Validation of a prediction model for low volume/low grade cancer: application in selecting patients for active surveillance

Performance of systematic, MRI-targeted biopsies alone or in combination for the prediction of unfavourable disease in MRI-positive low-risk prostate cancer patients eligible for active surveillance

PURPOSE

To assess the upstaging/upgrading rates of low-risk prostate cancer (PCa) according to the biopsy scheme used (systematic (SB), targeted biopsies (TB), or both) in the setting of positive pre-biopsy MRI.

PATIENTS AND METHODS

We included 143 consecutive men fulfilling the Toronto University active surveillance (AS) criteria who underwent a pre-biopsy positive MRI, a combination of SB and software-based fusion TB, and a radical prostatectomy, in two expert centres. The primary endpoints were the pathological upgrading and upstaging rates. Overall unfavourable disease (OUD) was defined by any pT3-4 and/or pN1 and/or ≥ GG 3.

RESULTS

Using TB alone would have missed 21.7% of cancers including 16.7% of ≥ GG 3. The use of TB was significantly associated with a lower risk of ≥ Grade Group (GG) 3 disease (p < 0.006) in RP specimens. Combination of SB and TB lowered this risk by 39%, compared with TB alone. The biopsy scheme did not affect the upstaging rates which were substantial even in case of combination scheme (from 37 to 46%). OUD was detected in approximately 50% of cases. The presence of high grade on TB was the only independent predictive factor for both ≥ GG 2 (p = 0.015) and ≥ GG 3 (p = 0.023) in RP specimens.

CONCLUSIONS

High grade on TB biopsies represented the major predictor of upgrading. Combination of SB and TB better defined the sub-group of patients having the lowest risk of reclassification, compared with TB or SB alone. The risk of non-organ-confined disease remained high, and could not be accurately predicted by MRI or systematic/targeted biopsy features.

Does cumulative prostate cancer length (CCL) in prostate biopsies improve prediction of clinically insignificant cancer at radical prostatectomy in patients eligible for active surveillance?

OBJECTIVES

To evaluate if cumulative prostate cancer length (CCL) on prostate needle biopsy divided by the number of biopsy cores (CCL/core) could improve prediction of insignificant cancer on radical prostatectomy (RP) in patients with prostate cancer eligible for active surveillance (AS).

PATIENTS AND METHODS

Patients diagnosed with prostate cancer on extended (≥10 cores) biopsy with an initial prostate-specific antigen (iPSA) level of <15 ng/mL, clinical stage (cT) ≤ 2a, and highest biopsy Gleason score 3 + 3 = 6 or 3 + 4 = 7 with <3 positive cores who underwent RP were included in the study. The CCL/core and presence of insignificant cancer (organ-confined, volume <0.5 mL, Gleason score at RP ≤6) were recorded. pT2 prostate cancer with RP Gleason score ≤3 + 4 = 7 and volume <0.5 mL were categorised as low-tumour-volume organ-confined disease (LV-OCD).

RESULTS

In all, 221 patients met the inclusion criteria: the mean age was 59 years and the median iPSA level was 4.5 ng/mL. The clinical stage was cT1 in 86% of patients; biopsy Gleason score was 3 + 3 = 6 in 67% (group 1) and 3 + 4 = 7 in 33% of patients (group 2). The maximum percentage of biopsy core involvement was <50 in 85%; the median CCL/core was 0.15 mm. Insignificant cancer was found in 27% and LV-OCD in 44% of patients. Group 2 was associated with higher number of positive cores, maximum percentage core involvement, total prostate cancer length, and CCL/core. Group 1 was more likely to have insignificant cancer (39%) or LV-OCD (54%) than group 2 (3% and 23%, respectively). Group 2 had significantly higher RP Gleason score and pathological stage. Univariate analysis of group 1 showed that the iPSA level, maximum percentage core involvement, prostate cancer length, and CCL/core were all significantly associated with insignificant cancer and LV-OCD. For group 2, the number of positive cores (1 vs 2) was also significantly associated with LV-OCD. On multivariate logistic regression analysis, maximum percentage core involvement of <50, and number of positive cores (1 vs 2) were independent predictors of insignificant cancer in group 1; biopsy Gleason score, maximum percentage core involvement of <50 and prostate cancer length of <3 mm or CCL/core of <0.2 mm were all independent predictors of LV-OCD in the whole population. The maximum percentage of core involvement of <50 and prostate cancer length of <3 mm or CCL/core of <0.2 mm were also independent predictors of LV-OCD in group 1 patients.

