Breast Cancer Screening
Breast Cancer As A Health Issue
Breast
cancer is a disease for which there is no foreseeable cure, and indications are
that the incidence will remain high. The American Cancer Society estimates that
more than 211,300 women were diagnosed with breast cancer in 2003, and almost
39,800 will die.
Although breast cancer remains a significant form of cancer
mortality for women, in 1996 an overall decrease in mortality was reported.
Because treatment is extremely effective with Stage I tumors, increases in
mammography screening have influenced breast cancer mortality.
Early Screening Test In Breast Cancer
When discovered
early, breast cancer victims may anticipate a 97% chance for complete cure.
Prospective mortality-based studies have demonstrated the effectiveness of
mammography screening, particularly in women 50-70 years of age, and therefore
most organizations recommend periodic screening beginning at age 50.
Recommendation for Screening
Recently,
mammography recommendations have been expanded to include women 40 to 49.
Consequently, both the American Cancer Society and the National Cancer
Institute now recommend screening beginning at age 40. Obviously, breast cancer
screening by mammography does not magically become effective at age 40 or 50 or
60, and one mistake that fueled controversy was comparing one decade to
another.
Comparing women aged 40 to 49 with women 50 and over creates
artificial boundaries that cause much confusion. Now that the American Cancer
Society and National Cancer Institute are in agreement, energy may be focused
on other issues.
Breast Examination And Outcomes
The
effectiveness of clinical breast examination is not as clear as that of
mammography, although it is currently recommended. Some studies demonstrating a
decrease in mortality for mammography have included clinical breast
examination, but the independent effect of the latter has not been studied.
In
addition, the efficacy of breast self-examination (BSE) has been documented
although not in randomized, prospective mortality-based trials. To date,
retrospective studies have found that BSE may detect an earlier stage of
disease or smaller tumor size.
Reliability of Screening
Despite
its apparent effectiveness, breast cancer screening is not used to its fullest
advantage. While screening rates may approach 70% to 74%, rates are lower for
minorities and women over 65. The rates for consistent mammography screening at
recommended intervals are not good.
Rates for mammography in 2000 ranged from
57%-72%. Rates for clinical breast examination and mammography were higher,
ranging between 37.3% and 69%. Recent data indicate that women may report BSE
practice as frequently at seven to eight times a year but have low proficiency
scores.
Potential of Breast Screening
It
is obvious that breast cancer screening has the potential to reduce mortality
and morbidity from this dreaded disease. Breast cancer screening rates,
although increasing. are not optimal. Most problematic is the fact that women
do not follow current recommendations for screening.
Minority rates for
follow-up are dismal, and access to care is a real issue. This health-promoting
detection activity is of primary importance to nurses in all areas of practice.
Nurses are in an optimal position to increase all three screening methods
(mammography, clinical breast examination, and BSE).
Interventions to promote
mammography and teach BSE can be carried out during general health promotion or
while women are being seen for other reasons. Clinical breast examination is a
skill that should be learned by all nurse practitioners and conducted yearly on
all women aged 20 and over.
Theoretical Assumptions About Mammography
Several
important theoretical variables have been tested for relationships to breast
cancer screening-in particular, mammography and BSE. The theory that has
generated the most research is the health belief model.
The health belief model
was initially conceptualized in the early 1950s to predict preventive behaviors
such as influenza inoculations (Rosenstock, 1966). As originally formulated,
the health belief model included the variable of perceived threat to health,
which included the concepts of risk of contracting the disease (perceived
susceptibility) and personal cost should the disease be contracted. (Perceived
seriousness).
In addition, benefits: and barriers to taking a preventive action
were predicted to influence the health behavior. In 1988, the concept of
self-efficacy, or perceived confidence in carrying out a preventive behavior,
was added to the health belief model.
Other
theories that have been used to predict breast cancer screening have included
Fishbein and Ajzen’s (1975) theory of reasoned action, which postulates that
two major concepts are related to breast cancer screening: (a) beliefs and
evaluations of these beliefs and (b) social influence.
Social influence is also
composed of two components: beliefs of significant others and the influence of
significant others on the individual. Most recently, the transtheoretical model
has been. tested with mammography use and found to predict behavior (Prochaska
et al., 1994). This model defines the outcome in terms of stages of
preparedness to engage in a health-promoting activity.
In addition to the
factors involved in these models, descriptive research suggests that breast
cancer screening is influenced by knowledge, previous health habits, particular
demographic characteristics, and health care systems.
