Baseline tumor lesions are divided into measurable lesions and non-measurable lesions.

1. Measurable Lesions
(1) Lesions with at least one measurable diameter.
(2) According to CT or MRI evaluation, the longest diameter of lesions must be at least 10 mm (2 slices, slice thickness 5-8 mm).
(3) According to chest X-ray evaluation, the longest diameter of lesions must be at least 20 mm.
(4) According to caliper evaluation, superficial lesions with a longest diameter ≥10 mm.
(5) Malignant lymph nodes: pathologically enlarged and measurable, single lymph node short diameter on CT scan must be ≥15 mm (CT scan slice thickness recommended to be no more than 5 mm). Only the short diameter is measured in baseline and follow-up.

Note: For malignant tumor lymph nodes, the shortest axis is used as the diameter, while for other measurable lesions, the longest axis is used.

2. Non-measurable Lesions
(1) Non-measurable lesions include small lesions (including lymph nodes with short axes between 10-14.9 mm) and truly unmeasurable lesions, such as pleural or pericardial effusion, ascites, inflammatory breast disease, leptomeningeal disease, lymphangitis involving skin or lungs, clinically evident masses that cannot be accurately measured with calipers, and abdominal masses found on physical examination that cannot be measured with repeated imaging techniques.
(2) Bone disease: bone disease is considered non-measurable, except that soft tissue components may be evaluated using CT or MRI, if they meet the definition for evaluation at baseline.
(3) Previous local treatment: previous radiation lesions (or other locally treated lesions) are considered non-measurable lesions, unless there is progression after treatment completion.

3. Normal Sites
(1) Cystic lesions: simple cysts should not be considered malignant lesions and should not be recorded as target or non-target lesions. Cystic lesions thought to be cystic metastases are measurable lesions if they meet the specific definitions mentioned above. If non-cystic lesions are also present, those lesions should be prioritized as target lesions.
(2) Normal nodules: nodules with a short axis <10 mm are considered normal and should not be recorded or classified under measurable or non-measurable lesions.

All disease sites must be evaluated at baseline. The baseline evaluation should be conducted as close to the start of the trial as possible. For sufficient baseline evaluation, all required scans must be performed within 28 days prior to treatment, and all diseases must be accurately recorded. If the baseline evaluation is insufficient, the subsequent status is usually uncertain.

1. Target Lesions
All involved organs can have up to 2 lesions per organ, totaling 5 lesions; all measurable lesions should be considered as baseline target lesions. Target lesions should be selected for accurate and repeatable measurement based on size (longest lesion) and suitability. Record the longest diameter of each lesion; pathological lymph nodes should record the short axis. The total diameter of all target lesions at baseline (longest diameter for non-nodular lesions, shortest axis for nodular lesions) serves as the basis for evaluative comparisons made during the trial.
(1) If two lesions merge, measure the merged mass. If target lesions split, use the sum of each part.
(2) For lesions with different diameters, select the most measurable lesions as target lesions.

2. Non-target Lesions
Non-target lesions refer to lesions that are not measured or listed as target lesions. The evaluation is based on the existence of lesions, with response classifications of disease progression, stable disease, and no evidence of disease. The evaluation of non-target lesions is not included in the calculation of the overall response. However, the sum of the diameters of non-target lesions can be evaluated if no new lesions appear; if new lesions appear, the status must be classified as disease progression.

3. New Lesions
The emergence of new lesions represents disease progression; there is no need to measure or classify new lesions. If new lesions are discovered, any existing target or non-target lesions must also be assessed; if the overall tumor burden increases, then the status is classified as disease progression.

The following response evaluations are based on the criteria set for measurable lesions and non-measurable lesions. The types of assessments include the following:

1. Complete Response (CR)
All target lesions disappear, and all pathological lymph nodes must have a short diameter reduced to <10 mm.

2. Partial Response (PR)
The sum of the diameters of target lesions must decrease by at least 30% compared to baseline.

3. Stable Disease (SD)
The degree of shrinkage of target lesions has not reached PR, and the degree of increase has not reached PD, falling between the two.

4. Progressive Disease (PD)
The diameter must increase by at least 20% (baseline measurement is the reference if it is the minimum); in addition, there must be an absolute increase of at least 5 mm in the sum of diameters (the appearance of one or more new lesions is also considered disease progression).