Transcript What Is Cancer Screening?

Dr.Azarm
INTRODUCTION
Dr.Azarm
INTRODUCTION
Cancer
deaths exceed seven million
worldwide each year, despite overwhelming
evidence that many malignancies are
preventable
nearly half a million people die from cancer
each year in the United States (US) alone
It is estimated that 50 percent of cancer is
preventable
INTRODUCTION
risk
factors (account for two-thirds of all
cancers in the US
–tobacco use,
–excess weight,
–poor diet,
–inactivity
Dr.Azarm
INTRODUCTION
nine
modifiable risks were identified as the cause of
35 percent of cancer deaths worldwide:
–smoking,
–alcohol use,
Harvard Report on
–diet low in fruit and vegetables,
Cancer Prevention
Volume 2:
–excess weight,
Prevention of
–inactivity,
Human Cancer.
Cancer Causes
–unsafe sex,
and Control
–urban air pollution,
1997; 8:S1.
–use of solid fuels, and
–contaminated injections in health-care settings
INTRODUCTION
Lifestyle
issues which promote cancer
are also risk factors for other diseases,
such as stroke, heart disease, and
diabetes.
Dr.Azarm
TOBACCO
USE
–kills approximately 5 million people each year
–mostly through
malignancy,
cardiovascular, and
respiratory disease
–Approximately one-half of all smokers die of a
tobacco-related disease, and
–adult smokers lose an average of 13 years of life
due to this addiction
TOBACCO
USE
–Smoking is responsible for approximately 30 percent of
all cancer-related deaths in the US
–lung cancer, increasing risk 10 to 20-fold
–causative factor for
leukemia as well as cancers of
the oral cavity,
nasal cavity,
paranasal sinuses,
nasopharynx,
larynx,
esophagus,
pancreas, liver, stomach, cervix, kidney, large bowel, and
bladder
TOBACCO
USE
–smoking to more aggressive prostate
cancers
–Smoking cessation leads to reduced risk of most
tobacco-related diseases and a decrease in all
cause mortality
–The health benefits of quitting can be seen at all
ages and can be measured almost immediately
after cessation
DIET
-Dietary fat
–No clear link has been found between total fat intake
and colon or breast cancer but the data are more
convincing for prostate cancer and endometrial cancer
–A diet high in animal fat may be an important
factor in the development of prostate cancer
intake of large amounts of alpha-linoleic acid and low
amounts of linoleic acid appear to increase risk
serum levels of testosterone are lower in men who
decrease their fat intake
DIET
-Red meat
–elevate risk of colorectal cancer in both men and
women
–several factors have been suggested including
heme content in the meat, animal fat, and
carcinogens produced when the meat is cooked
at high temperatures.
DIET
-Fruits and vegetables
–no association was seen between either total or
specific category of fruit and vegetable intake and
colon cancer risk
T
I
Prospective study of fruit and vegetable consumption and incidence of colon
and rectal cancers.
A
U
Michels KB; Edward Giovannucci; Joshipura KJ; Rosner BA; Stampfer MJ;
Fuchs CS; Colditz GA; Speizer FE; Willett WC
S
O
J Natl Cancer Inst 2000 Nov 1;92(21):1740-52.
DIET
-Fruits and vegetables
–Evidence is stronger for a link between prostate
cancer and tomato products
–Lycopene, a carotenoid found in tomatoes, has
been postulated to be responsible for this benefit
but there are no data from well-designed clinical
trials to support this hypothesis
T
I
Prospective study of fruit and vegetable consumption and incidence of colon
and rectal cancers.
A
U
Michels KB; Edward Giovannucci; Joshipura KJ; Rosner BA; Stampfer MJ;
Fuchs CS; Colditz GA; Speizer FE; Willett WC
S
O
J Natl Cancer Inst 2000 Nov 1;92(21):1740-52.
DIET
-Dairy
–relationship of dairy food intake and ovarian
cancer found no evidence of association in case
control studies
– OTHER three prospective cohort studies did
demonstrate increased risk of ovarian cancer with
high intake of dairy foods
DIET
-Fiber
–reduce the risk of heart disease [40,41] and
diabetes [42,43], but its effect on cancer risk
reduction is less certain
DIET
-Glycemic load
–Insulin and insulin-like growth factors promote
cell proliferation, and it is hypothesized that
hyperinsulinemia may promote certain cancers
DIET
-Omega-3 fatty acids
–there is no association between omega-3 fatty
acids and cancer risk for 11 different types of
cancer
–Dietary supplementation with omega-3 fatty
acids is unlikely to prevent cancer.
T
I
Effects of omega-3 fatty acids on cancer risk: a systematic review.
A
U
MacLean CH; Newberry SJ; Mojica WA; Khanna P; Issa AM; Suttorp MJ; Lim YW;
Traina SB; Hilton L; Garland R; Morton SC
S
O
JAMA. 2006 Jan 25;295(4):403-15.
DIET
-VITAMINS AND NUTRIENTS
–Several nutritional components have been
shown to affect cancer risk, but the role of
vitamins is less certain
–neither vitamin C nor vitamin E supplementation
was beneficial for prevention of the cancers
evaluated
TI
Antioxidants vitamin C and vitamin e for the prevention and treatment of cancer.
AU
Coulter ID; Hardy ML; Morton SC; Hilton LG; Tu W; Valentine D; Shekelle PG
SO
J Gen Intern Med. 2006 Jul;21(7):735-44.
