Observations on the growth rate of renal cell carcinoma

Molecular mechanism of formation and destruction of a pseudo‑capsule in clear cell renal cell carcinoma

The process and molecular mechanisms underlying the formation and destruction of a pseudo-capsule (PC) in clear cell renal cell carcinoma (ccRCC) are poorly understood. In the present study, the PCs of surgical specimens from primary tumors and metastatic lesions in 169 patients with ccRCC, and carcinogen-induced ccRCC rat models were semi-quantified using the invasion of PC (i-Cap) score system. This was based on the relationship among the tumor, PC and adjacent normal tissue (NT) as follows: i-Cap 0, tumor has no PC and does not invade NT; i-Cap 1, tumor has a complete PC and does not invade into the PC; i-Cap 2, tumor with focal absences in the PC, which partially invades the PC but not completely through the PC; i-Cap 3, tumor crosses the PC and invades the NT; i-Cap 4, tumor directly invades the NT without a PC. The study suggested that PC formation was not observed without physical compression, and also revealed that tumor invasion into the PC was a prognostic factor for postoperative oncological outcomes. Higher i-Cap, Fuhrman grade and tumor size were independent poor prognostic factors for postoperative disease-free survival. mRNA expression arrays generated from carcinogen-induced ccRCC rat models were used to explore genes potentially associated with the formation and destruction of a PC. Subsequently, human ccRCC specimens were validated for four genes identified via expression array; the results revealed that collagen type 4A2, matrix metalloproteinase-7 and l-selectin were upregulated alongside the progression of i-Cap score. Conversely, endoglin was downregulated. In conclusion, the present study provides insights into the formation and destruction of a PC, and the results may aid the treatment and management of patients with ccRCC.

Renal cell carcinoma suspected at time of organ donation 2008-2016: A report of the OPTN ad hoc Disease Transmission Advisory Committee Registry

All 179 reports to the OPTN of potential renal cell carcinoma (RCC) transmission from 1/1/2008 through 12/31/2016 were reviewed. Cases were divided into those with donor tumor known or suspected at time of transplant (N = 147 donors), and those in which tumor was initially found after transplant (N = 32). We sought to understand the risk of transplanting either the affected kidney, the contralateral kidney or non-renal organs from donors with a suspected/confirmed unilateral RCC. In the case of RCC found prior to transplant, transplantation of 21 kidneys following excision of tumor, 47 contralateral kidneys and 198 non-renal organs was performed. No cases of RCC transmission were documented in this population. An additional six cases of live donor kidney transplantation involving resection of RCC were reported, also without transmission. Six of 9 other recipients in whom the diagnosis of RCC became available after implantation underwent allograft nephrectomy and 3 received tumor resection. No recurrent RCC was documented. Given the low rate of transmission and available treatment options, consideration should be given to judicious use of organs from donors with small solitary RCC.

Estimation of Solid Tumor Doubling Times from Progression-Free Survival Plots Using a Novel Statistical Approach

Tumor doubling time can significantly affect the outcome of anticancer therapy, but it is very challenging to determine. Here, we present a statistical approach that extracts doubling times from progression-free survival (PFS) plots, which inherently contains information regarding the growth of solid tumors. Twelve cancers were investigated and multiple PFS plots were evaluated for each type. The PFS plot showing fastest tumor growth was deemed to best represent the inherent growth kinetics of the solid tumor, and selected for further analysis. The exponential tumor growth rates were extracted from each PFS plot, along with associated variabilities, which ultimately allowed for the estimation of solid tumor doubling times. The mean simulated doubling times for pancreatic cancer, melanoma, hepatocellular carcinoma (HCC), renal cell carcinoma, triple negative breast cancer, non-small cell lung cancer, hormone receptor positive (HR+) breast cancer, human epidermal growth factor receptor-2 positive (HER-2+) breast cancer, gastric cancer, glioblastoma multiforme, colorectal cancer, and prostate cancer were 5.06, 3.78, 3.06, 2.67, 2.38, 2.40, 4.31, 4.12, and 3.84 months, respectively. For all cancers, clinically reported doubling times were within the estimated ranges. For all cancers, except HCC, the growth rates were best characterized by a log-normal distribution. For HCC, the gamma distribution best described the data. The statistical approach presented here provides a qualified method for extracting tumor growth rates and doubling times from PFS plots. It also allows estimation of the distributional characteristics for tumor growth rates and doubling times in a given patient population.

Natural history of small renal masses

Objective:

To review the natural history and growth kinetics of small renal masses (SRMs).

Data Sources:

The literature concerning natural history and growth kinetics of SRMs was collected from PubMed published from 1990 to 2014.

Study Selection:

We included all the relevant articles on the active surveillance (AS) or delayed treatment for SRMs in English, with no limitation of study design.

Results:

SRMs under AS have a slow growth potential in general. The mean linear growth rate is 0.33 cm/year, the mean volumetric growth rate is 9.48 cm³/year. The rate of metastasis during AS is below 2%. Some factors are associated with the growth rate of SRMs, including tumor grade, histological subtype, initial tumor size, age, radiographic characteristics, and molecular markers. No definite predictor of growth rate of SRMs is defined at present. SRMs with high tumor grade and the subtype of clear cell renal cell carcinoma may have aggressive growth potential.

Conclusions:

AS is a reasonable choice for elderly patients with SRMs, who are at high risk from surgery. Progression during observation is the biggest concern while performing AS. There is no definite predictor of progression for SRMs under AS. Percutaneous renal biopsy providing immunohistological and genic biomarkers may improve the understanding of natural history of SRMs.

