Blood Test for Tumor DNA Predicts Survival After Cancer Treatment Before Surgery

A simple blood draw may soon tell oncologists which cancer patients are truly benefiting from the drug and radiation regimens they receive before surgery, according to one of the most comprehensive analyses of liquid biopsy evidence published to date. A team of researchers at West China Hospital of Sichuan University has pooled data from 41 studies covering 3,058 patients with solid tumors and found that the mere presence of circulating tumor DNA, or ctDNA, in the bloodstream after neoadjuvant therapy is one of the strongest predictors of poor survival ever measured in oncology. Patients in whom tumor DNA could still be detected faced dramatically higher risks of relapse and death than those whose blood came back clean, with hazard ratios reaching as high as 8.6 for disease-free or relapse-free survival.

Neoadjuvant therapy, the treatment given before a tumor is surgically removed, has become a cornerstone of modern cancer care. In rectal, breast, esophageal, lung, and many other cancers, shrinking the tumor with chemotherapy, radiotherapy, or immunotherapy before the operation can make surgery easier, improve outcomes, and in some cases allow less aggressive procedures. Yet clinicians have long struggled with a fundamental uncertainty: after the treatment course ends, they cannot reliably know whether microscopic disease remains in the body. Imaging is too coarse to see residual cancer cells, and pathological examination of the resected specimen only becomes available after surgery, when the treatment window has already closed. This is precisely the gap that ctDNA promises to fill.

Circulating tumor DNA consists of small fragments of genetic material shed by cancer cells into the bloodstream as they die or actively release DNA. These fragments carry the same mutations that define the original tumor, which means that highly sensitive sequencing or digital PCR assays can distinguish them from the vast background of normal cell-free DNA released by healthy tissues. When a tumor responds completely to treatment, ctDNA levels typically fall below the limit of detection. When resistant clones survive, they continue to shed DNA, and a blood test can pick up that molecular signal long before any relapse becomes visible on a scan. The concept, often called a liquid biopsy, has already transformed follow-up care in colorectal cancer, and the new meta-analysis suggests its power extends across the entire spectrum of solid tumors treated before surgery.

The research team, led by Tao Jin and Ershuo Du with Kun Yang as corresponding author, systematically searched PubMed, Embase, and the Cochrane Library from database inception through October 2024. Two reviewers independently screened studies, extracted data, and graded methodological quality using the Newcastle-Ottawa Scale for cohort studies, the Cochrane Risk of Bias 2.0 tool for randomized trials, and ROBINS-I for non-randomized interventional studies. They used Stata 17.0 to pool hazard ratios for four survival endpoints: disease-free or relapse-free survival, overall survival, progression-free survival, and event-free survival. Publication bias was assessed with Begg’s test and funnel plots, and sensitivity analyses confirmed the robustness of the pooled estimates.

The headline numbers are striking. Patients with detectable ctDNA after neoadjuvant therapy had a hazard ratio of 8.60 for worse disease-free or relapse-free survival, meaning their risk of relapse or death was more than eight times higher than patients with negative tests. For overall survival the pooled hazard ratio was 7.00, for progression-free survival 3.85, and for event-free survival 3.40. In clinical terms, a positive ctDNA result after preoperative treatment behaves less like a modest risk modifier and more like a categorical dividing line between two very different disease trajectories. Few biomarkers in oncology, whether imaging-based, pathological, or molecular, achieve effect sizes of this magnitude.

The subgroup analyses reveal how consistently this signal holds across tumor types. In rectal cancer, positive ctDNA conferred a hazard ratio of 9.23 for disease-free or relapse-free survival and 9.72 for overall survival, a critical finding given the intense current interest in organ preservation strategies for rectal cancer, where clinicians weigh whether surgery can be safely omitted in patients who respond completely to chemoradiation. In urothelial cancer the association was even stronger, with hazard ratios of 27.92 for disease-free or relapse-free survival and 21.29 for overall survival. Esophageal cancer showed a disease-free survival hazard ratio of 10.83, while lung cancer patients with detectable ctDNA faced a 25-fold higher hazard of death. Breast cancer, pancreatic cancer, and colorectal liver metastases all showed significant associations as well, with hazard ratios ranging from roughly 3.6 to 11.7 depending on the endpoint.

