Surgical Complexity and Prognostic Outcome of Small Volume Renal Cell Carcinoma with High-Level Venous Tumor Thrombus and Large Volume Renal Cell Carcinoma with Low-Level Thrombus
Renal cell carcinoma (RCC) is a common malignant tumor of the urinary system, accounting for 2% to 3% of adult malignancies. In locally advanced RCC, 4% to 10% of patients present with inferior vena cava (IVC) tumor thrombus. Patients with untreated RCC associated with IVC tumor thrombus have a poor prognosis, with a median survival time of about 5 months and a 1-year tumor-specific survival rate of approximately 29%. Radical nephrectomy and IVC thrombectomy can significantly improve prognosis, increasing the 5-year tumor-specific survival rate to 40% to 65%. However, radical nephrectomy with IVC thrombectomy is one of the most difficult and complex urological operations due to its extensive surgical trauma, high anesthesia risk, and potential for significant intraoperative bleeding.
The size of the renal tumor is an important index reflecting the complexity of surgery. Generally, larger tumors are more difficult to dissociate and result in more blood loss during the operation. The level of tumor thrombus is also an indicator of surgical complexity. A common clinical problem is that small volume RCC can be associated with high-level tumor thrombus, while large volume RCC can be associated with low-level thrombus. The roles of renal tumor volume and thrombus level in surgical complexity and prognostic outcomes are not well understood. This study aimed to evaluate the surgical complexity and prognostic outcomes between the volume of RCC and the level of venous tumor thrombus.
The clinical data of 67 RCC cases with renal vein or IVC tumor thrombus from January 2015 to May 2018 were retrospectively analyzed. Among these cases, 21 (31.3%) had small tumors with high-level thrombus (tumor ≤7 cm in diameter and thrombus Neves Level II–IV), while 46 (68.7%) had large tumors with low-level thrombus (tumor >7 cm in diameter and thrombus Level 0–I). Clinical features, operation details, and pathology data were collected. Univariable and multivariable logistic regression analyses were applied to evaluate the risk factors for small tumors with high-level thrombus.
Patients with small tumors and high-level thrombus were more likely to have longer operative time (421.9 ± 135.1 minutes vs. 282.2 ± 101.9 minutes, P < 0.001), more surgical bleeding volume (1200 [325, 2900] mL vs. 500 [180, 1000] mL, P = 0.004), more surgical blood transfusion volume (800 [0, 1400] mL vs. 0 [0, 800] mL, P = 0.004), more plasma transfusion volume (0 [0, 800] mL vs. 0 [0, 0] mL, P = 0.004), higher percentage of open operative approach (76.2% vs. 32.6%, P = 0.001), higher percentage of IVC resection (33.3% vs. 0%, P < 0.001), and higher percentage of postoperative complications (52.4% vs. 19.6%, P = 0.010) than patients with large tumors and low-level thrombus. In multivariate analysis, decreased hemoglobin (Hb) (odds ratio [OR]: 0.956, 95% confidence interval [CI]: 0.926–0.986, P = 0.005) and non-sarcomatoid differentiation (OR: 0.050, 95% CI: 0.004–0.664, P = 0.023) were more likely to form small tumors with high-level tumor thrombus rather than large tumors with small tumor thrombus.
The estimated mean cancer-specific survival (CSS) times of small tumors with high-level thrombus and large tumors with low-level thrombus were 31.6 ± 3.8 months and 32.5 ± 2.9 months, respectively, without statistical significance (P = 0.955). After univariate and multivariate Cox proportional hazard survival regression analyses, only distant metastasis (hazard ratio [HR]: 3.839, P = 0.002), sarcomatoid differentiation (HR: 7.923, P < 0.001), alkaline phosphatase (HR: 2.661, P = 0.025), and severe postoperative complications (HR: 10.326, P = 0.001) were independent predictors of prognosis.
The level of the tumor thrombus was more important than the diameter of the primary kidney tumor in affecting the complexity of surgery. In the same T3 stage, neither the renal tumor diameter nor the tumor thrombus level was an independent risk factor for prognosis.
The surgical approach of IVC tumor thrombectomy in this study was described previously. In laparoscopic radical nephrectomy and thrombectomy, all patients underwent a laparoscopic retroperitoneal approach except for those with left RCC with level I–II tumor thrombus, who underwent a retroperitoneal approach to free the kidney combined with a transperitoneal approach to free the IVC if necessary. In open radical nephrectomy and thrombectomy, RCC was treated with a chevron incision through the transperitoneal approach.
The size of the renal tumor is an important index reflecting the complexity of surgery. Generally, larger tumors are more difficult to dissociate and result in more blood loss during the operation. The level of tumor thrombus is also an indicator of surgical complexity. The main steps affecting the surgical complexity of small volume RCC combined with high-level tumor thrombus focused on thrombectomy, not nephrectomy. On the other hand, the main steps affecting the surgical complexity of large volume RCC combined with low-level tumor thrombus focused on nephrectomy, not thrombectomy.
The resection of the IVC vessel wall was also a reference index reflecting the surgical complexity. Literature has shown that the invaded vascular wall should be removed to achieve radical resection of all tumor loads, in order to reduce the local recurrence rate and improve the prognosis. Patients with small tumors and high-level thrombus had a higher incidence of IVC wall resection than those with large tumors and low-level thrombus. The height of the tumor thrombus affected the choice of the surgical method, whether the IVC vessel wall needed resecting or not. For low-grade thrombus, removal of the IVC wall was rarely required. The complications of vascular wall resection, such as bilateral lower extremity edema and renal insufficiency, might also affect the surgical complexity.
Patients with small tumors and high-level thrombus had greater surgical complexity than those with large tumors and low-level thrombus. This was manifested in longer operation time, more bleeding, more surgical blood transfusion, more plasma transfusion, and a higher incidence of complications. Therefore, the height of the tumor thrombus was more important than the diameter of the primary kidney tumor in affecting the complexity of surgery.
The effect of IVC tumor thrombus on prognosis was controversial. Some believed the presence of IVC tumor thrombus affected the prognosis with poor prognosis, while others believed that tumor thrombus had little effect on prognosis. In terms of the prognostic significance of primary renal tumor diameter and the tumor thrombus height, no significant difference was found between small volume tumor with high-level thrombus and large tumor with low-level thrombus. After univariate and multivariate analyses of prognostic factors, only distant metastasis, sarcomatoid differentiation, alkaline phosphatase, and severe postoperative complications were independent predictors of prognosis. In the same T3 stage, neither the renal tumor diameter nor the tumor thrombus height was an independent risk factor for prognosis.
This study had some limitations. The samples were limited to only patients treated by the same hospital and hence similar treatment procedures and practice. Because RCCs with venous extension are relatively uncommon, more extensive study through a consortium that includes more institutes to accumulate more patient data will be very useful. Additionally, the present study was limited by its retrospective and single-center nature. Prospective study and external validation are needed in the future.
In conclusion, the level of the tumor thrombus was more important than the diameter of the primary kidney tumor in affecting the complexity of surgery. In the same T3 stage, neither the renal tumor diameter nor the tumor thrombus level was an independent risk factor for prognosis.
doi.org/10.1097/CM9.0000000000000352
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