Cancer Prevention and Control Research in the 21st Century
A variety of issues related to preventing and controlling cancer in
the next century were presented to the President's Cancer Panel by researchers,
advocates, and consumers at its November 17 meeting, hosted by the University
of Arizona Cancer Center in Tucson. In response to data indicating that
more than one-half of all cancers are preventable, a call was made to increase
the proportion of resources devoted to cancer prevention and control research.
Advances in basic science have enabled detection of a vast array of
molecular events that lead to cancer, and this knowledge is growing. As
causes and mechanisms of cancer are elucidated, an increasing number of
opportunities for research become available, and improved strategies for
prevention become possible. It was predicted that a blending of scientific
disciplines (e.g., epidemiologic, molecular, behavioral, nutritional) will
evolve to address future research questions. Cancer risks related to environmental
exposures, lifestyle, diet, and other factors will be examined in the context
of genetic susceptibilities and the molecular processes of specific cancers.
Chemoprevention was identified as a critical strategy in this evolution.
Given that cancer is an often lengthy process from initiation to the eventual
detection of disease symptoms, researchers hope to develop chemopreventive
agents that will block this process at different stages. Promising clinical
trials are underway, for example, to identify agents that block UVB pathways
that signal cancer phenotypes following sun exposure. If this is successful,
a new market may develop for sunscreens that incorporate topical, medicinal
agents to halt the progression and incidence of skin cancer. Lifestyle
factors such as diet and physical activity are also being studied to determine,
molecularly, how they may lead to or protect against some cancers (e.g.,
breast, colon).
The ability to identify individuals at risk of cancer-via genetic or
molecular markers-also promises to change the way we think about cancer
prevention and control. The Panel heard that future interventions will
be designed for high-risk, moderate-risk, and low-risk groups instead of
assuming all individuals respond the same way to carcinogenic exposure.
Specific pathways for prevention will exist for specific groups.
Dr. Otis Brawley, Director, Office of Special Populations at the National
Cancer Institute, predicted that the application of this growing body of
knowledge could raise significant ethical dilemmas for research and medicine
in the 21st century. He cautioned that our knowledge should not get ahead
of our wisdom. Other speakers expressed an imperative to use gains in knowledge
to redress disparities in cancer rates among poor, underserved, and racial/ethnic
populations in the next millennium. Many examples of such disparities were
provided. Despite progress, for example, in controlling cervical cancer
mortality in the United States, a disproportionate number of Hispanic women
still die from this disease and it is the leading cause of death for women
in developing countries.
A number of promising developments were presented. The use of telemedicine
(e.g., telecolposcopy) in rural settings to improve access to and accuracy
of cancer screening and diagnosis is being demonstrated. This technology
could enable underserved populations to obtain the same specialized expertise
available at large medical centers without leaving their communities. Biobehavioral
approaches to prevention are also showing positive results. One smoking
cessation study reported higher rates of long-term cessation when chemical
intervention is combined with behavioral support.
A significant challenge for the future, the Panel learned, is shaping
messages and developing tools to motivate people to adopt health promoting
behaviors. As one advocate stated, good science is important, but so is
the ability to deliver "scientific" messages to the public. Tailoring
messages and materials to the variety of audiences and subpopulations in
this country is particularly difficult because not everyone learns or is
motivated in the same way. This problem is especially evident among adolescents,
many of whom some studies are finding, react unfavorably to the messages
delivered in current anti-smoking campaigns.
In the 21st century, urged Dr. Harold Freeman, Chair of the Panel, we
must also continue to promote a well-rounded cancer research and application
program driven by discovery, testing, translation, and access. This is
the key to continued progress in the war against cancer. Policies to ensure
access to intervention and treatment must be implemented as the ability
to screen for and detect cancer improves. "Screening doesn't cure
cancer," Dr. Freeman noted. "There need to be ways for people
to be treated irrespective of their ability to pay."
It was suggested that if the paradigm in this century has been "medical
oncology" and a focus on treatment, the new paradigm for the 21st
century should be "preventive oncology"- intervening with persons
identified as at-risk, but without symptoms of cancer. This paradigm moves
from a "reactive" cancer care system to one that is proactive
and participatory and reorients our current ideology from "sick care"
to "health care." The opportunities that exist under such a paradigm
are truly inspiring.
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