A
number of studies spanning over a decade have used various models to predict
mammography screening. In general, attitudinal variables such as perceived
susceptibility, perceived benefits to screening, and perceived barriers to
screening have been predictive of mammography.
Rakowski and co-workers (1992)
found that perceived pros (benefits) and cons (barriers) varied across stages
of mammography. The most consistent predictors of mammography use have been
physician recommendations and barriers. The latter have included perceived lack
of need, fear of results, fear of radiation, cost, pain, time, and
inconvenience.
Recently, the trans-theoretical model has been used for
predicting mammography by postulating that women move through a series of
stages from precontemplation, or not thinking about mammography, to maintenance
of mammography over time.
Descriptive
studies to predict BSE have spanned the past 2 decades. Again, the variables of
perceived susceptibility, benefits, and barriers have been significantly
related to BSE. A less significant prediction of BSE compliance has been
physician recommendation.
Instead, women who were taught personally and
returned a demonstration have been found to comply at higher rates. A major
problem with BSE research has been the measurement of outcomes. In many earlier
studies women were asked how many times they examined their breasts, and this
was used as the operational measure of compliance.
Later, self-report
proficiency scales were widely used. Research has shown that there is often
little correlation between reported frequency and proficiency, indicating that
even if women practice BSE, they may not be doing it proficiently enough to
detect lumps.
Actual
measurement of BSE proficiency also has been problematic. The best studies have
used trained observers to watch women either complete BSE or identify silicon
lumps embedded in models. Subjective norms, as identified in the theory of
reasoned action, have been predictive in some studies.
Most research has
identified low to moderate correlations between attitudinal variables and BSE.
Perceived confidence for completing self-examination has been one of the
strongest predictors.
Intervention
research for both mammography and BSE has built on the descriptive studies of
earlier decades. Interventions have ranged from multistate community
interventions to individual patient-oriented interventions.
Many of the
individually focused interventions targeted perceptions of risk, benefits, and
barriers, multistrategy interventions often targeted physician recommendation,
which had been found to be an important predictor of mammography screening.
Various ways of delivering messages have been tried, including the media,
telephone delivery, tailored letters or postcards, and in-person counseling.
Access has been identified as a problem, as shown by the fact that persons in
health maintenance organizations (HMOs) consistently have higher rates of
mammography screening than do patients in private medical practice.
Access-enhancing interventions have included the use of mobile vans, which
provide casier access for women with transportation problems.
Costs of
mammography for indigenous women continue to be a problem, although agencies
such as the American Cancer Society and Little Red Door have helped to defray
these costs. Social network interventions have been effective with minority
groups.
Peer leaders can sometimes be important links for low-income, African
American, or Hispanic women. Most interventions, especially those based on
sound theory, have been successful in increasing mammography.
Interventions
addressing BSE often focus on teaching women the correct skills for practice .
Many of the interventions use educational strategies, with or without
counseling, related to the theoretical constructs of perceived susceptibility,
benefits, and barriers.
Many studies have used reminder systems or self-prompts
to increase practice. Interventions have ranged from handing out pamphlets to
one-to-one teaching sessions with return demonstrations.
Studies using models
to identify lumps have been the most vigorous. Studies that include personal
demonstrations, guided feedback, and both cognitive and personal instruction
evidence the greatest increase in proficiency.
Descriptive
and intervention studies based on similar theories of breast cancer screening
have extended over the past 2 decades. The major difference in relation to
promoting mammography is the addition of physician recommendation. Physician
recommendation is important both because medical advice is related to
mammography and because an order may be necessary to obtain a mammogram.
For
BSE, personal teaching has been found to be a most important predictor. We now
know enough about breast cancer screening to make certain recommendations for
nursing practice. For both BSE and mammography, clinicians must take into
account the individual’s perceptions about their susceptibility to breast
cancer.
If this perceived susceptibility is unrealistically low, efforts must
be made to paint a more accurate picture. Perceived benefits and barriers to
both mammography and BSE also should be addressed and individualized strategies
developed.
For BSE teaching, the set of skills needed to complete this exam and
observation of proficiency will be important. A major future direction related
to mammography will be to increase interval compliance.
Breast
cancer screening research has broad implications for increasing other health
behaviors, such as colorectal or prostate screening. Preventive behaviors such
as the use of skin protection and adherence to low-fat diets can also be
targeted for intervention trials.
Finally, nurses must actively encourage
public policy decisions that increase screening access for all people.