Growth rates of primary and metastatic lesions 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.

Use of Circular RNAs in Diagnosis, Prognosis and Therapeutics of Renal Cell Carcinoma

Renal cell carcinoma is the most common type of kidney cancer, representing 90% of kidney cancer diagnoses, and the deadliest urological cancer. While the incidence and mortality rates by renal cell carcinoma are higher in men compared to women, in both sexes the clinical characteristics are the same, and usually unspecific, thereby hindering and delaying the diagnostic process and increasing the metastatic potential. Regarding treatment, surgical resection remains the main therapeutic strategy. However, even after radical nephrectomy, metastasis may still occur in some patients, with most metastatic renal cell carcinomas being resistant to chemotherapy and radiotherapy. Therefore, the identification of new biomarkers to help clinicians in the early detection, and treatment of renal cell carcinoma is essential. In this review, we describe circRNAs related to renal cell carcinoma processes reported to date and propose the use of some in therapeutic strategies for renal cell carcinoma treatment.

Natural history and growth kinetics of clear cell renal cell carcinoma in sporadic and von Hippel-Lindau disease

Background

To evaluate and compare the natural history and growth kinetics of sporadic clear cell renal cell carcinoma (ccRCC) with those of ccRCC in von Hippel-Lindau disease (VHL).

Methods

Sixty patients in the sporadic group with 61 tumors and 15 patients in the VHL group with 30 tumors whom all underwent delayed surgery after at least 12 months of active surveillance (AS) were enrolled to conduct a retrospective cohort study. The growth rate was calculated, and the growth kinetics between the sporadic and VHL groups were compared. The patient and tumor characteristics were reviewed, and their correlation with growth rate was analyzed.

Results

The mean growth rate of sporadic ccRCC was 0.91 cm/year (ranging from 0–4.74 cm/year) and that of VHL ccRCC was 0.47 cm/year (ranging from 0.04–1.89 cm/year). The growth rate of sporadic ccRCC showed a tendency of being faster than that of VHL ccRCC but did not reach statistical significance (P=0.07). The factors affecting the growth rate were different between the two groups. For VHL ccRCC, the only factor that correlated with growth rate was initial tumor diameter (P<0.001), but for sporadic ccRCC, the only factor was pathological nuclear grade (P<0.001).

Conclusions

The growth rate of VHL-associated ccRCC might be slower than that of sporadic ccRCC. Furthermore, we identified a disparity in growth kinetics between sporadic and VHL-associated ccRCC.

Renal tumor growth rate in patients with previously normal CT scan: Analysis of the initial stage of growth

OBJECTIVE

Most of the studies regarding natural history of renal masses are based on active surveillance series and suggest that the renal masses have a slow growth rate. Nevertheless, only a few studies report the time between a normal computed tomography (CT) scan to the first detection of a tumor. We aimed to analyze the growth rate in newly diagnosed kidney tumors.

MATERIAL AND METHODS

We analyzed patients with enhancing renal masses that developed after a normal CT scan, which was performed at most 12 months earlier. Variables examined included patient age, gender, tumor size, volume, tumor linear growth rate (LGR). All cases were surgically treated. Mann-Whitney U test was used to compare variables. A p<0.05 was considered as statistically significant.

RESULTS

We found 31 patients with 33 lesions. Male to female ratio was 1.58 (19/12). The average age was 59.2 years (standard deviation [SD]±12.1), and the mean tumor size was 4.27 cm (SD±4.3). Tumor LGR was 0.87 cm/month (range: 0.28-1.66) and presumed to be 10.4 cm at 1 year (range: 3.36-19.9). Tumor LGR for time detection at <6 month or ≥6 months were 1.1 cm/month and 0.68 cm/month (range: 0.27-1.08 and 0.88-1.76, respectively; p=0.0004), respectively. Tumor LGRs for low- and high-grade tumors were 0.89 cm/month and 0.83 cm/month (p=0.65), respectively. Median volume was 36.1 cm³ (range: 2.61-143.7), and for low and high grade the median volumes were 27.9 cm³ and 47.6 cm³, respectively (p=0.54). Malignant pathology was present in 93.9 % (31 of 33) of masses (lesions).

CONCLUSION

We found differences in tumor LGR in tumors detected before and after 6 months. We did not find any correlation between tumor growth rate and Fuhrman grade system, gender, histology, or age. We found the highest LGR published up to date.