Growth Pattern of Clear Cell Renal Cell Carcinoma in Patients with Delayed Surgical Intervention: Fast Growth Rate Correlates with High Grade and May Result in Poor Prognosis

Objectives. Previous studies revealed an unclear correlation between the growth rate of renal cell carcinoma (RCC) and tumor grade and did not focus on certain histological subtype. This report investigated the correlation between the growth rate and tumor grade in clear cell RCC (ccRCC). Methods. We reviewed 60 patients with 61 ccRCC confirmed by delayed surgeries after at least 12 months of active surveillance. The linear growth rate (LGR), volumetric growth rate (VGR), and volume doubling time (VDT) were calculated, and their correlations with clinicopathologic characteristics were analyzed. Results. The mean LGR, VGR, and VDT were 0.86 (range 0–4.74) cm/year, 20.96 (range 0.31–211.93) cm³/year, and 667 (range 33–3321) days, respectively. ccRCCs with high grade had greater LGR (P < 0.001) and VGR (P = 0.001) and lower VDT (P = 0.017) than ccRCCs with low grade. Grade (OR = 5.185, P = 0.004) was the only independent risk factor of LGR >0.5 cm/year, and grade (OR = 3.006, P = 0.046) and initial size (OR = 0.392, P = 0.004) were independent risk factors of VDT <1 year. Five patients developed metastasis after surgery with LGR >0.5 cm/yr altogether; of them, four had cancer-related death by the last follow-up. Conclusions. Fast growth rate of ccRCC is significantly correlated with high tumor grade and may result in poor prognosis, especially for those with LGR >0.5 cm/yr.

Growth kinetics and active surveillance for small renal masses

PURPOSE OF REVIEW

Management options for small renal masses (SRMs) include excision, ablation, and active surveillance. Increasing interest in active surveillance, particularly for tumors of limited oncologic potential, in patients with other significant health concerns continues to rise, but precise protocols are still lacking.

RECENT FINDINGS

A review of 18 retrospective series of patients undergoing active surveillance for 957 SRMs indicates that the majority grew during observation (mean 0.32  cm/year), but only 1.4% metastasized during 32 months of follow-up (median). One published prospective series of 209 SRMs reported average growth of 0.13  cm/year and only 1% metastasized. Maximal tumor diameter (or volume) at presentation is a predictor of growth rate, high-grade disease, and likelihood of metastasis. SRMs less than 3  cm are very unlikely to metastasize and deferring treatment has not been associated with increased failure to cure.

SUMMARY

Active surveillance is a reasonable initial strategy in most patients with SRMs, particularly those with limited life-expectancy and increased perioperative risk. Intervention should be considered for growth to greater than 3-4  cm or by greater than 0.4-0.5  cm/year while on active surveillance.

Growth pattern of renal cell carcinoma (RCC) in patients with delayed surgical intervention

PURPOSE

Few studies have evaluated the growth pattern of renal cell carcinoma (RCC) in patients with delayed treatment. This report investigated the growth rate and stage progression of incidentally discovered RCC following a long period of active surveillance.

METHODS

Thirty-two patients who did not receive immediate surgical treatment for renal solid masses that later proved to be RCC were reviewed retrospectively. Annual tumor growth rates were calculated according to changes in the maximal diameter on CT or MRI. Clinical and pathological characteristics associated with tumor growth rate and stage progression were analyzed.

RESULTS

The median tumor size grow from 2.14 (range, 0.30-6.70) cm to 4.33 (range, 1.40-8.80) cm after a median 46.0 months observation period. The average tumor growth rate was 0.80 (range, 0.16-3.80) cm/year. Clear cell carcinoma (0.86 cm/year) tended to grow faster than papillary cell carcinoma (0.28 cm/year) (P = 0.066). The mean growth rate of grade 2 tumors (0.88 cm/year) was faster than that of grade 1 tumors (0.36 cm/year) (P = 0.041). Thirteen tumors (40.6%) were upstaged at a median 48 months after initial presentation. Cox regression analysis revealed initial tumor size as the only risk factor for upstaging (P = 0.018). No local and systemic recurrences were noted in our cohort after the intervention at a median of 47 (range, 6-248) months of follow-up.

CONCLUSIONS

RCCs were found to be slow growing in a group of untreated renal cell carcinoma patients. However, some tumors progressed in stage under observation. The growth rate of RCC tended to correlate with histologic grade and histologic subtype.

Active surveillance: a potential strategy for select patients with small renal masses

Increased abdominal imaging has led to the significant incidental detection of clinically localized renal masses. While the gold standard remains surgical excision, mortality rates from kidney cancer remain relatively unchanged implying that a proportion of small renal masses may be indolent tumors that do not require surgical intervention. As a result, active surveillance has emerged as an alternative management strategy in select patients with significant competing risks. Although the contemporary literature characterizing the natural history of untreated small renal masses is limited, recent data demonstrate that many incidental renal masses demonstrate slow growth kinetics with a low rate of progression to metastatic disease over an intermediate time period. Prospective trials are necessary to define entry and intervention criteria for active surveillance protocols.

Small renal masses progressing to metastases under active surveillance: a systematic review and pooled analysis

BACKGROUND

The authors systematically reviewed the literature and conducted a pooled analysis of studies on small renal masses who underwent active surveillance to identify the risk progression and the characteristics associated with metastases.

METHODS

A search of the MEDLINE database was performed to identify all clinical series that reported the surveillance of localized renal masses. For studies that reported individual-level data, clinical and radiographic characteristics of tumors without progression were compared with the characteristics of tumors that progressed to metastases.

