Abiraterone acetate and castration resistant ductal adenocarcinoma of the prostate

Optimizing the diagnosis and management of ductal prostate cancer

Ductal adenocarcinoma (DAC) is the most common variant histological subtype of prostate carcinoma and has an aggressive clinical course. DAC is usually characterized and treated as high-risk prostatic acinar adenocarcinoma (PAC). However, DAC has a different biology to that of acinar disease, which often poses a challenge for both diagnosis and management. DAC can be difficult to identify using conventional diagnostic modalities such as serum PSA levels and multiparametric MRI, and the optimal management for localized DAC is unknown owing to the rarity of the disease. Following definitive therapy for localized disease with radical prostatectomy or radiotherapy, the majority of DACs recur with visceral metastases at low PSA levels. Various systemic therapies that have been shown to be effective in high-risk PAC have limited use in treating DAC. Although current understanding of the biology of DAC is limited, genomic analyses have provided insights into the pathology behind its aggressive behaviour and potential future therapeutic targets.

Integrative Genomic Analysis of Coincident Cancer Foci Implicates CTNNB1 and PTEN Alterations in Ductal Prostate Cancer

BACKGROUND

Ductal adenocarcinoma of the prostate is an aggressive subtype, with high rates of biochemical recurrence and overall poor prognosis. It is frequently found coincident with conventional acinar adenocarcinoma. The genomic features driving evolution to its ductal histology and the biology associated with its poor prognosis remain unknown.

OBJECTIVE

To characterize genomic features distinguishing ductal adenocarcinoma from coincident acinar adenocarcinoma foci from the same patient.

DESIGN, SETTING, AND PARTICIPANTS

Ten patients with coincident acinar and ductal prostate cancer underwent prostatectomy. Laser microdissection was used to separately isolate acinar and ductal foci. DNA and RNA were extracted, and used for integrative genomic and transcriptomic analyses.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Single nucleotide mutations, small indels, copy number estimates, and expression profiles were identified. Phylogenetic relationships between coincident foci were determined, and characteristics distinguishing ductal from acinar foci were identified.

RESULTS AND LIMITATIONS

Exome sequencing, copy number estimates, and fusion genes demonstrated coincident ductal and acinar adenocarcinoma diverged from a common progenitor, yet they harbored distinct alterations unique to each focus. AR expression and activity were similar in both histologies. Nine of 10 cases had mutually exclusive CTNNB1 hotspot mutations or phosphatase and tensin homolog (PTEN) alterations in the ductal component, and these were absent in the acinar foci. These alterations were associated with changes in expression in WNT- and PI3K-pathway genes.

CONCLUSIONS

Coincident ductal and acinar histologies typically are clonally related and thus arise from the same cell of origin. Ductal foci are enriched for cases with either a CTNNB1 hotspot mutation or a PTEN alteration, and are associated with WNT- or PI3K-pathway activation. These alterations are mutually exclusive and may represent distinct subtypes.

PATIENT SUMMARY

The aggressive subtype ductal adenocarcinoma is closely related to conventional acinar prostate cancer. Ductal foci contain additional alterations, however, leading to frequent activation of two targetable pathways.

Ductal Adenocarcinoma of the Prostate With a Rare Clinical Presentation; Late Gastric Metastasis

A 67 year male had robotic prostatectomy whose pathology revealed mixed type prostate cancer composed of 55% ductal and 45% acinar components. The patient was then admitted to hospital with sudden health problems including ascites and serious vomiting attacks in the 46th month after prostatectomy and the PSA test was 4565 ng/mL. Gastroscopic biopsy was reported and proved immunhistochemically undifferentiated ductal prostate cancer metastasis. This is the first report of late gastric metastasis of ductal prostate cancer.