[Postoperative prognosis of chromophobic renal cell carcinoma: comparative analysis of the multinational CORONA database].

BACKGROUND

The chromophobe subtype represents the third most common histological subtype of renal cell carcinoma (chRCC). Due to the rarity of this subtype only one publication regarding the specific analysis of clinical and histopathological criteria as well as survival analysis of more than 200 patients with chRCC is known to date.

MATERIALS AND METHODS

A total of 6,234 RCC patients from 11 centres who were treated by (partial) nephrectomy are contained in the database of this multinational study. Of the patients 259 were diagnosed with chRCC (4.2 %) and thus formed the study group for this retrospective investigation. These subjects were compared to 4,994 patients with a clear cell subtype (80.1 %) with respect to clinical and histopathological criteria. The independent influence of the chromophobe subtype regarding tumor-specific survival and overall survival was determined using analysis by Cox proportional hazards regression models. The median follow-up was 59 months (interquartile range 29-106 months).

RESULTS

The chRCC patients were significantly younger (60 vs. 63.2 years, p < 0.001), more often female (50 vs. 41 %, p = 0.005) and showed simultaneous distant metastases to a lesser extent (3.5 vs. 7.1 %, p = 0.023) compared to patients with a clear cell subtype. Despite a comparable median tumor size a ≥ pT3 tumor stage was diagnosed in only 24.7 % of the patients compared to of 30.5 % in patients with a clear cell subtype (p = 0.047). In addition to the clinical criteria of age, sex and distant metastases, the histological variables pTN stage, grade and tumor size showed a significant influence on tumor-specific and overall survival. However, in the multivariable Cox regression analysis no independent effect on tumor-specific mortality (HR 0.88, p = 0.515) and overall mortality (HR 1.00, p = 0.998) due to the histological subtype was found (c-index 0.86 and 0.77, respectively).

CONCLUSIONS

Patients with chRCC and clear cell RCC differ significantly concerning the distribution of clinical and histopathological criteria. Patients with chRCC present with less advanced tumors which leads to better tumor-specific survival rates in general; however, this advantage could not be verified after adjustment for the established risk factors.