Standard RECIST criteria can misclassify a significant response as "stable disease." A desmoid tumor can shrink dramatically in volume (from a "softball" to a "pencil") but maintain its length, showing no change by RECIST. This suggests clinicians are likely underestimating the true benefit of therapies.

A patient with a large, 12cm symptomatic desmoid tumor experienced significant spontaneous regression to 3cm while on active surveillance. This challenges the common assumption that only small tumors shrink on their own, highlighting the disease's unpredictability even in severe cases.

Even when desmoid tumor patients seem to tolerate niragacestat well, they often report a surprising improvement in well-being after discontinuing the drug. This reveals a subtle, cumulative quality-of-life impact from low-grade toxicities that may not be fully appreciated by patients or clinicians during active treatment.

Desmoid tumors exhibit highly variable behavior, acting as a chronic disease in some patients while being manageable in others. This necessitates a personalized, long-term treatment strategy rather than a standard protocol, often requiring a diverse armamentarium of therapeutic options to be used over a patient's lifetime as needs change.

While new systemic treatments for desmoid tumors can effectively control the disease and improve quality of life by managing symptoms, they introduce their own set of side effects. This creates a clinical challenge where the positive impact on the tumor must be carefully weighed against the negative impact of the treatment itself on the patient's daily life.

The standard of care for desmoid tumors has shifted away from upfront surgery due to high recurrence rates and poor patient outcomes. Experts now recommend systemic or other local therapies first, reserving surgery only for emergencies or after careful multidisciplinary team review.

Following cryoablation, imaging of a desmoid tumor may show a paradoxical increase in size. This is often a temporary inflammatory response, not disease progression. In one case, initial swelling was followed by symptom improvement and eventual tumor shrinkage, a key finding for interpreting post-procedure scans.

Surgical resection of desmoid tumors is now discouraged due to the risk of multifocal recurrence. A case demonstrated a patient developing multiple tumors throughout her leg 10 years after an initial surgery, illustrating how the tumor's finger-like growth can lead to widespread seeding if disturbed.

Patients on niragacestat for desmoid tumors often experience rapid symptom improvement. However, this clinical benefit significantly precedes radiological response (tumor shrinkage on scans), which can take over five months to appear. This disconnect is crucial for managing patient expectations and assessing early treatment efficacy.