The success of neoadjuvant immunotherapy trials like Niagara and those with EV-Pembro means most patients will receive immune therapy before surgery. This fundamentally shifts the clinical landscape, making the question of starting adjuvant immunotherapy less relevant as perioperative treatment becomes the standard.

In neoadjuvant settings, ctDNA monitoring allows for real-time therapy adjustment. Data from the iSpy platform shows 80% of hormone-positive patients clear ctDNA with half the chemotherapy, enabling de-escalation, while the remaining 20% can be identified for escalated treatment.

In patients achieving a complete response on EV-pembrolizumab, leading oncologists are using circulating tumor DNA (ctDNA) clearance in clinical practice to increase confidence and facilitate shared decision-making around stopping treatment, despite it not being standard of care.

The INVIGOR-11 trial data should be applied carefully. A positive ctDNA result post-surgery indicates when to *initiate* adjuvant immunotherapy. However, if a patient on neoadjuvant therapy becomes ctDNA-negative, this signals treatment efficacy and is a reason to *continue* the planned course, not a justification for stopping it early.

While promising, current ctDNA technology is not robust enough to justify stopping effective neoadjuvant systemic therapy in bladder cancer, even if a patient becomes ctDNA negative. Experts argue against using it to de-escalate treatment outside of a clinical trial due to the risk of undertreating a lethal disease.

While adjuvant immunotherapy benefits ctDNA-positive patients, it may not be the optimal strategy. Given their near-certainty of relapse (95%), using a single-agent immunotherapy when a more potent combination like EV-Pembro exists for metastatic disease raises the critical question of whether these high-risk patients are being undertreated.

In neoadjuvant breast cancer treatment, patients with residual cancer post-therapy remain at high risk of recurrence (10-20%) even if their ctDNA tests are negative. This finding suggests that the physical presence of residual disease is a critical factor, and ctDNA status alone cannot justify forgoing additional adjuvant therapy in this cohort.

The interpretation of ctDNA is context-dependent. Unlike in the adjuvant setting, in the neoadjuvant setting, remaining ctDNA positive post-treatment signifies that the current therapy has failed. These high-risk patients need a different therapeutic approach, not an extension of the ineffective one.

While a positive ctDNA test clearly signals the need for adjuvant therapy, a negative result is less actionable for deciding initial treatment. The key prognostic value comes from being *serially* undetectable over time, information that is not available when the immediate post-surgery treatment decision must be made.