Page 3 - Role of renal mass biopsy in the management of kidney cancer: KCRNC

Consensus: Renal mass biopsy

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Centers with an experienced radiologist to perform renal biopsies (https://thrombosiscanada.ca/guides/). Additional
mass biopsies and a genitourinary pathologist to review the guidance for management of anticoagulation and antiplate-
tissue have reported consistently high diagnostic rates. 5,7,25,26 lets around the time of renal mass biopsy can also be found
It is not known if these results can be replicated in lower- in the Canadian Urological Association (CUA) guideline on
volume centers. Systematic reviews have shown variabil- perioperative thromboprophylaxis. 32
ity in diagnostic accuracy of renal mass biopsy does exist
between centers, therefore, individual centers are encour- Predictive tools for patient with renal masses
aged to review their institutional experience when pos -
sible. 7,27 Patient factors and mass characteristics may alter The risk that a renal mass is malignant is associated with
the difficulty and decrease the accuracy of renal mass biop- patient factors and mass characteristics. A number of clinical
sy. Smaller mass diameter, cystic components, and longer tools have been created to assist physicians and patients in the
skin-to-mass distance reduce the diagnostic yield of a renal decision-making process by attempting to predict the chance
mass biopsy. 5,28 a renal mass is malignant. Nomograms require the input of
patient and mass characteristics and can provide a percentage
Safety of renal mass biopsy chance that a mass is cancerous. 8,33 One available nomogram
uses patient demographic factors and the R.E.N.A.L nephrom-
4. Renal mass biopsy is safe, with low rates of complica- etry score to predict whether a mass was benign or malignant,
33
tions when performed at experienced centers in prop- as well as if it was high-grade or low-grade. This nomogram
erly selected patients. Patients should be informed of was able to predict malignancy (area under the curve [AUC]
the risk of complications. 0.76) and the grade of the mass (AUC 0.73) with good accur-
33
The benefit-to-risk ratio of a diagnostic test should be acy but has not been externally validated. Classification trees
considered prior to ordering the test. This is especially true have also been created to guide physician decision-making
for invasive tests, including renal mass biopsy. The over- when assessing a patient with a small renal mass. These clin-
all risk of complications following renal mass biopsy in ical tools are based on patient factors and mass characteris-
published series is 8%, with the majority of these being tics and are meant to follow a physician’s thought process.
Clavien 1 complications. The most common risk of renal Recently, a Canadian-based classification tree for small renal
7
mass biopsy is bleeding, which is usually minor and lim- masses was externally validated and updated, with an accur-
7
ited to a self-resolving perirenal hematoma (4.3%). Mild acy of 87% (95% confidence interval 0.84‒0.89) at predicting
hematuria and back pain are reported in 3.2% and 3% of for malignant pathology on renal mass biopsy. 34
7
patients, respectively. Significant bleeding requiring blood Use of predictive tools to determine an individual patient’s
7
transfusion was reported in 0.7% of patients. Clavien ≥2 pre-test probability of a malignant mass (in this case pre-renal
complications are uncommon (<0.5%) in reported series. 7 mass biopsy) contributes to personalized care, and may assist
The risk of complications varies by center, patient, and in determining if a biopsy is required. Despite the availability
mass characteristics, and these should be considered when of these predictive tools, the ability to differentiate between
counselling patients. high-grade and low-grade histology using currently available
Tumor seeding of the biopsy tract may be a concern when tools is limited, and care must be taken when using a pre-
a malignant mass is sampled. Very few cases of tumor seed- dictive tool to determine if a biopsy should be performed. 35
ing along the biopsy tract after renal mass biopsy have been
reported in contemporary series. 7,12 One recent case series Renal mass biopsy for small renal masses
from a referral center in the U.K. reported evidence of RCC
along the biopsy tract of seven patients based on examina- 5. Renal mass biopsy should routinely be discussed with
29
tion of the surgical specimen. Tumor seeding following patients with a small renal mass prior to management.
renal mass biopsy causing clinical manifestations is currently 6. Shared decision-making should be used to determine
felt to be a low risk to patients. if renal mass biopsy will be performed. Patients should
Anticoagulation and antiplatelet medications should be informed of the possible benefits and harms, what is
be stopped if safe to do so prior to renal mass biopsy to known about the diagnostic accuracy of the biopsy, and
reduce the risk of bleeding complications. For high-risk how the biopsy should be interpreted. Patients’ values
30
patients (e.g., recent coronary artery stenting, recent venous and preferences should be elicited. Most importantly, it
thromboembolism, high CHADS score) consultation with should be determined whether the results of the biopsy
a thrombosis expert is recommended. Thrombosis Canada will influence management.
has a useful online tool to aid physicians when determin- 7. Patients who have a non-diagnostic renal mass biopsy
ing the optimal timing to stop and restart anticoagulants for a small renal mass should be counselled on the
and antiplatelets around procedures, including renal mass benefits and harms of a repeat biopsy.

CUAJ • December 2019 • Volume 13, Issue 12 379