Limitations of preoperative biopsy in patients with metastatic renal cell carcinoma: comparison to surgical pathology in 405 cases

Study Type – Diagnostic (cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Although there have been many investigations of biopsy for small renal masses, there are scant data on the accuracy of biopsy in the setting of metastatic renal cell carcinoma (mRCC). We report a large series of biopsies and compare with nephrectomy pathology in patients with mRCC. The present study highlights the inaccuracy of biopsy in the setting of metastatic disease, which is related to sampling error because of heterogeneity within the tumour and among metastases. These limitations are important to realize when designing trials that depend on pathological findings from biopsy and not nephrectomy. In addition, we found that biopsy of primary tumours were more likely than biopsy of metastatic sites to be diagnostic of RCC. Future studies with multiquadrant biopsies of primary tumours could yield the most accurate pathological results for future studies.

OBJECTIVE

• ? To evaluate the ability of preoperative biopsy to identify high‐risk pathological features by comparing pathology from preoperative metastatic site and primary tumour biopsies with nephrectomy pathology in patients with metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

• ? We reviewed clinical and pathological data from patients who underwent biopsy before cytoreductive nephrectomy for mRCC at MD Anderson Cancer Center (MDACC) from 1991 to 2007.
• ? Percutaneous biopsy techniques included fine‐needle aspiration, core needle biopsy or a combination of both techniques.

RESULTS

• ? The pathology of 405 preoperative biopsies (239 metastatic site, 166 primary tumour) from 378 patients was reviewed at MDACC before cytoreductive nephrectomy.
• ? The biopsy and nephrectomy specimens had the same histological subtype in 96.0% of clear‐cell renal cell carcinomas (RCCs) and 72.7% of non‐clear‐cell RCCs.
• ? Of 76 nephrectomy specimens where sarcomatoid de‐differentiation was identified, only seven (9.2%) were able to be identified from the preoperative biopsy.
• ? In 38.3% of patients, the same Fuhrman grade was identified in both the biopsy and nephrectomy specimens.
• ? A definitive diagnosis of RCC was more likely to be reported in primary tumour biopsies than in metastatic site biopsies. (P < 0.001).

CONCLUSIONS

• ? Preoperative biopsy has limited ability to identify non‐clear‐cell histological subtype, Fuhrman grade or sarcomatoid features.
• ? When surgical pathology is not available, a biopsy obtaining multiple samples from different sites within the primary tumour should be recommended rather than limited metastatic site biopsy to identify patients for clinical trials.