RESULTS

Eighteen series (880 patients, 936 masses) met screening criteria; and, among these, 18 patients were identified who had tumors that progressed to metastasis (mean, 40.2 months). Six studies (259 patients, 284 masses) provided individual-level data for pooled analysis. At a mean (± standard deviation) follow-up of 33.5 ± 22.6 months, the mean initial greatest tumor dimension was 2.3 ± 1.3 cm, and mean linear growth rate was 0.31 ± 0.38 cm per year. Sixty-five masses (23%) exhibited zero net growth under surveillance, and none of those masses progressed to metastasis. A pooled analysis revealed increased age (age 75.1 ± 9.1 years vs 66.6 ± 12.3 years; P = .03), an initial greatest tumor dimension (4.1 ± 2.1 cm vs 2.3 ± 1.3 cm; P < .0001), initial estimated tumor volume (66.3 ± 100.0 cm(3) vs 15.1 ± 60.3 cm(3) ; p = .0001), linear growth rate of (0.8 ± 0.65 cm per year vs 0.3 ± 0.4 cm per year; P = .0001), and a volumetric growth rate of 27.1 ± 24.9 cm(3) per year (vs 6.2 ± 27.5 cm(3) per year; P < .0001) in the progression cohort.

CONCLUSIONS

A substantial proportion of small renal masses remained radiographically static after an initial period of active surveillance. Progression to metastases occurred in a small percentage of patients and generally was a late event. The current results indicated that, in patients who have competing health risks, radiographic surveillance may be an acceptable initial approach, and delayed intervention may be reserved for patients who have tumors that exhibit significant linear or volumetric growth.

Active surveillance of renal cortical neoplasms: a contemporary review

INTRODUCTION

Over the past 2 decades, there has been a significant increase in the number of incidentally found small renal cortical neoplasms (RCNs). As more RCNs are being discovered in the elderly and infirmed patient populations, there has been a growing interest in the role of active surveillance (AS). Active surveillance is recommended for high surgical-risk patients and those with a reduced life expectancy. It is also an option for patients wishing to avoid surgery. We review the current literature on AS and highlight the natural history of disease, the important factors to evaluate during AS, and the contemporary role of biopsy.

METHODS AND MATERIALS

The MEDLINE database was searched using PubMed. Search terms included active surveillance, renal mass, natural history, and renal mass histology. From 1966 to present, 17 AS series were identified, all of which have been included in this summary. A summary was performed by compiling all available data and performing a weighted mean where applicable.

RESULTS

Initial tumor size does not correlate with growth rate or malignancy. The mean growth rate in large published series is low (0.28-0.34 cm/year). Tumors with high growth rates usually represent malignant lesions and typically undergo delayed intervention. Progression to metatatic disease is a low-probability event for tumors on AS (1.4%); however, this is still a risk that patients must be willing to accept. Larger tumors (cT1b and cT2) also demonstrate relatively low growth (0.57 cm/year); however, these tumors should be monitored carefully. Tumors followed for > 5 years demonstrate a low growth rate (0.15 cm/year), will not likely require intervention, and have a low chance of progression to metastatic disease.

CONCLUSION

For highly selected patients with RCN, AS is a reasonable treatment option. Age, surgical risk, comorbidities, and patient opinion must all factor into the final decision when considering a patient for AS.

A Huge Renal Cell Carcinoma, Nine Years after Its Primary Diagnosis and Obligate Observation

The clinical diagnosis of renal cell carcinoma (RCC) is radiographic. Effective imaging of the kidneys can be achieved by ultrasound, CT or MRI [Chawla et al.: J Urol 2006;175:425–431]. Solid lesions detected by ultrasound and those showing enhancement on cross-sectional imaging are considered malignant until proven otherwise. The standard of care for clinically localized RCC remains surgical resection due to the favorable prognosis associated with surgery and the relative ineffectiveness of systemic therapy. Since patients with localized RCC are often symptom-free, they sometimes refuse to receive surgical treatment or are left untreated based on a diagnosis of benign lesions. There are also cases where an RCC is relatively large and causes symptoms but is not treated surgically because of complications and other reasons. We report a 54-year-old male who underwent a difficult radical nephrectomy 9 years after the primary RCC malignancy diagnosis.

Active surveillance for renal cortical neoplasms

PURPOSE

We retrospectively evaluated our single center experience with patients with renal cortical neoplasms who elected active surveillance.

MATERIALS AND METHODS

We retrospectively evaluated our urological oncology database between January 1993 and January 2009, identifying a total of 223 renal cortical neoplasms in 212 patients that were initially managed by active surveillance. We described patient and tumor characteristics, and assessed the differences between patients who remained on AS and those who underwent delayed intervention or progressed with metastasis.

RESULTS

Median patient age was 71 years at active surveillance initiation and the median Charlson comorbidity index was 3. Median tumor size was 2.8 cm (range 0.5 to 13.7) at study enrollment and 3.7 cm (range 0.9 to 14.1) at final assessment. The median growth rate in the entire cohort was 0.34 cm per year (range 0.29 to 2.3). Median followup was 35 months (range 6 to 137). Active surveillance failed in 15 patients (7%), of whom 4 (2%) progressed to metastasis and 11 (5%) required intervention. When comparing cases of failed active surveillance with those that continued, there were statistical differences in initial tumor size (2.61 vs 3.64 cm, p = 0.019), final tumor size (3.56 vs 5.17 cm, p = 0.001) and growth rate (0.34 vs 1.75, p = 0.001). There was no correlation between initial tumor size and growth rate (Pearson's coefficient r = 0.006, p = 0.932). A total of 14 patients died of another medical condition. Only 1 cancer related death (0.5%) was reported in the entire cohort.

