In Focus: Active Surveillance vs Primary Intervention in cT1a Renal Cell Cancer

The DISSRM registry is a multicenter registry across three hospitals offering patients with renal masses <4 cm the option of active surveillance (AS) or primary intervention (PI) since January 2009. A recent publication reports 12-year follow-up data comparing outcomes between these two strategies.

Study Overview

A total of 958 patients were prospectively enrolled, with a median follow-up of approximately 4 years. Of these, 377 chose PI and 581 chose AS. Progression was defined as opting for intervention, a growth rate >0.5 cm/year, or a maximum tumor diameter >4 cm. Patients selecting AS tended to be older, had smaller tumors, and carried more comorbidities.

Outcomes

• Cancer-specific survival (CSS): Only 3 RCC-related deaths occurred—2 in the PI group (due to metastatic recurrence) and 1 in the AS group (sarcomatoid carcinoma in papillary RCC). Thus, CSS was similar between AS and PI.

• Overall survival (OS): OS was higher in patients who chose PI. The unadjusted HR for all-cause mortality was 2.95, reduced to 1.57 after adjustment for age and Charlson Comorbidity Index.

• Tumor growth rate: Median growth was 0.11 cm/year. Interestingly, ~20% of patients had negative growth and another ~20% had zero growth.

• Progression: 216 patients progressed; reasons included elective delayed intervention (DI, n=33), high growth rate (n=114), tumor >4 cm (n=35), or both criteria (n=33). At 5 years, 30% of patients on AS had progressed; at 8 years, 36% had progressed.

• Delayed intervention (DI): Despite progression, only 88 patients crossed over to DI. Larger tumor size strongly predicted crossover to DI.

• Recurrence: Among 377 PI and 88 DI patients, there were 11 recurrences (9 PI, 2 DI), with similar recurrence rates between groups.

Conclusions

The study concluded that AS is a safe and feasible option for patients with small renal masses. Lower OS in the AS group was attributed to competing risks rather than cancer progression, as CSS was equivalent. Tumor growth rate was not associated with recurrence, adverse pathology, or poor CSS, although it strongly predicted DI. In contrast, tumor size was a robust predictor of DI, adverse pathology, recurrence, and metastatic potential, supporting its use as an independent predictor of intervention.

Limitations

The main limitations include the non-randomized design and relatively short follow-up (median ~3 years) despite a 12-year study period. This short follow-up raises caution, particularly for younger patients who may have decades of life ahead. Additionally, there is some evidence that the rate of DI increases over longer follow-up, which should be considered when offering AS to younger patients.