Quantification of tumor cell burden by analysis of single cell lymph node disaggregates in metastatic prostate cancer.

BACKGROUND: The size of lymph node (LN) metastases in prostate cancer patients represents an important prognosticator, but histological work-up may not reflect the true extent of tumor invasion. We present a novel technique (1) to detect early tumor cell dissemination and (2) to quantify the true tumor burden. METHODS: Prospectively 232 LN of 20 consecutive patients with prostate cancer after lymph node dissection were longitudinally bisected, one half was subjected to single cell immunocytochemistry for pancytokeratine (CK), the other half underwent routine histopathological work-up and step section analysis. In immunocytochemistry, tumor cell density (TCD) was quantified by calculating the number of CK-positive cells/million leucocytes and compared to routine histopathology and step section analysis. RESULTS: Eight of 20 patients were positive in histopathology and step sectioning, but 14 of 20 patients were positive in single cell analysis. Twenty-five of 232 LN were positive in routine histopathology, whereas 52 of 232 LN were positive in single cell analysis. Median TCD in histopathologically positive LN was 3060.0 x 10(-6) and 9.9 x 10(-6) in histopathologically negative LN (P < 0.0001). Mean TCD of histopathologically negative LN of pN1 patients was significantly higher than the mean TCD of pN0 patients (P < 0.003). Mean TCD per patient correlated with serum-PSA (r(2) = 0.48, P < 0.006). CONCLUSIONS: Single cell analysis has an increased detection rate compared to routine histopathology and even to serial step section analysis. The method can detect early tumor dissemination and enables quantification of the tumor burden. The subgroup of histopathologically negative LN with CK-positive cells represents tumor cell dissemination not depicted histologically.

Activation of mTOR in renal cell carcinoma is due to increased phosphorylation rather than protein overexpression.

The altered expression and activation of the mammalian target of rapamycin (mTOR) promotes the invasiveness and metastatic potential in a variety of malignancies. The aim of the present pilot study was to determine mTOR expression in clear cell renal cell carcinoma (RCC) and to evaluate mTOR activation and phosphorylation at Ser2448. Tissue microarray immunohistochemistry and Western blot analysis of tumor and benign tissue from 10 patients subjected to tumor nephrectomy were investigated. Staining of mTOR and phosphorylated-mTOR (p-mTOR) was documented and determined as percentage of the maximum. Western blots were evaluated densitometrically. Ratios of tumor versus benign tissue were calculated and compared by the Wilcoxon/Kruskal-Wallis test. Immunohistochemical expressions of mTOR and p-mTOR were 49 and 40% in benign renal parenchyma, whereas it was 20 and 42% in tumor tissue. Ratios of tumor versus benign tissue revealed a reduction to 0.44 for mTOR and corresponding elevation to 1.29 for p-mTOR (p<0.05). The rate of p-mTOR to mTOR was 1.19 in benign, whereas it was 5.30 in tumor tissue. Western blot densitometry detected lower expressions of mTOR in tumor compared to benign tissues. Ratio of p-mTOR to mTOR were significantly different in benign versus tumor tissue (0.86 vs. 1.37; p<0.04). The observation that RCC specimens exhibit higher levels of p-mTOR in RCC compared to benign renal parenchyma indicate the role of mTOR phosphorylation in RCC tumor development and progression. This study found a concomitant reduction of the RCC mTOR protein expression, which suggests that elevated levels of activated p-mTOR result predominantly from an increased mTOR phosphorylation rather than from protein overexpression. These pilot study results may contribute to the clarification of mTOR-pathway regulation processes in RCC on the way to the protein profiling-predicted targeted therapy.

Combinations of urine-based tumour markers in bladder cancer surveillance.

OBJECTIVE: The aim of the study was to investigate whether combinations of urine-based tumour markers including urinary cytology (Cytology or Cyt) increase the sensitivity in the detection of bladder cancer recurrence. MATERIAL AND METHODS: Urinary cytology, NMP22, UroVysion (FISH) and ImmunoCyt (uCyt+) were determined in 221 patients during the follow-up of non-muscle-invasive transitional cell carcinoma (NMI TCC) before cystoscopy (n = 49) or with the suspicion of TCC recurrence before transurethral resection of the bladder (n = 173). For all markers alone as well as in all possible combinations (multimarker panels, MPs) sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were evaluated. MPs were considered positive if at least one marker was positive. RESULTS: No malignancy was found in 108 patients, whereas recurrent TCC was confirmed in 113 patients. Sensitivity and specificity for Cytology were 84% and 62%, for NMP22 68% and 49%, for FISH 72% and 63%, and for uCyt+ 73% and 62%, respectively. The NPV was below 80% for all markers alone. Combinations of two and three markers increased the sensitivity as well as the NPV to over 90 and 80%, by reducing specificity to an average of 44% and 35%, respectively. The most sensitive combinations were NMP22, uCyt+ together with Cytology and FISH, and uCyt+ together with NMP22 (sensitivity for both combinations 98%). There was no further improvement when all four markers were combined. CONCLUSIONS: Combinations of tumour markers increased the sensitivity and NPV in the detection of recurrence of NMI TCC. A stepwise approach of tumour marker determination may be used to reduce the frequency of follow-up cystoscopies at a reasonable risk.