CONCLUSIONS

Active surveillance for renal cortical neoplasms in select older patients with comorbidities is a reasonable treatment option. At 3-year followup we noted a 7% failure rate.

Natural history and management of small renal masses

The recent stage migration observed for renal tumours is contributing to a significant increase in the diagnosis of small renal masses. This evolution has led to a significant change in the approach to renal masses. New options such as observation or energy ablation are gaining popularity in a subset of this patient population. In addition, the observed changes directly contribute to the increased use of nephron-sparing surgery. A better understanding of the various characteristics of these masses will allow for a better understanding of the natural history of these masses and for selection of the optimal therapeutic approach.

Surveillance as an option for the treatment of small renal masses

OBJECTIVES. To review the natural history and biological potential of small renal masses in order to evaluate surveillance as a treatment option. METHODS. Literature search of Medline and additional references from non-Medline-indexed publications concerning surveillance of small renal masses. RESULTS. The natural history and biological potential of small renal masses can still not be unambiguously predicted at present. There seems to be no clear correlation between tumour size and presence of benign histology. The majority of small renal masses grow and the majority are cancer, but one cannot safely assume that a lack of growth on serial CT scans is the confirmation of absence of malignancy. Needle core biopsies could be used to help in decision making. They show a high accuracy for histopathological tumour type but are less accurate in evaluating Fuhrman grade. CONCLUSIONS. At present, surveillance of small renal masses should only be considered in elderly and/or infirm patients with competing health risks, in those with a limited life expectancy, and in those for whom minimal invasive treatment or surgery is not an option. In all other patients, active surveillance should only be considered in the context of a study protocol. Long-term, prospective studies are needed to provide a more accurate assessment of the natural history and metastastic potential of small renal masses.

Renal tumor natural history: the rationale and role for active surveillance

Renal cell carcinoma (RCC) is the most common malignancy of the kidney. Despite widespread treatment at diagnosis, overall mortality rates associated with RCC have not decreased. Partly because of the more frequent use of abdominal imaging, diagnosis as an incidental finding has increased. The largest increase in incidence is in tumors smaller than 4 cm, termed small renal masses (SRMs). SRMs that are RCC may frequently be growth slowly and have a low risk of early progression. Initial active surveillance with delayed treatment for progression for selected patients should be considered. This should result in an overall decrease in treatment burden and cost saving.

A population-based comparison of survival after nephrectomy vs nonsurgical management for small renal masses

OBJECTIVE

To examine population-based rates of cancer-specific and other-cause mortality after either non-surgical management (NSM) or nephrectomy, in patients with small renal masses, as several reports from selected institutions support the applicability of surveillance in patients with small renal masses, but there are no population-based studies confirming the general applicability of this therapy.

PATIENTS AND METHODS

Of 43 143 patients with renal cell carcinoma identified in the 1988-2004 Surveillance, Epidemiology and End Results database, 10 291 had localized small renal masses (<or=4 cm) and were offered NSM (433, 4.2%) or nephrectomy (9858, 95.8%). Univariable matched and multivariable unmatched competing-risks regression models were used in the analyses.

RESULTS

Cumulative incidence plots based on unmatched data, where the effect of other-cause mortality was controlled for, showed a 5.2%, 6.5% and 9.4% survival benefit for nephrectomy vs NSM at 1, 2 and 5 years after nephrectomy or diagnosis, respectively. The same magnitude of the benefit (4.5%, 5.6% and 8.0%) persisted in analyses matched for age, tumour size and year of diagnosis or of nephrectomy. Finally, in multivariable analyses, treatment type, age, tumour size and year of diagnosis or of nephrectomy were independent predictors.

CONCLUSION

Relative to nephrectomy, NSM appears to undermine the overall and cancer-specific survival of patients with small renal masses by as much as 9.4%, at 5 years.

Distribution of renal tumor growth rates determined by using serial volumetric CT measurements

PURPOSE

To retrospectively determine the distribution of growth rates across different sizes and subtypes of renal cortical tumors by assessing tumor volume and maximum tumor diameter at serial volumetric computed tomographic (CT) examinations.

MATERIALS AND METHODS

The institutional review board approved this retrospective, HIPAA-compliant study. Fifty-three of 2304 patients (34 men, 19 women; mean age, 67 years +/- 10 [standard deviation; range, 39-88 years) who underwent nephrectomy from 1989 to 2006 did not receive preoperative chemotherapy or radiation therapy and underwent at least two preoperative contrast material-enhanced CT examinations (at least 3 months apart) with identical section thickness that was no more than one-fifth of longitudinal tumor diameter. Tumor volume and maximum diameter were measured on CT scans. Reciprocal of doubling time (DT) (RDT) was calculated. Analysis of variance and Student t tests were performed.

RESULTS

Thirty-two clear cell carcinomas, 10 papillary carcinomas, six chromophobe carcinomas, four oncocytomas, and one angiomyolipoma were analyzed. Median tumor size was 2.9 cm (range, 1-12 cm). Seven tumors did not increase in volume. DT ranged from -78476.54 to 18057.43 days (mean, -1230.73 days; median, 590.51 days). [corrected] Growth rate determined by using maximum diameter ranged from -10.8 to 33.2 mm/y (mean, 5.1 mm/y; median, 3.5 mm/y). Faster-growing tumors were more likely to be clear cell carcinomas, those of higher grade had higher growth rates. No significant correlation was found between RDT and tumor initial volume, subtype, or grade. Small renal tumors (<or=3.5 cm) were similar to larger tumors in subtype and growth rate. Age at diagnosis correlated negatively with renal tumor growth rate (P = .03).

