The importance of surgical margins in renal cell and urothelial carcinomas

Distinguishing Renal Cell Carcinoma From Normal Kidney Tissue Using Mass Spectrometry Imaging Combined With Machine Learning

PURPOSE

Accurately distinguishing renal cell carcinoma (RCC) from normal kidney tissue is critical for identifying positive surgical margins (PSMs) during partial and radical nephrectomy, which remains the primary intervention for localized RCC. Techniques that detect PSM with higher accuracy and faster turnaround time than intraoperative frozen section (IFS) analysis can help decrease reoperation rates, relieve patient anxiety and costs, and potentially improve patient outcomes.

MATERIALS AND METHODS

Here, we extended our combined desorption electrospray ionization mass spectrometry imaging (DESI-MSI) and machine learning methodology to identify metabolite and lipid species from tissue surfaces that can distinguish normal tissues from clear cell RCC (ccRCC), papillary RCC (pRCC), and chromophobe RCC (chRCC) tissues.

RESULTS

From 24 normal and 40 renal cancer (23 ccRCC, 13 pRCC, and 4 chRCC) tissues, we developed a multinomial lasso classifier that selects 281 total analytes from over 27,000 detected molecular species that distinguishes all histological subtypes of RCC from normal kidney tissues with 84.5% accuracy. On the basis of independent test data reflecting distinct patient populations, the classifier achieves 85.4% and 91.2% accuracy on a Stanford test set (20 normal and 28 RCC) and a Baylor-UT Austin test set (16 normal and 41 RCC), respectively. The majority of the model's selected features show consistent trends across data sets affirming its stable performance, where the suppression of arachidonic acid metabolism is identified as a shared molecular feature of ccRCC and pRCC.

CONCLUSION

Together, these results indicate that signatures derived from DESI-MSI combined with machine learning may be used to rapidly determine surgical margin status with accuracies that meet or exceed those reported for IFS.

The impact of routine frozen section analysis during nephroureterectomy or segmental ureterectomy for urothelial carcinoma on final surgical margin status and long-term oncologic outcome

OBJECTIVE

The utility of intraoperative frozen section analysis (FSA) at the surgical margins (SMs) in patients with upper urinary tract cancer has not been established. We herein assessed the clinical significance of routine FSA of ureteral SMs during nephroureterectomy (NU) or segmental ureterectomy (SU).

MATERIALS AND METHODS

A retrospective review of our Surgical Pathology database identified consecutive patients undergoing NU (n=246) or SU (n=42) for urothelial carcinoma from 2004 to 2018. FSA (n=54) was correlated with the diagnosis of frozen section controls, the status of final SMs, and the prognosis of patients.

RESULTS

During NU, FSA was performed in 19 (7.7%) patients and was significantly more often requested in cases with ureteral tumor (13.1%) than in those with renal pelvis/calyx tumor (3.5%). Final SMs at the distal ureter/bladder cuff were positive only in non-FSA cases in the entire NU cohort (8.4%; P=0.375) or those with tumor at the lower ureter (57.6%; P=0.046), but not in any of FSA patients (0%). During SU, FSA was performed in 35 (83.3%) cases, including 19 at either proximal or distal SM and 16 at both SMs (SU-FSA2). Final positive SMs were significantly more often detected in non-FSA patients (42.9%) than in all FSA (8.6%; P=0.048) or SU-FSA2 (0%; P=0.020) patients. Overall, FSAs were reported as positive or high-grade carcinoma (n=7), atypical or dysplasia (n=13), and negative (n=34), and all these diagnoses were confirmed accurate on the frozen section controls, except one with a revision from atypical to carcinoma in situ. Meanwhile, 16 (80.0%) of 20 cases with initial positive/atypical FSA achieved negative conversion by excision of additional tissue. Kaplan-Meier analysis revealed that SU-FSA did not significantly reduce the risk of tumor recurrence in the bladder, disease progression, or cancer-specific mortality. Nonetheless, NU-FSA was strongly associated with reduced progression-free (P=0.023) and cancer-specific (P=0.007) survival rates, compared with non-FSA, which may imply a selection bias (e.g., FSA for clinically more aggressive tumors).

CONCLUSIONS

Performing FSA during NU for lower ureteral tumor, as well as during SU, significantly reduced the risk of positive SMs. However, routine FSA for upper urinary tract cancer failed to considerably improve long-term oncologic outcome.

The complementary value of intraoperative fluorescence imaging and Raman spectroscopy for cancer surgery: combining the incompatibles

A clear margin is an important prognostic factor for most solid tumours treated by surgery. Intraoperative fluorescence imaging using exogenous tumour-specific fluorescent agents has shown particular benefit in improving complete resection of tumour tissue. However, signal processing for fluorescence imaging is complex, and fluorescence signal intensity does not always perfectly correlate with tumour location. Raman spectroscopy has the capacity to accurately differentiate between malignant and healthy tissue based on their molecular composition. In Raman spectroscopy, specificity is uniquely high, but signal intensity is weak and Raman measurements are mainly performed in a point-wise manner on microscopic tissue volumes, making whole-field assessment temporally unfeasible. In this review, we describe the state-of-the-art of both optical techniques, paying special attention to the combined intraoperative application of fluorescence imaging and Raman spectroscopy in current clinical research. We demonstrate how these techniques are complementary and address the technical challenges that have traditionally led them to be considered mutually exclusive for clinical implementation. Finally, we present a novel strategy that exploits the optimal characteristics of both modalities to facilitate resection with clear surgical margins.

Intraoperative pathology consultation during urological surgery: Impact on final margin status and pitfalls of frozen section diagnosis

Despite recent improvements in diagnostic and surgical techniques in urological oncology, positive resection margin remains a significant concern for surgeons. Meanwhile, intraoperative pathology consultation with frozen section assessment (FSA), particularly for histological diagnosis of the lesions incidentally found or enlarged or sentinel lymph nodes, generally provides critical information which enables immediate decision making for optimal patient care. The intraoperative evaluation of surgical margins is also often requested, although there are some differences in its application between institutions and surgeons. Importantly, it remains to be determined whether intraoperative FSA indeed contributes to reducing the risk of final positive margins and thereby improving long-term patient outcomes. This review summarizes available data indicating the potential impact of FSA at the surgical margins during urological surgeries, including radical or partial cystectomy, partial nephrectomy, radical prostatectomy, penectomy, and orchiectomy. The accuracy and pitfalls of the intraoperative consultation/FSA diagnosis are also discussed.

Radical cystectomy: do we need standardization?

INTRODUCTION

The first series of radical cystectomy with a definition of surgical landmarks was published in 1949 and was characterized by a high perioperative mortality and a 5-year survival rate around 50%. Decades later, nevertheless many surgical progresses were made and the perioperative mortality dropped to 2,5%, this had not lead to an improvement of long term survival rates, also because a standardization of the procedure is still missing. Areas covered: Radical cystectomy is performed with different surgical techniques obmitting a standardization. The comparability of many studies is therefore difficult or havely compromised. A paragon with other diciplines was made emphazing that there high surgical quality is defined, measured and controlled. A systematic literature search was made selecting finally 76 article adressing this issue. Expert commentary: Surgical guidelines in uro-oncology are vague and a definition of surgical quality is missing. A view outside of the box could be very helpful. This is a plea for a change.