CONTEXT AND CAVEATS
Cancer diagnosis, treatment, and survival can engender lingering quality of life concerns.
Data from 1188 breast cancer survivors 5–10 years after diagnosis were used to develop and validate a questionnaire, the Impact of Cancer version 2 (IOCv2).
Patterns of association between IOCv2 scale scores and demographic, medical, and treatment characteristics of the breast cancer survivors indicated good construct validity.
The IOCv2 is a validated tool for measuring the impact of cancer on the quality of life of long-term cancer survivors.
Only data from breast cancer survivors were used and so IOCv2 has not been validated for survivors of other types of cancer. Most of the 1188 breast cancer survivors were white and none were more than 10 years away from their breast cancer diagnosis and so the data may not be fully representative of the population of all breast cancer survivors.
From the Editors
There were approximately 10.8 million cancer survivors in the United States as of January 2004, including 6.8 million who had survived more than 5 years since diagnosis (1
). The size of the survivor population has increased each year since 1975 (1
) and can be expected to continue on an upward trend because of improvements in early detection and treatment as well as expanding numbers of incident cases of cancer associated with aging of the population.
A number of studies (2
) have shown that long-term cancer survivors have fairly high levels of functioning on generic measures of health-related quality of life. However, a large literature indicates that the experiences of cancer diagnosis, treatment, and survival can engender lingering problems and concerns across physical, psychological, social, and spiritual domains. Examples of disruptions reported for adult cancer survivors include fatigue (5
), body image concerns (7
), sexual health and functioning concerns (7
), fear of recurrence (11
), stress syndromes (12
), and financial issues (7
), as well as distress, anxiety, and depression (8
). The experience of long-term survivorship can include positive life changes as well, such as personal growth (18
), an increased sense of meaning or purpose (12
), and positive effects on relationships (10
). Impacts are further documented in several recent reviews of the quality of life of cancer survivors (22
Many concerns of long-term survivors are distinctive of or unique to the long-term cancer survivor experience and are not necessarily captured by generic instruments that assess health-related quality of life. This circumstance creates a need for tools that specifically measure this multidimensional impact. Such instruments are needed to support the national research effort into the late effects of cancer and to develop and deliver effective interventions and supportive care to improve outcomes.
Several instruments have been developed to assess the concerns of long-term cancer survivors specifically. Some of these instruments are broad-based scales measuring health-related quality of life that have been applied to long-term survivorship. An early instrument that assesses health-related quality of life with this broad view is the Quality of Life-Cancer Survivors (QOL-CS) scale (27
). The QOL-CS scale was conceptualized as measuring quality of life in the following four domains: Physical Well-Being, Psychological Well-Being, Social Well-Being, and Spiritual Well-Being. This instrument was adapted from other health-related quality of life instruments and is composed predominantly of generic items. The few cancer-specific items address distress associated with diagnosis and treatment and fear of recurrence and are not formulated as separate scales. Another instrument, the Long-Term Quality of Life scale (28
), measures four broad domains, Somatic Concerns, Spiritual/Philosophical View of Life, Fitness, and Social Support, which are not necessarily distinct from generic health-related quality of life concepts or specifically attributable to the cancer experience. This instrument is designed for female cancer survivors only. The Quality of Life in Adult Cancer Survivors (QLACS) scale (29
) is a more recent instrument that takes a deliberately broad view of quality of life domains that are relevant to long-term cancer survivors. The instrument consists of five cancer-specific domains (Financial Problems, Benefits, Distress-Family, Appearance, and Distress-Recurrence) and seven generic domains (Negative Feelings, Positive Feelings, Cognitive Problems, Pain, Sexual Interest, Energy and Fatigue, Sexual Function, and Social Avoidance). Narrow construct-specific instruments for cancer survivors have also been developed. For example, there are several scales measuring fear of cancer recurrence, as reviewed previously (31
). The Assessment of Survivor Concerns, a five-item questionnaire (32
), is an example of such a scale. Construct-specific scales are generally designed to serve as adjuncts to, or modules in, other health-related quality of life measures.
In contrast to both the more broadly focused instruments to assess health-related quality of life and the narrow construct-specific measures, the Impact of Cancer (IOC) scale (33
) was developed specifically to measure unique and multidimensional aspects of long-term cancer survivorship that are not measured by existing tools. This instrument focuses almost exclusively on problems, issues, and changes that long-term survivors ascribe to their cancer experience. The development of content and initial scaling (ie, identification and formation of multi-item scales to measure psychosocial domains), of the IOC have been described previously (33
). The item-generation process used several strategies to capture a broad range of long-term cancer survivor experiences. The process began with semistructured qualitative interviews with 47 long-term survivors of one of four cancers (breast, colorectal, prostate, or lymphatic cancers) representing four age groups (18–30, 31–45, 46–65, or ≥66 years). The survivors were asked to describe how cancer had affected them in physical, psychological, social, and spiritual areas of life. The concerns expressed in the interviews were extracted and coded, with the goal of representing the breadth of experiences, regardless of frequency. These codes were used to develop a pool of 325 potential items. This pool was examined for redundancy, comprehensibility, and coverage of long-term cancer survivor issues by an expert panel and by two focus groups of long-term cancer survivors. A resultant pool of 125 items was then pilot tested in face-to-face interviews with 13 long-term cancer survivors. Ultimately, 81 potential scale items reflecting a broad range of survivor concerns were selected.
To conduct an initial scaling the 81-item questionnaire was administered to 193 long-term survivors of breast, prostate, colorectal, or lymphatic cancers. The small size of this group required an analytic strategy of conducting factor analysis by use of a priori domains. These analyses resulted in the identification of 10 subscales—Health Awareness, Body Changes, Positive Self-Evaluation, Negative Self-Evaluation, Positive Outlook, Negative Outlook, Life Interferences, Value of Relationships, Meaning of Cancer, and Health Worry—that were measured by 41 items (33
). Development of scales for employment and relationship items could not be conducted because of the small number of respondents to whom these items applied.
When the IOC was developed, it was recognized that the initial scaling was part of a continuing process of instrument development. In particular, further evaluation and refinement of the scale in larger groups of long-term cancer survivors was needed. This article describes the refinement, reformulation, and validation of the IOC scale by use of responses from a group of 1188 disease-free long-term survivors of breast cancer. To ensure that the final scale would cover a comprehensive set of survivor concerns, we used the full 81-item pool as the basis for de novo scaling. Through a process of factor analysis, cross-validation, and psychometric evaluation, we developed a revised instrument, the IOC version 2 (IOCv2). This instrument is designed to measure impacts of cancer in long-term survivors that are not captured by other instruments and to be suitable for widespread use in investigations of the well-being of this burgeoning population.