CONCLUSION

Growth rates in renal tumors of different sizes, subtypes, and grades represent a wide range and overlap substantially. Small renal tumors appear to be similar to larger ones in nature.

Analysis of gene expression in a developmental context emphasizes distinct biological leitmotifs in human cancers

BACKGROUND

In recent years, the molecular underpinnings of the long-observed resemblance between neoplastic and immature tissue have begun to emerge. Genome-wide transcriptional profiling has revealed similar gene expression signatures in several tumor types and early developmental stages of their tissue of origin. However, it remains unclear whether such a relationship is a universal feature of malignancy, whether heterogeneities exist in the developmental component of different tumor types and to which degree the resemblance between cancer and development is a tissue-specific phenomenon.

RESULTS

We defined a developmental landscape by summarizing the main features of ten developmental time courses and projected gene expression from a variety of human tumor types onto this landscape. This comparison demonstrates a clear imprint of developmental gene expression in a wide range of tumors and with respect to different, even non-cognate developmental backgrounds. Our analysis reveals three classes of cancers with developmentally distinct transcriptional patterns. We characterize the biological processes dominating these classes and validate the class distinction with respect to a new time series of murine embryonic lung development. Finally, we identify a set of genes that are upregulated in most cancers and we show that this signature is active in early development.

CONCLUSION

This systematic and quantitative overview of the relationship between the neoplastic and developmental transcriptome spanning dozens of tissues provides a reliable outline of global trends in cancer gene expression, reveals potentially clinically relevant differences in the gene expression of different cancer types and represents a reference framework for interpretation of smaller-scale functional studies.

Active surveillance of renal masses in elderly patients

PURPOSE

We identify and report on a large number of patients treated with active surveillance for incidentally diagnosed renal masses at our institution.

MATERIALS AND METHODS

We identified all patients 75 years or older evaluated in our department for a renal mass between January 2000 and December 2006. A total of 110 patients with enhancing renal masses were initially treated with active surveillance and this group made up the cohort for our study. Medical records were reviewed for clinical and radiological followup, and vital status was obtained from the Social Security Death Index. Clinical and radiographic followup was available for review on 104 and 89 patients, respectively.

RESULTS

Patients had a median age of 81 years (range 76 to 95) with a median Charlson comorbidity index of 2 (range 0 to 7) at diagnosis. Patients had as many as 9 tumors being followed (median of 1) with a median tumor size of 2.5 cm (range 0.9 to 11.2). During a median followup of 24 months (range 1 to 90) mean tumor growth rate was 0.26 cm per year. Of the 89 patients with radiological followup 38 (43%) exhibited no tumor growth on active surveillance. Comparison of the clinical and radiographic features of patients with tumor growth and those with stable disease revealed no statistical differences. Four patients (3.6%) were treated as a result of disease progression 12 to 54 months after diagnosis. At the conclusion of the study 34 patients (31%) were deceased. To our knowledge the renal mass did not contribute to the cause of death in any patient.

CONCLUSIONS

Active surveillance of incidental renal masses appears to be a viable option for older patients with multiple medical comorbidities and a limited life expectancy.

[What may be the waiting time between the diagnosis and surgical treatment of kidney cancer?]

When announcing the diagnosis of renal cell carcinoma, the urologist and the patient can wonder about the waiting time for surgically treating the cancer. This review aimed to investigate the scientific facts to determine the time between the diagnosis of kidney cancer and the achievement of surgically. The natural history of kidney cancer has been the fundamental of the therapeutic management. The time between diagnosis and surgical treatment depends on the conditions under which the diagnosis was established. Patients with symptomatic cancer or discovered at metastatic stage had to be treated quickly. In case of incidental diagnosis, evaluation of tumors has resulted in the selection of patients who can wait several months between diagnosis and surgical treatment of kidney cancer on the condition watchful waiting. The modalities of this assessment, radiological and anatomopathological, must be validated by further studies.

Is Surveillance an Option for the Treatment of Small Renal Masses?

OBJECTIVES

To review the natural history and biological potential of small renal masses in order to evaluate whether surveillance is an option for treatment of small renal masses.

METHODS

Literature search of MEDLINE and additional references from non-MEDLINE-indexed publications concerning surveillance of small renal masses.

RESULTS

Because approximately 26-33% of observed small renal masses do not show radiographic growth, it has been suggested that a brief period of active surveillance may be feasible for selected renal masses, with treatment limited to tumours showing growth. Even though tumour growth might be absent or slow, a proportion of these tumours will express significant malignant behaviour. The biological behaviour of a tumour cannot be unambiguously predicted at present. Surveillance of small renal masses should only be considered in elderly and/or infirm patients with competing health risks, in those with limited life expectancy, and in those for whom surgery is not an option. In all other patients, active surveillance can be considered in the context of a study protocol only. In the majority of the patients, nephron-sparing surgery remains the gold standard treatment.

CONCLUSIONS

Surveillance should only be considered as an alternative to surgery for the treatment of small renal masses in selected patients. It should always be combined with close follow-up imaging and should be allowed only when the patient and the urologist accept the calculated risk. Long-term, prospective studies are needed to provide a more accurate assessment of the natural history and metastastic potential of small renal masses.

Enhancing renal masses with zero net growth during active surveillance

PURPOSE

The natural history of small renal masses is generally to slowly increase in size. However, a subset of lesions does not show radiographic growth. We compared clinical, radiographic and pathological characteristics of enhancing renal masses under active surveillance with zero net radiographic growth vs those with positive growth.