Disease progression model of 4T1 metastatic breast cancer

Cancer metastasis is the main cause of death in various types of cancer. However, in the field of pharmacometrics, cancer disease progression models focus on the growth of primary tumors with tumor volume or weight as target values, while the metastasis process is less mentioned. We propose a series of mathematical models to quantitatively describe and predict the disease progression of 4T1 breast cancer in the aspect of primary breast tumor, lung metastasis and white blood cell. The 4T1 cells were injected into breast fat pad of female BALB/c mice to establish an animal model of breast cancer metastasis. The number and volume of lung metastases at different times were measured. Based on the above data, a disease progression model of breast cancer lung metastasis was established and parameter values were estimated. The white blood cell growth and the primary tumor growth of 4T1 mouse are also modeled. The established models can describe the lung metastasis of 4T1 breast cancer in three aspects: (1) the increase in metastasis number; (2) the growth of metastasis volume; (3) metastasis number-size distribution at different time points. Compared with the prior metastasis models based on von Forester equation, our models distinguished the growth rate of primary tumor and metastasis and got parameter values for 4T1 mouse model. And the current models optimized the metastasis number-size distribution model by utilizing logistic function instead of the prior power function. This study provides a comprehensive description of lung metastasis progression for 4T1 breast cancer model, as well as an alternative disease progression model structure for further pharmacodynamics modeling.

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.

Kidney ultrasound - what is important for a urologist?

Kidney ultrasound is one of the basic procedures in the practice of a urologist. Apart from the location and the size, description of renal morphology should contain the thickness of the anterior lip parenchyma in a transverse section and the location of possible narrowings. Uneven outline of the kidney is a sign of past inflammatory conditions. In the case of the pelvicalyceal system dilation, it is advised to specify the dimensions of the pelvis and calyces. Convex shape of the calyces proves elevated pressure within the pelvicalyceal system. Hydronephrosis is present when urinary retention has led to thinning the renal parenchyma. In each case, one should identify the reason for urinary retention in the upper urinary tract. Urinary retention on both sides requires one to exclude urinary bladder tumor, it may also be caused by a benign prostatic hyperplasia. Ultrasound examination is a sensitive method of renal stones detection, regardless of their chemical composition. Cyst description in an ultrasound image should cover its morphological features, differentiating between the so-called simple or complex cysts. In the case of a solid lesion, ultrasound makes it possible to detect parenchymal lesions usually starting with the size of 2–2.5 cm. It enables one to particularly diagnose angiomyolipomas. As regards the remaining parenchymal lesions, differentiation of the lesion nature is impossible. In some cases of angiomyolipoma, when it contains bleeding areas present and when it is deficient in adipose tissue, it resembles adenocarcinoma. It is necessary that the description includes the exact location, especially the dimensions and relation of the tumor to the renal sinus. In the case of larger lesions, respiratory motion of the kidney, the condition of the adrenal gland and the presence of enlarged lymph nodes should be controlled. Additionally, one should evaluate the renal vein and inferior vena cava in terms of a neoplastic plug presence.

Natural and Clinical Course of Renal Cell Carcinoma — Better Prospect for the Patients

The many improvements in diagnostic and therapeutic tools over the last half-century have changed the prospects for patients with renal cell carcinoma (RCC). Higher survival rates and less morbidity have been achieved. The disease is, however, still unpredictable and represents many unsolved problems.

In this paper we focus on determinants of the natural and clinical course of RCC and the changes in regard to this over the last decades.

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.

Early and multiple origins of metastatic lineages within primary tumors

Many aspects of the evolutionary process of tumorigenesis that are fundamental to cancer biology and targeted treatment have been challenging to reveal, such as the divergence times and genetic clonality of metastatic lineages. To address these challenges, we performed tumor phylogenetics using molecular evolutionary models, reconstructed ancestral states of somatic mutations, and inferred cancer chronograms to yield three conclusions. First, in contrast to a linear model of cancer progression, metastases can originate from divergent lineages within primary tumors. Evolved genetic changes in cancer lineages likely affect only the proclivity toward metastasis. Single genetic changes are unlikely to be necessary or sufficient for metastasis. Second, metastatic lineages can arise early in tumor development, sometimes long before diagnosis. The early genetic divergence of some metastatic lineages directs attention toward research on driver genes that are mutated early in cancer evolution. Last, the temporal order of occurrence of driver mutations can be inferred from phylogenetic analysis of cancer chronograms, guiding development of targeted therapeutics effective against primary tumors and metastases.