CONCLUSION

In patients eligible for AS, a CCL/core of <0.20 mm was significantly associated with insignificant cancer and LV-OCD. However, when parameters of cancer burden were considered, CCL/core did not independently add any additional value for predicting insignificant cancer in patients with biopsy Gleason score 6. The CCL/core was an independent predictor of LV-OCD in the whole population and in group 1 patients, although the model including prostate cancer length showed slightly higher area under the receiver operating characteristic curve.

Single foci prostate cancer: current diagnosis and management

Diagnosis of small prostate cancer foci is a real challenge for pathologists and urologists as it carries the risk of false positive or negative diagnosis with clinical consequences. Diagnosis of small prostate cancer foci requires a strict methodological approach which includes a search for major and minor features under low and high magnification. Ambiguous cases can be further clarified with the use of basal cell immunomarkers complemented by a positive indicator of malignancy. Despite the new diagnostic armamentarium, a few cases will continue to remain doubtful and might require an appropriate rebiopsy.

Assessment of circulating tumor cells (CTCs) in prostate cancer patients with low-volume tumors

The objective of this study was to assess the incidence of circulating tumor cells (CTCs) in prostate cancer patients with low-volume tumors (less than 0.5 cc) after radical prostatectomy (RP). Blood samples were collected from 64 RP patients to assess the incidence of CTCs following RP. The specimens were processed by whole-mount section. Clinicopathological data (e.g. patient age, race, specimen weight, tumor volume, grade, stage and surgical margin status) and follow-up PSA data were compared to CTC status. Of the 64 RP patients, nine had 'low-volume prostate cancer'. Seven of these patients had detectable levels of CTCs. In two of the seven patients with detectable CTCs, PSA elevation was also observed. Isolation and detection of circulating epithelial cells is possible in low-volume prostate cancer patients. In the setting of low-volume prostate cancer, CTCs may be associated with the presence of detectable PSA levels. However, the detection of CTCs did not predict PSA failure.

Does the size matter?: Prostate weight does not predict PSA recurrence after radical prostatectomy

Previous studies suggest that low prostate weight is a significant negative prognostic factor for prostate cancer. In the current study, the data for 431 men who underwent radical retropubic prostatectomy between 1990 and 1998 were analyzed for association between prostate weight and various clinical and pathologic parameters. These included age, preoperative prostate-specific antigen (PSA) level, PSA recurrence, pathologic stage, Gleason grade, extraprostatic extension, positive surgical margins, tumor volume, associated high-grade prostatic intraepithelial neoplasia, perineural invasion, and lymph node metastasis. Potential associations were probed by using Cox regression model analysis. A significant positive correlation was found between prostate weight and increasing patient age or increasing preoperative PSA level. There was no significant independent association between prostate weight and any of the other variables examined. No association was found between prostate weight and PSA recurrence. Although increasing prostate weight correlates with increased patient age and higher preoperative PSA level, it does not independently predict postoperative cancer recurrence.

Radical prostatectomy findings in patients predicted to have low-volume/low-grade prostate cancer diagnosed by extended-core biopsies: an analysis of volume and zonal distribution of tumour foci

OBJECTIVE

To measure total tumour volume (TTV) and dominant TV (DTV) in radical prostatectomy (RP) specimens from patients predicted to have low-volume, low-grade (LV/LG) prostate cancer, as this entity can be predicted from biopsy findings and prostate-specific antigen (PSA) level, but tumour under-sampling remains a challenge in active surveillance programmes.

PATIENTS AND METHODS

This was a retrospective study from an academic centre, of men with prostate cancer treated from 2000 to 2007, with a PSA level of <10 ng/mL and one core of cancer from an extended scheme showing either Gleason score (GS) 3 + 3 of <3.0 mm or 3 + 4 of <2.0 mm. All men had RP, and the TTV, DTV, tumour location, pathological GS and stage were measured.

RESULTS

Of 3055 RPs, 66 (2.1%) met the inclusion criteria. The core with cancer was from a sextant and alternative site in 26 (39%) and 40 (61%) patients, respectively. A pathological GS 3 + 3 or 3 + 4 was assigned to 94%, while 6% were GS > or = 4 + 3; all 66 tumours were organ-confined. The median (range) TTV and DTV were 0.15 (0.0008-5.06) and 0.14 (0.0008-5.04) mL, respectively. The median number of tumour foci was 3 (1-7), being unifocal in 17/66 (26%) and multifocal in 49/66 (74%). The transition zone was involved in 29% of unifocal and 71% of multifocal tumours. Of all 66 patients, the TTV was <0.5 mL in 47 (71%), and of 59 patients with biopsy GS 3 + 3, 33 (56%) had a TTV of <0.5 mL and pathological GS 3 + 3. Of 19 patients with a TTV of > or =0.5 mL, the median TTV was 1.06 (0.51-5.05) mL, with tumour foci of transition zone origin in 16 (84%). The study was limited by its retrospective design and small sample size.