MATERIALS AND METHODS

We identified 106 enhancing renal masses that were observed for 12 months or greater. Lesions were grouped according to growth characteristics. Group 1 consisted of lesions demonstrating zero or negative growth. Group 2 tumors showed positive growth during surveillance. Clinical, radiographic and pathological parameters were then compared. A MEDLINE search was performed regarding zero growth lesions during observation for suspected renal cell carcinoma in the world literature.

RESULTS

Group 1 consisted of 35 lesions (33%) with a median growth rate of 0.0 cm yearly. Group 2 included 70 lesions (67%) showing growth at 0.31 cm yearly (p<0.0001). No differences were detected with regard to patient age (p=0.96), lesion size (p=0.41), solid/cystic appearance (p=1.00) or the incidental detection rate (p=0.38). While 17% of group 1 lesions (6 of 35) underwent intervention, 51% (36 of 71) in group 2 were ultimately treated (p=0.001). Pathological assessment showed a similar incidence of malignancy in groups 1 and 2 (83% and 89%, respectively, p=0.56). A literature review revealed that 78 of 295 observed lesions (26%) failed to demonstrate radiographic growth.

CONCLUSIONS

We were unable to identify definable clinical characteristics to predict the future growth of enhancing renal masses under active surveillance. Our analysis demonstrated that 26% to 33% of these tumors do not demonstrate growth at 29 months median followup. These lesions have similar rates of malignancy compared to growing lesions and rates of progression to metastatic disease are similarly low. A brief period of active surveillance may be feasible with treatment limited to lesions that increase in size.

Growth rates of renal cell carcinoma and oncocytoma under surveillance are similar

OBJECTIVE

Through examining our experience with renal mass surveillance, we hoped to determine factors suggestive of renal cell carcinoma.

METHODS

We followed for at least 1 year 41 patients with 47 solid renal masses (mean diameter 2.0 cm, range 0.8-5). Mean surveillance duration was 29 months and was more than 2 years for 23 masses (49%).

RESULTS

Overall mean increase in diameter was 0.27 cm/year, but 21 (45%) did not grow, and mean growth rate was 0.5 cm/year in the 26 that did grow. Of the masses, 14 have been treated, 33 continue to be followed, and pathology is known in 16 (34%). Growth was seen in all 6 known oncocytomas (mean 0.52 cm/year), 80% of the 10 biopsy proven renal cell carcinomas grew (mean 0.71 cm/year), but only 12 (39%) of the masses with unknown pathology (0.08 cm/year). There was no factor that distinguished oncocytomas from renal cell carcinomas. In 1 patient, a 3-cm mass that had not changed in size for 6 years doubled in size over 6 months, and metastatic disease developed.

CONCLUSIONS

Although growth of most renal masses is slow, some grow quickly, and delayed growth with metastases can occur. No factor distinguished renal cell carcinomas from oncocytomas. Surveillance for renal masses remains an option but must be rigorous and continuous, and is not without risk of progression.

The natural history of observed enhancing renal masses: meta-analysis and review of the world literature

PURPOSE

Standard therapy for an enhancing renal mass is surgical. However, operative treatment may not be plausible in all clinical circumstances. Data on the natural history of untreated enhancing renal lesions is limited but could serve as a decision making resource for patients and physicians. We examined available data on the natural history of observed solid renal masses.

MATERIALS AND METHODS

A Medline review of the literature was performed from 1966 to the present regarding untreated, observed, localized solid renal masses. To these data we added our institutional experience with a total of 61 lesions observed in 49 patients for a minimum of 1 year. Variables examined were initial lesion size at presentation, growth rate, duration of followup, pathological findings and progression to metastatic disease. Overall weighted mean estimates were calculated for lesion size at presentation, growth rate and followup based upon combining single institutional series with complete information.

RESULTS

We identified 10 reports from 9 single institutional series in the world literature regarding the natural history of untreated solid localized renal lesions. The series included 6 to 40 patients (mean 25) with a mean followup of 30 months (range 25 to 39). When combined with our institutional data, a total of 286 lesions were analyzed, of which 234 could be included in the meta-analysis. Mean lesion size at presentation was 2.60 cm (median 2.48, range 1.73 to 4.08). Meta-analysis revealed a mean growth rate of 0.28 cm yearly (median 0.28, range 0.09 to 0.86) at a mean followup of 34 months (median 32, range 26 to 39) in all series combined. Pathological confirmation was available in 46% of the cases (131 of 286) and it confirmed 92% (120 of 131) as RCC variants. Evaluable data in this subset of confirmed RCC demonstrated a mean growth rate of 0.40 cm yearly (median 0.35, range 0.42 to 1.6). Lesion size at presentation did not predict the overall growth rate (p = 0.46). Progression to metastatic disease was identified in only 1% of lesions (3 of 286) during followup.

CONCLUSIONS

The majority of small enhancing renal masses grow at a slow rate when observed. Although metastatic and cancer specific death are low, serial radiographic data alone are insufficient to predict the true natural history of these lesions. Therefore, physicians and patients assume a calculated risk when following these tumors. Basic biological data are needed to assess the natural history of untreated renal masses.

Natural history of small renal cell carcinoma: evaluation of growth rate, histological grade, cell proliferation and apoptosis

PURPOSE

We investigated the natural history of incidentally discovered small renal cell carcinomas (RCCs), and we evaluated growth rate, apoptosis, cell proliferation and histological grade.

MATERIALS AND METHODS

A total of 18 patients with RCCs extirpated after at least 12 months of observation were reviewed retrospectively. The period of observation ranged from 12 to 63 months (median 22.5). Median patient age was 56.5 years, ranging from 37 to 71. Annual tumor growth rate was calculated from diameter obtained from computerized tomography or ultrasound. Cell proliferation and apoptosis were assessed by immunostaining using Ki-67 and TUNEL.

