Kidney cancer subtype study finds low recurrence and cancer death rates

Patients with papillary renal cell carcinoma, the second most common kidney cancer subtype, face a low risk of tumour recurrence and cancer-related death after surgery. Those are the key findings of a multi-centre study of nearly 600 patients published in the April issue of the urology journal BJUI.

"Because papillary renal cell carcinoma (pRCC) only affects ten to 15% of kidney cancer patients, the small number of patients enrolled in individual studies makes it hard to draw meaningful conclusions about how the disease will progress" says lead author Dr Vincenzo Ficarra, associate professor of urology at the University of Padua, Italy.

"Bringing together data on 577 patients from 16 academic centres across Italy has enabled us to study this subtype in more detail than a single-centre study would allow."

The patients with pRCC were identified from 5,463 patients with suspected renal cell carcinoma at the centres between 1995 and 2007. Follow-up ranged from 22 to 72 months and the median was just over 39 months.

Key findings of the study, which forms part of a larger research project promoted by LUNA, the clinical research office of the Italian Society of Urology, include:

• Patients averaged 62.4 years of age and 77% were male. The majority had presented with incidental symptoms (64%) and the size of the pathological tumours ranged from 3cm to 7cm, with a median size of 4.3cm.
• Most patients (62%) had radical nephrectomy surgery, where the entire kidney and its collecting system is removed, along with the adrenal gland, the fat tissue around the kidney and the associated lymph glands.
• At follow-up, 81% of the patients were alive and disease free. A further 14% had experienced disease progression, 11% had died from the disease and 5% had died from causes other than cancer.
• The overall average recurrence-free survival rates after surgery were 85.5% and 73.1% respectively. The cancer-specific survival rates after surgery were 87.9% at five years and 83.3% after ten years.
• Multivariable analysis, which determines the relative contributions of different causes to a single event, identified three independent predictors of recurrence-free survival rates. These were: Fuhrman nuclear grade (predictive grading system for renal cell cancer), N stage (coding system indicating absence or presence of secondary cancer in the regional lymph nodes) and M stage (coding system indicating absence or presence of distant secondary cancers at first therapeutic intervention).
• In this study 60% of patients were N stage pNx (regional nodes cannot be assessed), 97% were M stage MO (no indication that cancer has spread to distant parts of the body), 52% were Fuhrman grade G2 (low grade in a grading system of one to four) and 10% of patients had tumours at multiple sites.
• Fuhrman nuclear grade was found to be a particularly strong predictor of both recurrence-free and cancer-specific survival rates. In contrast, only a non-statistically significant trend was found for the 2009 pathological T stage (coding system that identifies the presence, size and extent of a primary tumour).

"Our multi-centre study shows that patients with papillary renal cell carcinoma face low tumour re-occurrence and cancer-related death rates" concludes Dr Ficarra. "It also identifies the main independent predictors of cancer-related outcomes as being pathological lymph node stage, presence of secondary cancer and Fuhrman nuclear grade."