Watch and wait policy in advanced neuroendocrine tumors: What does it mean?

Neuroendocrine neoplasms (NENs) are a group of rare and heterogeneous malignancies, which can develop in various organs. The clinical course of NENs is quite heterogeneous, with different spontaneous growth rates after diagnosis, and different degrees of sensitivity to the same therapy even when they have similar characteristics. Watch and wait (W and W), is a term coined to indicate observation being conducted to assess the evolution of the tumor without administering any anti-tumor therapy. It has been applied to NENs since in extremely rare cases they tend to remain stable for a long time. Although W and W has been reported in several guidelines and recommendations it has never been validated, nor has it been specifically investigated. Furthermore it is not standardized. Therefore its application in clinical practice can differ in terms of tumor status assessment, type and timing of imaging or other exams utilized. In conclusion, while undertaking W and W to delay the first-line therapy by some weeks may be justified in good performance asymptomatic patients with low-grade NENs in order to usefully characterize the disease and patient and thereby choose the best therapy and therapeutic strategy, it seems to be far more difficult to justify W and W with the intent of avoiding an anti-tumor treatment. It should be considered that not only do NENs tend to grow even when they have very favorable biological characteristics but also that the alternative to W and W is most commonly a low toxic and effective treatment with somatostatin analogs.