RESULTS

Average tumor growth rate was 0.42 cm per year (standard error 0.09, 95% confidence interval 0.24 to 0.61). Of the 18 tumors 7 were grade 1, 8 were grade 2 and 3 were grade 3. Tumor growth rate and Ki-67 positive ratio were not correlated. In contrast, growth rate and positive ratio of TUNEL were significantly correlated. A significant difference in growth rate was observed between grade 2 and 3 tumors but not between grade 1 and 2 tumors.

CONCLUSIONS

The growth rate of RCCs correlates with apoptosis and grade. Most incidentally found RCCs are slow growing. However, those with certain histopathological features can grow rapidly and have a poor prognosis. More attention should be given to the observation of small renal masses.

Surgery and angiogenesis

Surgery may be regarded as an angiogenesis-inducing condition since it evokes the release of many angiogenic factors. Regarding the mechanistic overlap between tumor-associated neovascularisation and (physiological) angiogenesis in response to injury and hypoxia, surgery may promote the uncontrolled growth of residual dormant tumor cells. With the advent of anti-angiogenic agents, surgeons will be faced with more patients undergoing surgery for primary and secondary tumors under anti-angiogenic treatment. This could present problems with regard to angiogenesis-dependent phenomena such as wound repair, healing of intestinal anastomoses and liver regeneration. In this review we will discuss these matters from a biomedical and clinical point of view.

Screening computed tomography: will it result in overdiagnosis of renal carcinoma?

BACKGROUND

Despite uncertain benefits and harms, screening computed tomography (CT) is being marketed to consumers in the U.S. One plausible harm is the detection and treatment of renal carcinoma cases that otherwise would have remained clinically silent during the patient's lifetime.

METHODS

After estimating the prevalence of preclinical renal carcinoma using meta-analysis of five series of asymptomatic, middle-aged Americans who received CT screening, the authors divided the prevalence by U.S. incidence rates of clinical renal carcinoma among persons of similar age. This calculation would estimate the mean duration of the detectable preclinical period (the "sojourn time") of renal carcinoma if the incidence of preclinical and clinical renal carcinoma were equivalent.

RESULTS

The 5 series included 16,174 screenees (mean age range, 58-64 years; 61% male). The prevalence of asymptomatic renal carcinoma ranged from 0.11% to 0.76%; the pooled prevalence was 0.21% (95% confidence interval, 0.14-0.28%). The estimated mean sojourn time for renal carcinoma was between 3.7 years and 5.8 years among middle-aged Americans.

CONCLUSIONS

Because most renal carcinomas grow slowly during the preclinical period, the authors' estimated mean sojourn time did not seem unduly long. Therefore, the incidence rate of clinical renal carcinoma most likely is a reasonable surrogate for the incidence rate of preclinical renal carcinoma, implying that most renal carcinomas detected by CT screening among middle-aged Americans are likely to progress to clinical diagnosis.

Efficiency of [(18)F]FDG PET in characterising renal cancer and detecting distant metastases: a comparison with CT

The purpose of this study was to assess the efficiency of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in the characterisation and primary staging of suspicious renal masses, in comparison with computed tomography, the current standard imaging modality. Fifty-three FDG PET studies were performed within the framework of a prospective study: 35 for both characterisation and staging of a suspicious mass, and 18 for staging early after surgical removal of a renal cancer. In the characterisation of renal masses, a high rate of false negative results was observed, leading to a sensitivity, specificity and accuracy of 47%, 80% and 51% respectively, versus 97%, 0/5 and 83% respectively for CT. FDG PET detected all the sites of distant metastasis revealed by CT, as well as eight additional metastatic sites, leading to an accuracy of 94% versus 89% for CT. However, 36/53 patients (68%) did not have any distant metastasis on either CT or on PET. All but one of these patients had a low Fuhrman histological grade and a limited local stage (< or =pT2). We conclude that FDG PET does not offer any advantage over CT for the characterisation of renal masses but that it appears to be an efficient tool for the detection of distant metastasis in renal cancer. However, our data suggest that a selection process could be implemented to determine which patients should undergo PET. FDG PET could be performed in the event of a solitary metastasis or doubtful images on CT. Selection could also be based on adverse histological findings from nephrectomy specimens in order to perform staging early after nephrectomy.

Cell proliferation, apoptosis, angiogenesis and growth rate of incidentally found renal cell carcinoma

BACKGROUND

Our previous study showed that the growth rate of incidentally found renal cell carcinoma (RCC) varied, and that the initial clinical and pathological features did not predict subsequent growth of the carcinoma. The objective of this study was to determine the relationships between cell proliferation, apoptosis, angiogenesis and the growth rates of these RCC.

METHODS

We examined cell proliferation, apoptosis, and angiogenesis in 16 incidentally found cases of RCC. Cell proliferation was assessed by immunohistochemical staining with a Ki-67 antibody. Apoptosis was assessed by the terminal deoxynucleotidyl transferase (TdT) mediated deoxy-UTP biotin nick end labeling (TUNEL) technique. The Ki-67 labeling index (KI) and the apoptotic index (AI) were determined as the ratio of immunohistochemically positive cells per 1000 cancer cells. The KI/AI ratio was also determined. Angiogenesis was evaluated by CD34 immunostaining. Finally, we investigated the correlation between these parameters and the growth rate of primary lesions of incidentally found RCC.