CONCLUSIONS

Using conservative selection criteria for predicting LV/LG cancer, RP specimens showed organ-confined disease in all cases, upgrading to GS > or = 4 + 3 in 6%, and TTV <0.5 mL in 71% of cases. The transition zone is a common location of under-sampled disease.

[Active surveillance of localized prostate cancer. Significance of prostate core needle biopsies]

Today, more than 80% of men diagnosed with prostate cancer (PCA) by PSA screening do not die from the sequelae of their disease. About 70% present with early, organ-confined cancer and almost half of them are small (<5 cm(3)) without evidence of progression over years (insignificant PCA). It is assumed that screening brings the diagnosis of PCA forward by about 9 years and that in almost one third of these cases immediate radical prostatectomy or radiotherapy would result in overtreatment. Thus, the treatment strategy of "active surveillance" with selective but delayed intervention for patients with organ-confined PCA could be an attractive alternative to the known curative therapy options. However, a prerequisite of such a therapeutic approach would be a precise identification of patients at high risk for cancer progression. Careful work-up of prostate core needle biopsies including improved pre-embedding preparation and detailed interpretation are of the utmost importance. A Gleason score < or =6 and tumor in only one or two cores are considered predictive of organ-confined cancer. Pathologists should concentrate on correct Gleason scoring in core needle biopsies and identification of lesions that exclude a patient from active surveillance.

Do patients with low volume prostate cancer have prostate specific antigen recurrence following radical prostatectomy?

Aims:

The objective of this study was to determine the incidence of prostate specific antigen (PSA) relapse in patients with low volume prostate cancer following radical prostatectomy.

Methods:

Between 1993 and 2001, 50 of 717 patients had total tumour volumes of less than 0.5 cm3 following radical prostatectomy. Biochemical recurrence was defined as two consecutive values of serum PSA levels of 0.2 ng/ml or greater.

Results:

Median follow-up of the 50 patients was 58 months. In five of the 50 patients (10%), PSA recurrence was observed. All of these five cases had Gleason score of 3+3 (well and/or moderately differentiated), organ confined and surgical margin negative tumours. In three of the five cases, capsular incision resulted in benign glands extending into the surgical margin.

Conclusions:

Five of 50 cases had PSA failure. In three of the five patients, benign glands located in the margin could explain the “PSA recurrence”. However, in the other two patients, none of the pathological parameters correlated with measurable PSA levels. The explanation for their PSA failure is unclear.

Expectant management of prostate cancer with curative intent: an update of the Johns Hopkins experience

PURPOSE

We updated our experience with a strategy of expectant treatment for men with stage T1c prostate cancer and evaluated predictors of disease intervention.

MATERIALS AND METHODS

A total of 407 men with a median age of 65.7 years (range 45.8 to 81.5) with stage T1c (99.8%) or T2a (0.2%) prostate cancer suspected of harboring small volume prostate cancer based on needle biopsy findings and prostate specific antigen density have been followed in a prospective, longitudinal surveillance program with a median followup of 2.8 years (range 0.4 to 12.5). A recommendation for treatment was made if disease progression was suggested by unfavorable followup needle biopsy findings (Gleason pattern 4 or 5, greater than 2 biopsy cores with cancer or greater than 50% involvement of any core with cancer). Cox proportional hazards regression was used to evaluate the affect of multiple covariates on the outcome of curative intervention.

RESULTS

Of 407 men 239 (59%) men remained on active surveillance at a median followup of 3.4 years (range 0.43 to 12.5), 103 (25%) underwent curative intervention at a median of 2.2 years after diagnosis (range 0.96 to 7.39) and 65 (16%) were either lost to followup (12), withdrew from the program (45), or died of causes other than prostate cancer (8). Older age at diagnosis (p = 0.011) and an earlier date of diagnosis (p = 0.001) were significantly associated with curative intervention.

CONCLUSIONS

Recognizing that over treatment of prostate cancer is prevalent, especially among elderly patients, a program of careful selection and monitoring of older men who are likely to harbor small volume, low grade disease may be a rational alternative to the active treatment of all.