Social anxiety disorder is one of the most popular psychiatric disorders in the general population and is also well known as a very common comorbid psychiatric disorder among patients with major depression. On the other hand, social anxiety disorder has been termed “the neglected anxiety disorder” because its diagnosis is often missed. Furthermore, the potential impact of social anxiety disorder on the psychological distress of cancer patients has not been reported.

We encountered two cancer patients with refractory depression after cancer diagnosis, in whom comorbid social anxiety disorder was unexpectedly detected during a subsequent follow-up.

To the best of our knowledge, this is the first report to discuss the potential impact of social anxiety disorder on cancer patients' distress. These two cases may help to improve our understanding of the complicated mental health problems of cancer patients and the potential influence of social anxiety disorder on patients' follow-up medical treatment.

Comorbid social anxiety disorder should be considered when a cancer patient's depression is resistant to treatment and the existence of communication problems between the patient and the medical staff is suspected.