Comparison of Renal Cell Carcinoma Surveillance Guidelines: Competing Trade-Offs

PURPOSE

We estimated the differences in intensity, cost, radiation exposure and cancer control of published surveillance guidelines screening for secondary renal cell carcinoma in patients treated with partial nephrectomy.

MATERIALS AND METHODS

We developed a Monte Carlo simulation model to contrast the existing guidelines in terms of cost, radiation exposure and cancer control. Model inputs were extrapolated from the existing literature. Surveillance guidelines were analyzed from the AUA, CUA, EAU and NCCN®. Risk stratification among patients treated with partial nephrectomy was based on tumor characteristics.

RESULTS

Expected costs during the 5 years after partial nephrectomy were $587 (CUA), $1,076 (AUA), $1,705 (EAU) and $1,768 (NCCN) for low risk patients, and $903 (CUA), $2,525 (EAU) and $3,904 (AUA and NCCN) for high risk patients. Radiation exposure ranged from 31.41 mSv (CUA) to 104.34 mSv (NCCN) for low risk patients and 46.88 mSv (CUA) to 231.61 mSv (AUA and NCCN) for high risk patients. The EAU and CUA guidelines led to the diagnosis of the highest percentage of low risk patients (more than 95%) while all guidelines diagnosed more than 92% of high risk patients with recurrence.

CONCLUSIONS

Renal cell carcinoma surveillance guidelines differ greatly in terms of intensity, cost and radiation exposure. It is important for clinicians to adopt standardized surveillance strategies that limit unnecessary cost and radiation exposure without compromising cancer control.

The growth rate of "clinically significant" renal cancer

Surveillance studies of enhancing renal masses report on a mean tumor growth rate of about 0.3 cm/year. In most of these studies however, only small tumors in elderly patients were followed. In the current report, we attempt to evaluate the growth rate of “clinically significant” renal carcinomas defined as tumors that were treated immediately upon diagnosis. 46 patients (mean age 64 years SD 11 years) were treated for renal carcinoma. All had a cross-sectional imaging studies performed 6–60 months prior to diagnosis of kidney cancer demonstrating no tumor. Tumor growth rate was calculated by dividing tumor’s largest diameter by the time interval between the normal kidney imaging and diagnosis of renal cancer. Mean tumor diameter was 4.5 cm (SD 2.4 cm). Mean time period from the normal imaging to diagnosis of renal cancer was 33.6 months (SD 18 months). According to the proposed model, the average growth rate of “clinically significant” renal carcinomas was 2.13 cm/year (SD 1.45, range 0.2–6.5 cm/year). Tumor growth rate correlated inversely with patient’s age (p = 0.007). Patient gender or Fuhrman’s grade did not correlate however. The growth rate of “clinically significant” renal cancer appears to be higher than the rate reported in surveillance trials. Renal tumors tend to grow faster in young patients. As such, variable growth rate should be taken into account when considering active surveillance in young patients and when designing trials for evaluation of anti-cancer agents.

Active surveillance for metastatic or recurrent renal cell carcinoma

PURPOSE

Metastatic renal cell carcinoma (mRCC) sometimes presents with an indolent course without any significant symptoms. Here, the potential impact of active surveillance (AS) on clinical outcomes in asymptomatic or minimally symptomatic mRCC patients was retrospectively evaluated.

METHODS

mRCC patients who were followed up with deferred treatment for the purpose of AS between 2000 and 2012 were enrolled. Patient and disease characteristics, outcomes of AS and subsequent therapies, and predictive factors for rapid disease progression were analyzed. The primary endpoint was time-to-progression (TTP).

