Additional reviews  have continued to find adjustment disorders to be the most common mental disorder. In patients with advanced cancer, prevalence ranges from 14% to 34.7%; in terminally ill patients, rates range from 10.6% to 16.3%. These variable prevalence rates are influenced by stage of disease, type of cancer, diagnostic procedures used, and other patient variables. In a study of women with breast cancer undergoing adjuvant chemotherapy, a 36.1% prevalence rate was found.
In another study of terminally ill Japanese cancer patients referred to a palliative care unit, 16.3% were diagnosed with an adjustment disorder at the time of their initial referral, and 10.6% were diagnosed with an adjustment disorder at the time of their admission to the palliative care unit. Of patients diagnosed with adjustment disorder at initial referral, 42% had progressed to major depression at admission to the unit, and 42% had no diagnosis.
Thus, it seems safe to conclude that the adjustment disorders are the most commonly diagnosed mental disorder in the oncology setting.
As defined in the diagnostic criteria, an adjustment disorder begins within 3 months of the onset of an identifiable stressor and lasts no longer than 6 months after the stressor or its consequences have ceased. Two specifiers exist to discriminate between an acute adjustment disorder (<6 months) and a chronic adjustment disorder (>6 months). The cancer patient may experience a sequence of multiple, sequential stressors such as the diagnosis, the start of treatment, side effects of treatment, conclusion of treatment, and return to work.
It is often difficult to determine when a stressor has ceased. It is not unusual to see a chronic adjustment disorder that persists because of the presence of multiple, sequential stressors. The persistent adjustment disorder may also progress to become a more serious mental disorder (e.g., major depressive disorder). Chronic adjustment disorders that persist and progress to more severe mental disorders appear more common in children and adolescents than in adults. (Refer to the PDQ summary on Pediatric Supportive Care for more information.)
Problems in Diagnosing Adjustment Disorders
The adjustment disorders are an intermediate category between normal adjustment and a specific diagnosable mental disorder. In terms of their location within a hierarchy of increasingly severe mental disorders, the adjustment disorders are an intermediate category as follows:
- Major mental disorders (e.g., major depressive disorder, panic disorder, posttraumatic stress disorder, generalized anxiety disorder).
- Disorders not otherwise specified.
- Adjustment disorders.
- Problem-level diagnoses (e.g., partner relational problems, bereavement, physical abuse of child).
- Fluctuations in mood that represent normal adaptation.
Screening instruments for the identification of adjustment disorder have been difficult to identify.[7,8] This intermediate status and the lack of any specific list of symptoms raise a number of problems with the adjustment disorder's diagnostic category. Most of the problems stem from lack of specificity and resulting subjectivity. This lack of specificity applies to both the identifiable stressor and the marked distress/significant impairment.