Measuring the impact of cancer: a comparison of non-Hodgkin lymphoma and breast cancer survivors

Self-report instruments such as the Impact of Cancer (IOC) are designed to measure quality of life (QOL) impacts that cancer survivors attribute to their cancer experience. Generalizability of QOL findings across distinct diagnostic categories of survivors is untested. We compare measurement of the impact of cancer using the IOC instrument in breast cancer (BC) survivors (n = 1,188) and non-Hodgkin lymphoma (NHL) survivors (n = 652). A registry-based sample of NHL survivors completed the IOC questionnaire and the FACT-G, FACT-LYM, Medical Outcomes Study (MOS) SF-36, Post-Traumatic Stress Disorder Checklist-Civilian Version, Post-Traumatic Growth Inventory and MOS Social Support scales. IOC responses of the NHL survivors were subjected to de novo scaling to identify impact domains for comparison to IOC version 2 (IOCv2) domains, which were previously developed based on BC survivor responses. Concurrent validity was assessed by correlating the IOCv2 scales with the other measures. IOCv2 scores were compared between the BC and NHL survivor samples. The BC and NHL survivors exhibited similar impact domains and had factor structures that were largely congruent. The concurrent validity analysis revealed patterns of association that supported the interpretation and validity of the IOCv2 scales. Differences in IOCv2 scores between the BC and NHL groups suggested differential impacts in distinct survivor groups that could be detected using the IOCv2. The results suggest that the IOCv2 measures common and important survivor concerns and support its generalizability to the broader long-term cancer survivor population. Instruments such as the IOCv2 can provide valid assessment of QOL impacts in long-term cancer survivors, facilitating the characterization of these impacts and development of appropriate interventions