WGS ctDNA Monitoring Improves Adjuvant Treatment Decisions in Cancer

Cardiff University Study Evaluates Signatera Genome in Solid Tumors

A retrospective pan-cancer analysis published in The Oncologist demonstrates that whole-genome sequencing-based circulating tumor DNA monitoring can detect molecular residual disease and potentially inform adjuvant treatment decisions. Kefah Mokbel highlighted the findings on LinkedIn, pointing to the clinical potential of the Signatera Genome assay across five solid tumor types.

The study examined 386 patients and 2,674 plasma samples. Researchers evaluated breast cancer, non-small cell lung cancer, colorectal cancer, melanoma, and renal cell carcinoma to determine how molecular residual disease tracking relates to systemic recurrence-free survival.

Prognostic Value of Molecular Residual Disease Testing

Detection of molecular residual disease within three months following surgery showed strong prognostic value. Patients with detectable circulating tumor DNA faced significantly worse systemic distant recurrence-free survival, with a hazard ratio of 23.7.

During post-treatment surveillance, molecular residual disease positivity was even more strongly associated with systemic recurrence, registering a hazard ratio of 104.7. The assay achieved greater than 90% sensitivity and 100% specificity for systemic recurrence in longitudinal monitoring, with 62% of positive patients showing circulating tumor DNA levels below 100 parts per million.

Adjuvant Treatment Outcomes and De-Escalation Potential

Among patients who tested positive for molecular residual disease, 12-month systemic distant recurrence-free survival reached 67.1% for those who received adjuvant treatment, compared to 33.3% for untreated patients. This difference amounted to 33.8 percentage points. Median systemic distant recurrence-free survival was also longer in treated patients at 34.6 months, compared to 8.8 months for untreated patients, though small patient numbers left this specific difference outside statistical significance.

Patients who tested negative for molecular residual disease showed no clear systemic distant recurrence-free survival benefit from adjuvant therapy. This finding suggests that molecular risk stratification could eventually help identify patients who can safely avoid unnecessary treatment.

Prospective Trials Required Before Clinical Implementation

The study’s retrospective design, small treatment subgroups, and non-randomized treatment decisions mean that prospective clinical trials are necessary before molecular residual disease status can guide treatment escalation or de-escalation in routine practice. While the results support moving away from relying solely on clinicopathological risk factors toward tailoring adjuvant therapy according to molecular evidence, researchers emphasize that clinical validation must precede changes to standard care pathways.

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