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Working Group 4: Prevention, Risk Assessment, and Screening

Speakers:
Jeanne Mandelblatt, M.D., M.P.H., Lombardi Cancer Center
Lodovico Balducci, M.D., H. Lee Moffitt Cancer Center and Research Institute

Co-Chairs:
Jeanne Mandelblatt, M.D., M.P.H., Lombardi Cancer Center
Lodovico Balducci, M.D., H. Lee Moffitt Cancer Center and Research Institute

Introduction

Older persons have the highest incidence rates of almost all cancers but the lowest rates of receiving early detection tests of proven efficacy. Whether this is a paradox depends on one's perspective about whether older persons should be screened. Conflicting recommendations exist about upper age limits for screening because of a lack of randomized clinical trials data, enormous heterogeneity among older individuals, and uncertain biology of tumors in aged patients.

In their introductory presentations, Drs. Jeanne Mandelblatt and Lodovico Balducci discussed the demography and biology of aging and cancer and presented evidence on the effectiveness of primary prevention and early detection. Working Group 4 discussed the efficacy and cost-effectiveness of screening, screening research, barriers to screening, the goal of cancer prevention, and the use of chemoprevention techniques in older persons. In the final plenary session of the workshop, several participants cautioned that cancer centers do not offer the best infrastructures for conducting large-scale, population-based studies (e.g., on chemoprevention and lifestyle) that require considerable statistical power. Other research infrastructures, with the participation and leadership of cancer centers, would provide more suitable environments for such studies. This is discussed further in the section entitled Cancer Center Role.

Research Questions

  1. Do age biases in the health care system interfere with the delivery of effective, optimal prevention and early detection services?
  2. Should upper age or physiologic health limits be established for screening?
  3. What are the most appropriate endpoints for primary and secondary prevention in older individuals?
  4. What is the efficacy of screening in different age groups?
  5. Should screening be done for precursor lesions?
  6. Might aging-related changes, gene expression, and other factors, such as molecular markers, in young to middle-aged populations be predictive for malignancies whose progress could be prevented by noninvasive procedures?
  7. What system changes would serve as an incentive for physicians to routinely conduct cancer screening and risk assessment in older patients?

Cancer Center Role

Cancer centers can play a prominent role in conducting new screening, prevention, and risk assessment studies of cancer in the elderly. The expansion of knowledge emanating from the cancer centers in basic and clinical sciences should be extended to public health policy and community application in advocacy for access to cancer care and quality cancer care.

Although developing and organizing research networks across cancer center programs, other research institutions, community groups, and providers of care present a considerable challenge, efforts should be undertaken to promote public health goals in cancer screening, prevention, and chemoprevention in older persons. Cancer centers can serve an institutional leadership role by developing clinical oncology/geriatric service teams.

The research priorities of Working Group 4 provoked much discussion among participants in the final plenary session. Several workshop participants who were associated with cancer centers indicated that the large-scale screening and chemoprevention trials suggested in the priorities are not within the purview of cancer centers. Not only are these population-based trials lengthy, but they also require large samples and considerable funding. As one individual said, "These trials are done in people, not patients." Another participant added that, even if unlimited resources were available, cancer centers are unlikely to offer the numbers of research subjects needed to acquire sufficient power for the small effect differences likely to be noted.

Possibly, the cancer centers could conduct pilot studies to address issues such as adherence and recruitment. Cancer center linkage with the community should be encouraged but not necessarily for large-scale screening and chemoprevention trials. A few participants expressed support for the working group's research priorities, however, and gave examples of cancer centers that could achieve these goals, perhaps in certain parts of the country.

Research Priorities

Working Group 4 identified colorectal cancer as a malignant tumor on which little screening research has been done in older persons, who are at high risk for this particular malignancy.

  1. Develop and test interventions to decrease screening barriers. Colon and rectum cancers should receive high priority because of their associated morbidity and mortality in the elderly and the lack of prior research in this area.
    • Colon cancer ranks third in cancer mortality, after lung and prostate tumors for males, and after lung and breast tumors for females. Over 75 percent of colon cancer deaths and 72 percent of rectum cancer deaths are in individuals aged 65 years and older.
    • When a person is too old to benefit from screening is not clear, although the average 65-year-old has a life expectancy of about 18 years. Progression of a polyp to cancer takes 5–10 years. The highest age-specific incidence and mortality rates per 100,000 population for both males and females are in the age groups 80–84 years and 85 years and older.
  2. Conduct chemoprevention and lifestyle change trials to decrease dependency, deterioration in quality of life, and mortality. The effects of chemoprevention should be studied, beginning at different ages, to identify the optimal age to start enrolling cohorts and determine the agents that should be promoted.
    • If starting a chemoprevention agent at age 60 years is as effective as it is at age 40, patients could save years of the lifestyle changes involved.
    • Older persons should be oversampled in ongoing, randomized, clinical trials.
    • Enrollment strategies should be developed for older patients.
    • Biorepositories of tissue samples from older patients should be established.
    • For both screening and prevention studies, sufficient statistical power is needed to study race and cultural group differences as well as to stratify by age and gender.
    • Intermediate endpoints, such as functional ability, should be included.
  3. Develop models for decision making at the individual and clinical levels, including population forecasting for specific tumors. Develop models of academic research as well as community networks. Models can be used to:
    • Synthesize available data to extend the time horizon of observation to answer new questions;
    • Assist clinical decisions by weighing the risks and benefits of a given action;
    • Evaluate upper age limits for prevention and screening decisions;
    • Determine the role of individual preferences in prevention or screening decisions; and
    • Assess the risks, benefits, and costs of new prevention or early detection technologies.

Research Barriers

  • Research infrastructure for prevention and screening activities is lacking within cancer centers, across cancer centers, and in cancer center partnerships with communities.
  • Few investigators study both aging and cancer, and no common language exists to evaluate older individuals.
  • Collaboration between and among centers should be encouraged.

Caveats

In the final plenary session, Dr. Mandelblatt offered three caveats:

  • The research priorities were the opinion of one group,
  • The reliability and validity of the priority-setting process have not been validated, and
  • The working group had no input from older consumers in its discussion.

Page last updated Feb 16, 2008