Comparing nodal versus bony metastatic spread using tumour phylogenies

Area of Science:

• Oncology
• Genomics
• Cancer Metastasis Research

Background:

• The precise role of lymph node metastases in prostate cancer progression and mortality remains unclear.
• Patients with lymph node-only metastases exhibit better prognoses than those with distant spread, hinting at different origins.
• Understanding metastatic pathways is crucial for improving prostate cancer treatment strategies.

Purpose of the Study:

• To investigate the developmental origins of lymph node versus osseous (bone) metastases in prostate cancer.
• To compare the evolutionary trajectories of primary tumors leading to different metastatic sites.
• To determine if lymph node metastases serve as a precursor to distant osseous metastases.

Main Methods:

• Genome-wide copy-number profiling was employed to analyze 48 tumor samples from 6 prostate cancer patients.
• Phylogenetic analysis was used to reconstruct tumor evolutionary patterns.
• Comparison of metastatic cell origins in patients with lymph node-only versus osseous metastases.

Main Results:

• Metastatic cells within regional lymph nodes were traced to evolutionarily advanced extraprostatic tumor cells.
• Osseous metastases demonstrated a less constrained origin, arising from both intra- and extraprostatic tumor cells at various evolutionary stages.
• No evidence suggests lymph node metastases are an intermediate step for osseous metastasis development.

Conclusions:

• Prostate cancer lymph node metastases represent a distinct metastatic lineage, originating from advanced tumor clones.
• Osseous metastases arise through broader and potentially earlier dissemination pathways.
• These findings challenge the model of lymph node metastases as a necessary intermediate in prostate cancer distant spread.