Abstract
The authors utilize the National Cancer Database to provide a 30,000-foot view of trends in the care of patients with T1a (<4 cm) renal masses between 1998 and 2012. Major deficiencies in this database that limit its value in this study include the following: overall survival (not cancer-specific, disease-free, or progression-free survival) is the only endpoint available, concurrent data on active surveillance is missing as is pretreatment kidney tumor biopsy data. Also missing is data on whether patients initially treated with ablation were retreated and how many times. In addition, assuming both partial nephrectomy and cryotherapy are being offered to treat kidney tumors, this database does not provide any tumor histopathologic data. Also, 51% of tumor grade data are missing in the cryoablation patients and 17% are missing in the partial nephrectomy patients. After propensity score matching, the authors report that the cryoablated patients were older, had significantly worse Charlson score, were less likely to be treated at an academic center, were less likely to be treated in the Northeast United States, were less likely to have private insurance, and were more likely to be in lower income levels. Overall survival was lower for cryoablated patients at 24, 48, and 96 months, a tendency that persisted even when a comparison analysis was done for young (<60 years) and healthy (Charlson 0) patients treated at academic centers. When tumors were >2 cm in diameter, overall survival was also significantly worse for patients treated with cyroablation compared with partial nephrectomy.
The combination of incidental tumor detection by modern imaging with the recent evolution of kidney sparing treatment options has brought many small renal mass patients to urology offices. Although at first glance one could argue that this large pool of asymptomatic patients, many of whom are elderly and have significant medical comorbidities, are suitable surgical or ablation treatment targets, most such small renal masses pose minimal if any near term oncologic risk. We now know that there are >30 different histologic subtypes of renal cortical tumors that can be broadly grouped into benign (20%), indolent with limited metastatic potential (25%), and malignant (clear cell, 54%). There is a wealth of population-based data describing the likely death of the elderly and comorbidly ill patients with a small renal mass from their competing illnesses and not kidney cancer, often within 3 years. Although guideline committees may say that a suitable patient for cryoablation is the elderly and comorbidly ill patient, it is this very patient who is best served with an active surveillance approach. This guideline-approved calculus may explain the poor overall survival results reported across the board in cryoablated patients. When the authors analyzed healthier and younger patients treated with cryoablation whose survival results were still inferior to partial nephrectomy, it may simply be that cryoablation is less effective than partial nephrectomy for a variety of technical reasons alluded to by the authors. Consideration for percutaneous renal mass biopsy in equivocal cases is always an option before committing to a formal intervention.
Today, often missing from the medical analytics, systematic reviews, outcome metrics, and guideline committees, coupled with the boon in medical technology, is the keen surgical judgment to properly select patients for surgical or interventional radiologic procedures with the goal of a meaningful extension of a patient's life. Because you can does not mean you should treat every patient with a small renal mass. Prevailing principles of oncology and medicine coupled with realistic treatment goals will reduce unnecessary and potentially deleterious procedures for patients not destined to benefit. Partial nephrectomy or cryoablation should not be offered to treat an anxious patient and family under the exaggerated impression that a small renal mass has immediate lethal capabilities or to enthusiastically utilize the new and expensive technologies heavily marketed now around the world.