RESULTS

First-line systemic therapy was deliberately deferred in 58 patients. During AS, the best overall responses were stable disease for 48 patients (83 %) and progressive disease (PD) for 10 patients (17 %), and 47 patients ultimately experienced disease progression at the time of data cutoff. With a median follow-up of 31.4 months, the median TTP was 12.4 months (95 % confidence interval 8.4-16.5) and median overall survival was not reached. After univariate and multivariate analyses for TTP, Karnofsky performance status <100 %, liver metastasis, and a time from diagnosis to AS of less than 1 year were found to be predictive factors for a shorter TTP. After PD, 30 patients received systemic treatment (14 sunitinib, 11 pazopanib, 4 immunotherapy, and 1 temsirolimus). The objective response rates were 71 % for sunitinib and 46 % for pazopanib, which were deemed comparable with historical controls.

CONCLUSIONS

Asymptomatic or minimally symptomatic mRCC patients can be observed for a prolonged period of time without active treatment.

Tumor doubling time of renal cell carcinoma measured by CT

Introduction:

Increasing numbers of patients are now being incidentally detected with small-sized renal cell carcinoma (RCC). The natural history of small renal masses is not completely understood. Currently, there are no specific tumor markers to determine initial risk or progression to metastatic disease. Growth rate and tumor size are factors shown to be predictive of tumor biology. In this study, we attempted to examine the natural history of RCC and calculated the doubling times (DTs) of untreated RCC at the primary site.

Materials and Methods:

We retrospectively reviewed the records of all patients with RCC who had at least two measurements of the same tumor mass obtained on computed tomography (CT) imaging on two different dates (at least 6 months apart) during periods of non-treatment. The tumor volume was calculated at two points in time using images yielded by the CT imaging. The tumor DT was calculated using the following equation: DT = (T – T0) × log2/logV – logV0.

Results:

Twenty-two (13 male and nine female) patients with ages ranging from 32 to 71 years (mean 52.22 years) were included in the study. The initial maximum tumor diameter ranged from 2.8 to 6.8 cm (mean 3.93 cm) and the last maximum tumor diameter ranged from 3.2 to 7.8 cm (mean 4.39 cm). The DT for the entire population was 460.01 days (range 174-913 days).

Conclusions:

RCC is a diverse disease process, with the majority of lesions demonstrating malignant disorder. In our study, the DT for the patient population was 460.01 days (range 174-913 days).

Percutaneous radiofrequency ablation: minimally invasive therapy for renal tumors

Currently, up to 60% of renal tumors are detected incidentally by abdominal imaging. Most of these tumors are small and localized to the kidney. Owing to the shift to lower stage at diagnosis, radical nephrectomy has fallen out of favor and has been replaced by nephron-sparing surgery. Currently, partial nephrectomy is the treatment of choice for patients with small renal tumors. As the trend towards less invasive therapy continues, laparoscopic and percutaneous ablation techniques have gained popularity for the treatment of renal tumors in patients who are high-risk surgical candidates, or have a solitary kidney, limited renal function or multifocal disease. Percutaneous radiofrequency ablation is a safe, minimally invasive treatment option for those patients.

Factors affecting survival in 267 consecutive patients undergoing surgery for spinal metastasis from renal cell carcinoma

OBJECT

Renal cell carcinoma (RCC) frequently metastasizes to the spine, and the prognosis can be quite variable. Surgical removal of the tumor with spinal reconstruction has been a mainstay of palliative treatment. The ability to predict prognosis is valuable when determining the role and magnitude of surgical intervention in cancer patients. To better identify factors affecting survival in patients undergoing surgery for spinal metastasis from RCC, the authors undertook a retrospective analysis of a large patient cohort at a tertiary care cancer center.

METHODS

Relevant clinical data on a consecutive series of patients who had undergone surgery for spinal metastasis of RCC between 1993 and 2007 at The University of Texas MD Anderson Cancer Center were retrospectively reviewed. Demographic data, histopathological grade of primary tumor, timing of spinal surgery relative to diagnosis, treatment history prior to surgery, neurological status, and systemic disease burden were analyzed to determine the impact of these factors on survival outcome.

