'High proliferative cribriform prostate cancer' defines a patient subgroup with an inferior prognosis

GRIN3A: A biomarker associated with a cribriform pattern and poor prognosis in prostate cancer

Prostate cancer with a cribriform pattern, including invasive cribriform carcinoma (ICC) and/or intraductal carcinoma (IDC) is associated with a poor prognosis, and the underlying mechanisms are unclear. Therefore, we aimed to identify biomarkers for this feature. Using a radical prostatectomy cohort, we performed within-patient differential expression analyses with RNA sequencing data to compare samples with a cribriform pattern to those with non-cribriform Gleason pattern 4 (NcGP4; n=13). ACSM1, GRIN3A, PCDHB2, and REG4 were identified as differentially expressed, and validation was performed using real-time reverse transcription polymerase chain reaction (n=99; 321 RNA samples) and RNA in situ hybridization on tissue microarrays (n=479; 2047 tissue cores). GRIN3A was significantly higher expressed in cribriform pattern vs. NcGP4, when assessed within the same patient (n=27; p=0.005) and between different patients (n=83; p=0.001). Tissue cores with IDC more often expressed GRIN3A compared to ICC, NcGP4, and benign tissue (52 % vs. ≤ 32 %). When IDC and NcGP4 was compared within the same patient (173 pairs of tissue cores; 54 patients), 38 (22 %) of the tissue microarray core pairs had GRIN3A expression in only IDC, 33 (19 %) had expression in both IDC and NcGP4, 14 (8 %) in only NcGP4 and 88 (51 %) were negative in both entities (p=0.001). GRIN3A was as well associated with biochemical recurrence (log-rank, p=0.002). In conclusion, ectopic GRIN3A expression is an RNA-based biomarker for the presence of cribriform prostate cancer, particularly for IDC.

Prostate cancer: Molecular aspects, consequences, and opportunities of the multifocal nature

Prostate cancer is unique compared to other major cancers due to the presence of multiple primary malignant foci in the majority of patients at the time of diagnosis. Each malignant focus has distinct somatic mutations and gene expression patterns, which represents a challenge for the development of prognostic tests for localized prostate cancer. Additionally, the molecular heterogeneity of advanced prostate cancer has important implications for management, particularly for patients with metastatic and locally recurrent cancer. Studies have shown that prostate cancers with mutations in DNA damage response genes are more sensitive to drugs inhibiting the poly ADP-ribose polymerase (PARP) enzyme. However, testing for such mutations should consider both spatial and temporal heterogeneity. Here, we summarize studies where multiregional genomics and transcriptomics analyses have been performed for primary prostate cancer. We further discuss the vast interfocal heterogeneity and how prognostic biomarkers and a molecular definition of the index tumor should be developed. The concept of focal treatments in prostate cancer has been evolving as a demand from patients and clinicians and is one example where there is a need for defining an index tumor. Here, biomarkers must have proven value for individual malignant foci. The potential discovery and implementation of biomarkers that are agnostic to heterogeneity are also explored as an alternative to multisample testing. Thus, deciding upon whole-organ treatment, such as radical prostatectomy, should depend on information from biomarkers which are informative for the whole organ.

Addition of cribriform pattern 4 and intraductal prostatic carcinoma into the CAPRA-S tool improves post-radical prostatectomy patient stratification in a multi-institutional cohort

AIMS

Pre-surgical risk classification tools for prostate cancer have shown better patient stratification with the addition of cribriform pattern 4 (CC) and intraductal prostatic carcinoma (IDC) identified in biopsies. Here, we analyse the additional prognostic impact of CC/IDC observed in prostatectomies using Cancer of Prostate Risk Assessment post-surgical (CAPRA-S) stratification.

METHODS

A retrospective cohort of treatment-naïve radical prostatectomy specimens from three North American academic institutions (2010-2018) was assessed for the presence of CC/IDC. Patients were classified, after calculating the CAPRA-S scores, into low-risk (0-2), intermediate-risk (3-5) and high-risk (6-12) groups. Kaplan-Meier curves were created to estimate biochemical recurrence (BCR)-free survival. Prognostic performance was examined using Harrell's concordance index, and the effects of CC/IDC within each risk group were evaluated using the Cox proportional hazards models.

RESULTS

Our cohort included 825 prostatectomies (grade group (GG)1, n=94; GG2, n=475; GG3, n=185; GG4, n=13; GG5, n=58). CC/IDC was present in 341 (41%) prostatectomies. With a median follow-up of 4.2 years (range 2.9-6.4), 166 (20%) patients experienced BCR. The CAPRA-S low-risk, intermediate-risk and high-risk groups comprised 357 (43%), 328 (40%) and 140 (17%) patients, and discriminated for BCR-free survival (p<0.0001). For CAPRA-S scores 3-5, the addition of CC/IDC status improved stratification for BCR (HR 2.27, 95% CI 1.41 to 3.66, p<0.001) and improved the overall c-index (0.689 vs 0.667, analysis of variance p<0.001).

CONCLUSION

The addition of CC/IDC into the CAPRA-S classification significantly improved post-radical prostatectomy patient stratification for BCR among the intermediate-risk group (CAPRA-S scores 3-5). The reporting of CC and IDC should be included in future prostate cancer stratification tools for improved outcome prediction.