 7%, 13%, and 16% of patients aged <40, 40-59, and 60-79 years old, respectively. The presence of clear cell RCC was similar across the age groups; 69%, 70%, and 72% of patients aged <40, 40-59, and 60-79 years old, respectively.
| Table 2Clinical and pathologic features by age group for patients treated surgically for renal cell carcinoma. Data are given as No. (%) unless otherwise noted. |
Interestingly, despite similar tumor sizes, the percentage of patients treated with partial nephrectomy declined with age (p<0.001); 49% of patients <40 years old received a partial nephrectomy compared with patients aged 40-59 years old (35%) and 60-79 years old (30%). However, the frequency of partial nephrectomy increased in each age group with time. For example, between the years 1990-1994, 1995-1999, and 2000-2005, the frequency of partial nephrectomy for patients <40 years old was 19%, 28%, and 76%, respectively. Similarily, the frequency of partial nephrectomy for patients 60-79 years old during the same time periods was 6%, 17%, and 46%, respectively. For the subset of patients found to have a benign renal mass, the frequency of partial nephrectomy also appeared to decline with age; 67% (6/9) of patients <40 years old received a partial nephrectomy compared with 51% (45/88) of patients 40-59 years old and 48% (71/47) of patients 60-79 years old.
Cancer-Specific Survival for RCC Patients
Among the RCC patients <40, 40-59, and 60-79 years old, 8 (9%), 69 (11 %), and 119 (13%) died from RCC, respectively. Median follow-up for patients still alive at last follow-up was 2.6 years (range 0 - 14) for all patients and was 3.6 years (range 0 - 13), 2.8 years (range 0 - 14), and 2.3 years (range 0 - 14) for patients <40, 40-59, and 60-79 years old, respectively. Cancer-specific survival for patients with RCC by age group is shown in . Estimated cancer-specific survival rates at 5 years for patients <40 years old were 91% compared with 86% for patients 40-59 years old and 85% for patients 60-79 years old (p=0.17 per log-rank test). We also evaluated age as a continuous variable in a univariate Cox model, and age remained not statistically significantly associated with cancer-specific survival (HR 1.13, 95% CI (0.99-1.28) for 10 year increase in age, p=0.07). In a multivariate model adjusting for symptoms at presentation, histology, stage, and type of surgery, age as a continuous variable was not significantly associated with death from disease (HR 1.01, 95% CI .996 - 1.022, p=0.186).