RESULTS

The KI ranged from 7 to 73 (median, 20), AI ranged from 6 to 171 (median, 26), and microvessel density (MVD) ranged from 21 to 673 (median, 265) for incidentally found RCC. Ki-67 labeling index, AI and MVD were not closely correlated to each other. Furthermore, these parameters were not associated with growth rates of incidentally found RCC. Only the KI/AI ratio was strongly correlated to the growth rate of incidentally found RCC (r = 0.709; P = 0.0083).

CONCLUSION

Our results suggest that the balance between cell proliferation and apoptosis partly determines the growth rate of primary lesions of incidentally found RCC.

Growth rates of primary and metastatic lesions of renal cell carcinoma

BACKGROUND

The natural history and growth rate of renal cell carcinoma (RCC) have not yet been determined. The growth rates of primary lesions in incidentally found RCC were compared with those of metastatic lesions.

METHODS

Sixteen patients who did not receive immediate surgical treatment for renal solid masses that were later proven to be RCC were reviewed retrospectively. All primary lesions of the 16 patients were found incidentally. For comparison, metastatic lesions were evaluated in another 16 patients with RCC. Of these, 11 underwent surgical treatment for the primary lesions.

RESULTS

The growth rates of primary and metastatic lesions of RCC varied. They ranged from 0.10 to 1.35 cm/year for primary lesions and from 0.08 to 7.87 cm/year for metastatic lesions. The growth rate of primary lesions of incidentally found RCC was lower than that of metastatic lesions (P = 0.0159). The initial tumor diameter and pathological grade did not affect the growth rate of the primary lesion of incidentally found RCC. However, a close correlation was found between the growth rate of metastatic lesions and the pathological grade of the primary lesion in patients with metastasis.

CONCLUSIONS

The growth rate of incidentally found RCC varied. Some patients with the disease may be candidates for 'watchful waiting' when an immediate surgical treatment is not indicated, but they should be selected with great caution.

Late pathologic changes in guinea pig kidneys irradiated with conventional fractionation and hyperfractionation

PURPOSE

The aim of this study was to determine the differences in renal damage particularly associated with the effect of a small dose per fraction with a constant total dose.

METHODS AND MATERIALS

Guinea pigs, 12-week-old English Hartley females, were used. The animals were divided into five groups according to irradiation schedule: No irradiation (control group); 2.0 Gy x 1/day, 5 fraction (f)/week (wk), 40 f, total 80 Gy (Group CF-2.0 [CF = conventional fractionation]); 1.0 Gy x 2/day, 10 f/wk, 80 f, total 80 Gy (Group HF-1.0 [HF = hyperfractionation]); 3.0 Gy x 1/day, 5 f/wk, 27 f, total 81 Gy (Group CF-3.0); and 1.5 Gy x 2/day, 10 f/wk, 54 f, total 81 Gy (Group HF-1.5). Only unilateral irradiation was performed. A histologic analysis was performed before irradiation and at 6 and 12 months after the completion of irradiation. The severity and severity ratios of urinary tubule atrophy, the number of large nuclei per unit area in the renal tubules, the average diameter of the glomeruli, and the number of cells composing the glomerulus were used as parameters for evaluating renal damage.

RESULTS

In Groups CF-2.0 and CF-3.0 (the conventional fractionation [CF] groups), all the renal tubules showed severe atrophy 12 months after irradiation. On the other hand, only 20% of the renal tubules showed slight atrophy in Group HF-1.0 at 12 months. In Group HF-1.5, 70% of the renal tubules were atrophic at 12 months. The number of large nuclei markedly increased in Groups HF-1.0 and HF-1.5 (the hyperfractionation [HF] groups) at 12 months, whereas the number was very low in the CF groups at 12 months. Only in Group HF-1.0 had the average diameter of glomeruli not shrunk at 12 months. The number of cells composing the glomerulus in the CF groups markedly decreased at 12 months. The number of cells in the HF groups was also reduced, however the reduction was not as severe as that observed in the CF groups.

CONCLUSION

1.0 Gy per fraction delivered by HF greatly reduces renal damage even in the 80 Gy-irradiated kidney, which is one of the most radiosensitive organs.

On the growth rates of human malignant tumors: implications for medical decision making

Testicular carcinomas, pediatric tumors, and some mesenchymal tumors are examples of rapidly proliferating cell populations, for which the tumor volume doubling time (TVDT) can be counted in days. Cancers from the breast, prostate, and colon are frequently slow-growing, displaying a TVDT of months or years. Irrespective of their growth rates, most human tumors have been found: to start from one single cell, to have a long subclinical period, to grow at constant rates for long periods of time, to start to metastasize often even before the primary is detected, and to have metastases that often grow at approximately the same rate as the primary tumor. The recognition of basic facts in tumor cell kinetics is essential in the evaluation of important present-day strategies in oncology. Among the facts emphasized in this review are: (1) Screening programs. Most tumors are several years old when detectable by present-day diagnostic methods. This makes the term "early detection" questionable. (2) Legal trials. The importance of so-called doctor's delay is often discussed, but the prognostic value of "early" detection is overestimated. (3) Analyses of clinical trials. Such analysis may be differentiated depending on the growth rates of the type of tumor studied. Furthermore, uncritical analysis of survival data may be misleading if the TVDT is not taken into consideration. (4) Analyses of epidemiological data. If causes of malignant tumors in humans are searched for, the time of exposure must be extended far back in the subject's history. (5) Risk estimations by insurance companies. For the majority of human cancers, the 5-year survival rate is not a valid measurement for cure. Thus, basic knowledge of tumor kinetics may have important implications for political health programs, legal trials, medical science, and insurance policies.