Clinical and molecular rationale to retain the cancer descriptor for Gleason score 6 disease

The Role of Secondary Lesion Biopsy in Detecting Clinically Significant Prostate Cancer

BACKGROUND

Multiparametric MRI (mpMRI) and fusion-targeted biopsy (TB) have improved the detection of clinically significant prostate cancer (csPCa); however, it remains unclear whether secondary lesions (SLs) identified on mpMRI must also be biopsied in addition to the index lesion (IL). Currently, American Urological Association and European Association of Urology guidelines suggest biopsying all lesions, but supporting data are sparse. This study examines whether including SL biopsies provides additional value in csPCa detection compared to IL biopsy alone when systematic biopsy (SB) is also performed.

METHODS

Men with multiple PI-RADS ≥ 3 lesions on mpMRI who underwent prostate biopsy were retrospectively identified. The primary analysis compared csPCa detection rates from SB and IL TB, with or without SL TB. Secondary analyses assessed the impact of prostate-specific antigen (PSA) density and SL PI-RADS scores on csPCa detection. Sensitivity analyses were performed to investigate the robustness of findings.

RESULTS

Among 73 men, csPCa detection rate was 47% with SB and IL biopsy alone and improved to 52% with SL biopsies included (p = 0.62). Secondary analyses showed no significant differences in csPCa detection based on PSA density or SL PI-RADS scores. Two of three sensitivity analyses supported the primary findings.

CONCLUSIONS

Biopsying SLs does not significantly increase csPCa detection rates compared to IL biopsy alone when SB is also performed. This supports the notion that SL biopsies can be safely omitted without compromising clinical outcomes, thereby potentially reducing patient discomfort and procedural costs, and may inform future guideline development and revisions.

Gleason score 3+3=6 prostatic adenocarcinoma is not benign and the current debate is unhelpful to clinicians and patients

Prostate adenocarcinoma is a common malignancy associated with a significant morbidity and mortality. In both prostate biopsies and radical prostatectomy specimens Gleason scoring informs both treatment and outcome prediction. The current convention is that in needle biopsies, Gleason patterns 3, 4 and 5 are considered to be malignant. Despite this there is debate as to whether or not Gleason score (GS) 3+3=6 should be diagnosed as cancer due to potential over-treatment and the psychological impact on patients. It is apparent that GS 3+3=6 is indolent disease with a low risk of metastasis. However, it does have the histological features of malignancy and is capable of infiltrating the prostate gland, extraprostatic extension, and metastatic spread. Furthermore GS 3+3=6 carcinoma has immunohistochemical and molecular genetic features similar to those of higher grade prostatic carcinoma. If GS 3+3=6 tumour is considered benign, the question arises should a benign label be given to the Gleason pattern 3 component of tumour that includes Gleason patterns of higher grade? This would seem a logical step as GS 3+3=6 cancers and the pattern 3 component in cancers with multiple patterns are morphologically identical. If pattern 3 is considered to be benign, then Gleason scoring would be limited to 4+4=8, 4+5=9, 5+4=9 and 5+5=10 which is clearly inappropriate. The correct strategy to address potential over-treatment of patients with low-grade cancer is clinician and patient education, not the recalibration of Gleason grading to reclassify malignant tumours as benign.

High CHK2 protein expression is a strong and independent prognostic feature in ERG negative prostate cancer

Checkpoint kinase 2 (CHK2) is a serine-threonine kinase with a role in DNA repair, cell cycle arrest or apoptosis in response to DNA damage. Both reduced and increased CHK2 expression has been described in different tumour types with impact on patient prognosis. To evaluate prevalence and significance of altered CHK2 expression in prostate cancer, a tissue microarray containing 17,747 tumours was analysed by immunohistochemistry. Nuclear CHK2 immunostaining was absent or weak in benign prostate epithelium but often more prominent in cancers. CHK2 immunostaining was considered weak in 38.8%, moderate in 33.6% and strong in 11.2% of prostate cancers. High CHK2 expression was strongly associated with TMPRSS2:ERG fusions (p<0.0001). Subgroup analysis of ERG positive and negative cancers revealed that high CHK2 staining was significantly linked to advanced tumour stage, high Gleason score, positive nodal status, positive surgical margin, high preoperative PSA (p<0.0001 each) and early prostate-specific antigen (PSA) recurrence (p=0.0001) in the subset of ERG negative cancers, while most of these associations were absent in ERG positive cancers. In ERG negative cancers, high CHK2 expression was an independent predictor of patient prognosis, even if parameters were included that were only available postoperatively. High CHK2 expression was also linked to presence of chromosomal deletions, high level of androgen receptor expression, positive p53 immunostaining, and high Ki-67 labelling index. These provide further in vivo evidence for previously described functional interactions. In summary, high CHK2 expression is linked to adverse tumour features and independently predicts early biochemical recurrence in ERG negative prostate cancer. CHK2 measurement, either alone or in combination, might be of clinical utility in this prostate cancer subgroup.

Identification and evaluation of clinically significant prostate cancer: a step towards personalized diagnosis

PURPOSE OF REVIEW

Prostate cancer (PCa) diagnostics are evolving rapidly. The quest to differentiate 'clinically significant' from 'clinically insignificant' disease has gathered momentum, leading to substantial change in traditional diagnostic approaches. Herein, we review the relevant information on currently available biomarkers and assess their ability to help physicians and patients in making a shared and personalized decision based on their individual risk of harbouring clinically significant disease.

RECENT FINDINGS

Serum, urine, tissue and imaging biomarkers have been evaluated to improve the identification of clinically significant disease, and this international effort has yielded promising, but not always consistent results. Changes in MRI technology have realized a quantum change, and this facility is now becoming more widely incorporated into diagnostic and disease risk-stratification protocols. However, standardization and further validation is required.

SUMMARY

Acceptance and widespread adoption of serum, urine and genetic markers is awaited, but novel and promising techniques alone and in combination have emerged. With validation and further focus, these may be adopted more widely.