Question 1

Which lesions should be selected as target lesions?

Accepted Answer

Select the largest and most reliably measurable lesions. They should be ≥10 mm long diameter (CT) or ≥15 mm short axis (lymph nodes). Avoid selecting lesions in previously irradiated fields.

Question 2

How do I confirm complete response?

Accepted Answer

CR requires confirmatory imaging at ≥4 weeks. PR and PD also require confirmation at ≥4 weeks in non-randomised trials. SD requires ≥6–8 weeks of stability from baseline.

Question 3

How does RECIST 1.1 handle lymph nodes?

Accepted Answer

Lymph nodes are measured in short axis. A node with short axis <10 mm is considered normal. Nodes 10–15 mm are target lesions. Nodes >15 mm are measurable target lesions.

Question 4

What are the limitations of RECIST?

Accepted Answer

RECIST does not capture tumour biology (metabolic activity, growth kinetics). It underestimates response in immunotherapies where pseudoprogression occurs. iRECIST (immune RECIST) addresses this.