The picture is not uniformly clear-cut, however, and the authors are careful to note that prognostic performance varies by tumor type and clinical context. In melanoma, the association between ctDNA detection and disease-free or relapse-free survival did not reach statistical significance, with a confidence interval crossing unity. In gastric cancer, ctDNA positivity predicted worse event-free survival with a hazard ratio of 3.00, but the overall survival association fell just short of significance. Ovarian cancer likewise showed a non-significant trend for overall survival. These exceptions likely reflect tumor biology, since melanoma and ovarian cancer shed DNA differently and often present with lower or more heterogeneous ctDNA fractions, as well as the smaller number of studies available for these subgroups.

Perhaps the most clinically important finding is that the signal survived every stratification the team applied. Whether studies were prospective or retrospective, whether blood was drawn before surgery or during follow-up, whether patients received immunotherapy or conventional regimens, whether ctDNA was measured by next-generation sequencing or droplet digital PCR, and whether the reported statistics came from univariate or multivariate models, positive ctDNA status consistently predicted worse outcomes on all four survival endpoints. This robustness matters because multivariate adjustment, in particular, demonstrates that ctDNA adds prognostic information beyond established clinical factors such as stage, grade, and pathological response. The consistency across detection platforms also suggests the finding is not an artifact of any single laboratory technology.

The implications for trial design and clinical practice are considerable. In rectal cancer, several ongoing trials are already using ctDNA clearance to select patients for a watch-and-wait approach instead of radical surgery, and this meta-analysis provides the strongest quantitative backing yet for that strategy. In breast and esophageal cancer, a positive post-treatment ctDNA result could identify patients who need escalation, such as additional chemotherapy, extended immunotherapy, or more aggressive surgery, while a negative result might safely allow de-escalation, sparing patients the toxicities of overtreatment. Because the test requires only a blood sample, it can be repeated at multiple time points, opening the door to real-time monitoring of treatment response rather than a single static assessment.

Challenges remain before ctDNA-guided decisions become standard of care. The included studies varied in assay sensitivity, timing of blood draws, and mutation panels, and most evidence is observational, so prospective randomized trials are still needed to prove that acting on ctDNA results actually improves survival rather than merely predicting it. The authors also note that the exceptional hazard ratios seen in some tumor types come from smaller subgroups with wide confidence intervals, and that heterogeneity across studies warrants cautious interpretation. Nevertheless, with 41 studies and more than 3,000 patients converging on the same conclusion, the evidence now strongly supports ctDNA as a prognostic biomarker for patients undergoing neoadjuvant therapy. What was once an experimental research tool is moving decisively toward the clinic, where a routine blood test could help decide, within days, whether the treatment a patient just endured has truly eradicated their cancer or whether invisible disease still lurks and demands a different plan.

Subject of Research: Prognostic value of circulating tumor DNA in solid tumor patients receiving neoadjuvant therapy

Article Title: Association between circulating tumor DNA and the prognosis of solid tumor patients receiving neoadjuvant therapy: a meta-analysis

Article References: Jin, T., Du, E., Fu, X., Cao, Y., Liang, P., Gou, Y., & Yang, K. (2026). Association between circulating tumor DNA and the prognosis of solid tumor patients receiving neoadjuvant therapy: a meta-analysis. BMC Cancer. https://doi.org/10.1186/s12885-026-16983-3

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16983-3

Keywords: circulating tumor DNA, liquid biopsy, neoadjuvant therapy, meta-analysis, prognosis, solid tumors, biomarker, disease-free survival, overall survival, rectal cancer, breast cancer, precision oncology