Background. Assessment of adjustment of patients in cancer treatment trials is becoming more
common and increasingly regarded as a useful outcome measure. The widely used Mental
Adjustment to Cancer (MAC) Scale was designed to measure Fighting Spirit (FS), Anxious
Preoccupation (AP), Helpless–hopelessness (HH) and Fatalism.
Methods. Questionnaire responses from 632 breast cancer patients were randomly divided into two
groups, one for exploratory analyses and possible scale refinement, and the other for validation
Results. Estimates of reliability (Cronbach's α) were satisfactory for two scales, FS (α = 0·85) and
HH (α = 0·81), but lower for AP (α = 0·65) and Fatalism (α = 0·64). Exploratory factor analysis
suggested that the MAC Scale might be measuring six independent constructs including two related
to Fighting Spirit (Positive Orientation to the Illness, Minimizing the Illness), two related to
Fatalism (Fatalism-revised, Loss of Control), a construct we have named Angst, and an unchanged
HH construct. Scales developed to measure these constructs were satisfactorily replicated in
confirmatory analyses but some reliabilities were lower than desirable. The general structure of the
MAC Scale remained little changed despite the division of two scales and the suggested removal of
six items. The refined scales correlated with the Hospital Anxiety and Depression scale and the
Medical Coping Modes Questionnaire, indicating good concurrent validity.
Conclusions. While reasonable reliability of the original scales persists through analyses of the
MAC Scale, the original factor structure could not be reproduced. Six refined constructs with strong
construct validity were identified within the overall domain of mental adjustment to cancer.