RESULTS

The authors identified 267 patients who met the study criteria. Five-year overall survival (OS) after spine tumor resection was 7.8%, with a median OS of 11.3 months (95% CI 9.5-13.0 months). Patients with Fuhrman Grade 4 RCC had a median OS of 6.1 months (95% CI 3.5-8.7 months), which was significantly lower than the 14.3 months (95% CI 9.1-19.4 months) observed in patients with Fuhrman Grade 3 or less RCC (p < 0.001). Patients with preoperative neurological deficits had a median survival of 5.9 months (95% CI 4.1-7.7 months), which was significantly lower than the 13.5 months (95% CI 10.4-16.6 months) observed in patients with a normal neurological examination (p < 0.001). Patients whose spine was the only site of metastasis had a median OS of 19 months (95% CI 9.8-28.2 months) after surgery, significantly longer than the 9.7 months (95% CI 8.1-11.3 months) observed in patients with additional extraspinal metastasis sites (p < 0.001). Patients with nonprogressing extraspinal metastasis (no metastasis, stable, or concurrent) had a median survival of 20.6 months (95% CI 15.1-26.1 months), compared with 5.6 months (95% CI 4.4-6.8 months) in patients with progressing metastasis (p < 0.001).

CONCLUSIONS

The authors identified several factors influencing survival after spine surgery for metastatic spinal RCC, including grade of the original nephrectomy specimen, activity of the systemic disease, and neurological status at the time of surgery. These clinical features may help to identify patients who may benefit from aggressive surgical intervention.

Detection of intratumoral susceptibility signals using T2*-weighted gradient echo MRI in patients with clear cell renal cell carcinoma

Objective

To retrospectively evaluate whether T2*-weighted imaging can be used to grade clear cell renal cell carcinomas (ccRCC) based on intratumoral susceptibility signals (ISSs).

Materials and Methods

MR imaging from 37 patients with pathologically-proven ccRCCs was evaluated. ISSs on T2*WI were classified as linear or conglomerated linear structures (type I) and dot-like or patchy foci (type II). Two radiologists assessed the likelihood of the presence of ISS, dominant structure of ISS and ratio of ISS area to tumor area. Results were analyzed by nonparametric Mann-Whitney test.

Results

ISSs were seen in all patients except for four patients with low-grade ccRCCs and two patients with high-grade ccRCCs. There was no significant difference of the likelihood of the presence of ISS between low- and high-grade ccRCCs. More type I ISSs and less type II ISSs were predictive of low-grade tumors, whereas more conspicuity type II ISSs correlated with higher occurrence of high-grade tumors (P<0.05). The ratio of ISS area to tumor area was also significantly higher for the high-grade group (1.27±0.79) than that for the low-grade group (0.81±0.40) (P<0.05).

Conclusion

ISSs on T2*-weighted gradient-echo MR images can help grade ccRCCs before operations.

Plasminogen activator inhibitor-1 inhibitors: a patent review (2006-present)

INTRODUCTION

Plasminogen activator inhibitor-1 (PAI-1), the serine protease inhibitor (serpin), binds to and inhibits the plasminogen activators-tissue-type plasminogen activator (tPA) and the urokinase-type plasminogen activator (uPA). This results in both a decrease in plasmin production and a decrease in the dissolution of fibrin clots. Elevated levels of PAI-1 are correlated with an increased risk for cardiovascular disease and have been linked to obesity and metabolic syndrome. Consequently, the pharmacological suppression of PAI-1 might prevent or treat vascular disease.

AREAS COVERED

This article provides an overview of the patenting activity on PAI-1 inhibitors. Patents filed by pharmaceutical companies or individual research groups are described, and the biological and biochemical evaluation of the inhibitors, including in vitro and in vivo studies, is discussed. An overview of patents pertaining to using these inhibitors for treating various diseases is also included.

EXPERT OPINION

Although there is still no PAI-1 inhibitor being evaluated in a clinical setting or approved for human therapy, research in this field has progressed, and promising new compounds have been designed. Most research has focused on improving the pharmacological profile of these compounds, which will hopefully allow them to proceed to clinical studies. Despite the need for further testing and research, the potential use of PAI-1 inhibitors for treating cardiovascular disease appears quite promising.

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.

Are multiple cryoprobes additive or synergistic in renal cryotherapy?

OBJECTIVE

To investigate the relationship between multiple cryoprobes was investigated to determine whether they work in an additive or synergistic fashion in an in vivo animal model because 1.47 mm (17-gauge) cryoprobes have been introduced to the armamentarium for renal cryotherapy.

