2855 - How Do Oncologists Globally Define Oligometastatic Disease? A Cross-Sectional Survey Study

Purpose/Objective(s):

To evaluate how oncologists across different regions globally define oligometastatic disease (OMD) and to identify patterns or discrepancies in diagnostic criteria, lesion cutoffs, and treatment intent.

Materials/Methods:

A cross-sectional, anonymous online questionnaire was distributed to practicing oncologists globally. The survey assessed definitions of OMD, classification by timing, imaging preferences, case-based scenarios interpretation, and management strategies. Data was reported as frequencies and percentages and analyzed using descriptive statistics.

Results:

This ongoing pilot study (N=31) collected data through an online survey completed by 31 respondents from various institutes worldwide. The questionnaire was created using Google Forms and distributed via social media. Most respondents were Radiation Oncologists, 29% were Medical Oncologists, and the remainder were surgical and clinical oncologists. Among them, 19 (61.3%) had access to stereotactic radiotherapy.

17 (54.8%) defined oligometastatic disease (OMD) as 1–5 lesions, while others defined it as 1–3 lesions or had no fixed number. 22 respondents included non-regional lymph nodes in the definition of OMD. PET-CT was the preferred imaging modality for 19 (61.3%) participants, 4 (12.9%) preferred CT, and the rest selected imaging based on lesion site. 24 (77.4%) considered involvement of 2 or more than 2 organs as OMD. 19 (61.3%) classified OMD independent of time, whereas 15 (48.4%) defined synchronous OMD as metastasis detected at initial diagnosis.

In the NSCLC scenario, 25 (80.6%) classified the disease as oligometastatic and 5 (16.1%) as poly-metastatic; 28 (90.3%) favored MDT with ablative intent. In the prostate cancer scenario, 24 (77.4%) identified the state as oligo-progressive, while 7 classified it as OMD; 29 (93.5%) recommended SBRT. Most oncologists, 22 (71%), supported curative treatment of OMD, while 7 (22.6%) favored palliative intent. SBRT/SABR was the preferred local therapy among 20 (64.5%), 12 (38.7%) chose surgery, and others preferred site-based or tumor board–guided decisions. Regardless of SBRT access, most would treat OMD with curative intent (p = 0.301). Clinician specialty was significantly associated with inclusion of non-regional lymph nodes in OMD definition (p = 0.023) and willingness to offer metastasis-directed local therapy (p = 0.041).

Conclusion:

Oncologists differ greatly in their definitions, classifications, and approaches to oligometastatic disease management. These findings highlight the requirement of a universal consensus and underline the importance of standardized, evidence-based criteria to guide clinical practice and future trials.