METHODS

Laparoscopic-guided percutaneous cryoablation was performed in both renal poles of 3 pigs using 3 IceRod cryoprobes. These 12 cryolesions were compared with 12 cryolesions using a single IceRod cryoprobe. Each cycle consisted of two 10-minute freeze cycles separated by a 5-minute thaw. The iceball volume was measured using intraoperative ultrasonography. The kidneys were harvested, and cryolesion surface area was calculated. The lesions were fixed and excised to obtain a volume measurement. Statistical analysis was used to compare the single probe results multiplied by 3 to the multiple probe group for iceball volume, cryolesion surface area, and cryolesion volume.

RESULTS

The iceball volume for the first freeze cycle for the single cryoprobe multiplied by 3 was 8.55 cm3 compared with 9.79 cm3 for the multiple cryoprobe group (P=.44) and 10.01 cm3 versus 16.58 cm3 for the second freeze (P=.03). The cryolesion volume for the single cryoprobe multiplied by 3 was 11.29 cm3 versus 14.75 cm3 for the multiple cyroprobe group (P=.06). The gross cryolesion surface area for the single cryoprobe multiplied by 3 was 13.14 cm2 versus 13.89 cm2 for the multiple probe group (P=.52).

CONCLUSION

The cryolesion created by 3 simultaneously activated 1.47-mm probes appears to be larger than that of an additive effect. The lesions were significantly larger as measured by ultrasonography and nearly so (P=.06) as measured by the gross cryolesion volume.

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.

Optimal freeze cycle length for renal cryotherapy

PURPOSE

To our knowledge the optimal freeze cycle length in renal cryotherapy is unknown. Ten-minute time based freeze cycles were compared to temperature based freeze cycles to -20C.

MATERIALS AND METHODS

Laparoscopic renal cryotherapy was performed on 16 swine. Time based trials consisted of a double 10-minute freeze separated by a 5-minute thaw. Temperature based trials were double cycles of 1, 5 or 10-minute freeze initiated after 1 of 4 sensors indicated -20C. A 5-minute active thaw was used between freeze cycles. Control trials consisted of cryoneedle placement for 25 minutes without freeze or thaw. Viability staining and histological analysis were done.

RESULTS

There was no difference in cellular necrosis between any of the temperature based freeze cycles (p = 0.1). Time based freeze cycles showed more nuclear pyknosis, indicative of necrosis, than the 3 experimental freeze cycles for the renal cortex (p = 0.05) but not for the renal medulla (p = 0.61). Mean time to -20C for freeze cycle 1 was 19 minutes 10 seconds (range 9 to 46 minutes). In 4 of 21 trials (19%) -20C was never attained despite freezing for 25 to 63 minutes.

CONCLUSIONS

There was no difference in immediate cellular necrosis among double 1, 5 or 10-minute freeze cycles. Cellular necrosis was evident on histological analysis for trials in which -20C was attained and in freeze cycles based on time alone. With a standard 10-minute cryoablation period most treated parenchyma 1 cm from the probe never attained -20C. Cell death appeared to occur at temperatures warmer than -20C during renal cryotherapy.

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.

Minimally invasive treatment of small renal tumors: trends in renal cancer diagnosis and management

Renal cell carcinoma is a common malignancy causing significant mortality. In recent years abdominal imaging, often for alternate symptomatology, has led the trend toward the detection and confirmation of smaller renal tumors. This has permitted the greater use of localized and nephron-sparing techniques including partial nephrectomy and image-guided ablation. This article aims to review the current role of image-guided biopsy and ablation in the management of small renal tumors. The natural history of renal cell carcinoma, the role of renal biopsy, the principles and procedural considerations of thermal energy ablation, and the oncological outcomes of these minimally invasive treatments are discussed and illustrated with cases from the authors' institution. Image-guided ablation, in particular, has changed the treatment paradigm and, by virtue of its increasingly evident efficacy and low morbidity, now favors the treatment of smaller tumors in patients previously unfit for surgery.

Imaging and management of the incidentally discovered renal mass

Improvements in imaging technology and the expanding use of imaging have led to a rapid increase in the discovery of incidental renal lesions. These can present both the radiologist and the referring clinician with diagnostic dilemmas. This article addresses the most frequently encountered lesions and provides a framework for the diagnostic and management pathways for both solid and cystic lesions.

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.

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.

Histological characterisation of small renal masses and incidence of silent renal masses

With the introduction of sonographic and CT examinations, the number of small renal masses detected has increased. Benign neoplastic lesions are usually smaller than 4 cm in size, whilst the most common types of renal cell carcinomas have a mean size greater than that, but we must not forget that a significant number of small masses are renal cell carcinomas; even though the rate of benign cases increases as the diameter of the lesions decreases, therefore, size itself cannot be used to rule out a diagnostic of malignancy and often image characteristics are not enough to predict the nature of the lesion with certainty. In this case, histological confirmation must be recommended. Ideally, the histological study must be conducted on the surgical specimen, even though biopsy can be an option in selected cases.

Surveillance for the management of small renal masses

Surveillance is a new management option for small renal masses (SRMs) in aged and infirm patients with short-life expectancy. The current literature on surveillance of SRM contains mostly small, retrospective studies with limited data. Imaging alone is inadequate for suggesting the aggressive potential of SRM for both diagnosis and followup. Current data suggest that a computed tomography (CT) or magnetic resonance imaging (MRI) every 3 months in the 1st year, every 6 months in the next 2 years, and every year thereafter, is appropriate for observation. The authors rather believe in active surveillance with mandatory initial and followup renal tumor biopsies than classical observation. Since not all SRMs are harmless, selection criteria for active surveillance need to be improved. In addition, there is need for larger studies in order to better outline oncological outcome and followup protocols.

Watchful waiting for small renal masses

Small renal masses (SRMs; < 4 cm in diameter) account for most renal tumors treated today. Incidental early detection of SRMs by abdominal imaging results in favorable grade and stage migration to renal cell carcinoma, and also increases detection of benign renal tumors. As a result, most SRMs manifest indolent biological behavior with excellent prognosis. Despite the increased use of minimally invasive laparoscopic surgery, nephron-sparing techniques, and percutaneous ablation therapy, selected patients are managed by initial active surveillance, reserving therapy for progression. Older patients and those with competing risks due to medical comorbidities are excellent candidates for active surveillance; their risk of early progression due to growth or metastases appears to be low. Active surveillance should not be recommended for younger, healthier patients until prognostic factors are better defined. Needle core use for improved histopathologic characterization of SRMs should be considered before recommending treatment.

Serum amyloid A as indicator of distant metastases but not as early tumor marker in patients with renal cell carcinoma

The aim of the present study was to evaluate the clinical significance of the concentration of serum amyloid A (SAA) in patients with renal cell carcinoma (RCC). SAA protein was determined with enzyme-linked immunosorbent assay in serum samples of 55 healthy controls and 98 RCC patients subdivided into groups with localized tumor (N0M0, n=40), with lymph node metastases (N1M0, n=13), and distant metastases (M1, n=45). SAA concentrations in controls and N0M0 group of RCC were not different while SAA concentrations were significantly elevated in M1 patients compared to the N1M0 and N0M0 patients. In this respect, SAA provided an accurate detection of distant metastases with the area under the ROC curve of 0.86. SAA was identified as a significant independent factor of survival in RCC patients using the multivariate Cox proportional hazards regression model. SAA could be a useful analyte in predicting the survival outcome of RCC patients.

[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.

Volume doubling time and growth rate of renal cell carcinoma determined by helical CT: a single-institution experience

The purpose of this study was to retrospectively evaluate the volume doubling time (VDT) and growth rate of renal cell carcinomas (RCC) on a serial computed tomography (CT) scan. Thirty pathologically proven RCCs were reviewed with helical CT. Each tumor underwent at least two CT scans. Tumor volume was determined using an area measuring tool and the summation-of-areas technique. Growth rate was evaluated in terms of diameter and volume changes. VDT and volume growth rate were compared in relation to several factors (initial diameter, initial volume, diameter growth rate, volume growth rate, tumor grade, tumor subtype, sex or age). Mean VDT of RCCs was 505 days. Mean diameter and volume growth rate were 0.59 cm/year and 19.1 cm(3)/year, respectively. For volume and diameter growth rate, tumors < or =4 cm showed lower rates than those >4 cm (P < 0.01). VDT was weakly negatively correlated with diameter growth rate (P > 0.05). Volume growth rate was moderately to strongly positively correlated with initial diameter, initial volume and diameter growth rate (P < 0.05). In conclusion, small RCCs grew at a slow rate both diametrically and volumetrically. More accurate assessment of tumor growth rate and VDT may be helpful to understand the natural history of RCC.

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.