DIET
-VITAMINS AND NUTRIENTS
–A 2006 National Institutes of Health (NIH)
consensus conference panel concluded that
"present evidence is insufficient to recommend
either for or against the use of multivitamin
supplements by the American public to prevent
chronic disease"
TI
Antioxidants vitamin C and vitamin e for the prevention and treatment of cancer.
AU
Coulter ID; Hardy ML; Morton SC; Hilton LG; Tu W; Valentine D; Shekelle PG
SO
J Gen Intern Med. 2006 Jul;21(7):735-44.
DIET
-VITAMINS AND NUTRIENTS
–It has not been proven that multivitamin and
mineral supplements provide added benefit to a
balanced, healthful diet
T
I
The efficacy and safety of multivitamin and mineral supplement use to prevent
cancer and chronic disease in adults: a systematic review for a National
Institutes of Health state-of-the-science conference.
A
U
Huang HY; Caballero B; Chang S; Alberg AJ; Semba RD; Schneyer CR; Wilson
RF; Cheng TY; Vassy J; Prokopowicz G; Barnes GJ 2nd; Bass EB
S
O
Ann Intern Med. 2006 Sep 5;145(5):372-85. Epub 2006 Jul 31.
DIET
-VITAMINS AND NUTRIENTS -Vitamin D
–may reduce the risk of colon cancer
–Direct effects of vitamin D on colonic epithelial
cells have been described
–Vitamin D may also decrease cancer risk through
improved calcium absorption
–prostate cancer did not demonstrate a
relationship
–breast cancer may have a protective effect
DIET
-VITAMINS AND NUTRIENTS -Vitamin D
in men was seen with an increment of 25
nmol/L in predicted 25(OH)D level in data
derived from the US Health Professionals
Follow-Up Study
This incremental level of serum 25(OH)D is
not readily achieved with diet (one glass of
milk would be predicted to increase the
plasma level only by 2 to 3 nmol/L), and
would require supplementation with at least
1500 IU vitamin daily
DIET
The
-VITAMINS AND NUTRIENTS -Vitamin D
authors raise a question whether
limiting sun exposure, to decrease skin cancer
risk, might increase the mortality risk for
other cancers.
DIET
-VITAMINS AND NUTRIENTS -Calcium
–Increased calcium intake
reduced risk of colorectal cancer
increased risk of prostate cancer
–700 mg/day
 protection against colorectal cancer
without significantly increasing prostate cancer risk.
DIET
-VITAMINS AND NUTRIENTS -Calcium
–Calcium
in the colon
–may offer protection by
Directly reducing epithelial cell proliferation,
Indirectly by binding secondary bile acids and ionized
fatty acids
–total calcium over 2000 mg/day from both diet
and supplementation was linked to a 20 percent
increase in prostate cancer risk
DIET
-VITAMINS AND NUTRIENTS -Selenium
–higher intake of selenium decreases the risk of a
variety of tumors
–significant mortality reduction in cancers of
lung
colon
prostate
–Selenium and Vitamin E Cancer Prevention Trial
(SELECT) will provide valuable information on the
overall risks and benefits of selenium
DIET
-VITAMINS AND NUTRIENTS -Folate
a decrease in breast and colon cancer risk,
especially in individuals who consume alcohol
supplementation with a multivitamin containing
folic acid provided even greater benefit
increased dietary folate and vitamin B6 intake
lowered colorectal cancer risk
reduced risk for pancreatic cancer
studies did not demonstrate an association
between low dietary intake of folate and breast
cancer
DIET
-VITAMINS AND NUTRIENTS -other vitamin supplements
Vitamin
E (600 IU alpha-tocopherol every
other day)
–did not prevent invasive cancer in a 10 year
follow-up to the Women's Health Study, evaluating
healthy women age 45 years and older (mean age
55 years)
–One study did find a decrease in risk for prostate
cancer with vitamin E supplementation in male
smokers
DIET
-VITAMINS AND NUTRIENTS -other vitamin supplements
Beta carotene
–may increase the incidence of lung cancer
incidence and mortality in patients with risk
factors (smokers or asbestos exposure)
–Beta carotene did not decrease cancer incidence
in studies of American women [110] and men
DIET
-VITAMINS AND NUTRIENTS -other vitamin supplements
Beta carotene
–in rural China with baseline deficiencies in
micronutrients
a combination of beta-carotene, selenium, and zinc
–decreased the incidence of noncardia stomach cancer,
–but not other intestinal malignancies
ALCOHOL
–increases the risk of cancers of
colon,
breast
Oropharynx
esophagus
–Moderate alcohol use
has beneficial effects on cardiovascular health,
consumption of as little as one drink per day has
been associated with an increase cancer risk
ALCOHOL
mechanisms
–solvent properties may allow carcinogens to
penetrate cell membranes
–increases estrogen levels
–impacts folate metabolism
–act as an irritant, causing increased cell
production
–transporter carrying carcinogens
–as a prometabolite for identified carcinogens
PHYSICAL
INACTIVITY
Decreased physical activity
increase the risk for cancer,
in addition to multiple other diseases
Over
60 percent of US adults are not
regularly active,
including 25 percent who are almost entirely
sedentary
sedentary lifestyle is associated with 5 percent
of cancer deaths
PHYSICAL
INACTIVITY
–Physical activity is associated with a decreased
risk of colon and breast cancer
–negative correlation between moderate to
strenuous exercise and ER-negative, but not ERpositive, breast cancer
–activity offers some protection against
endometrial and prostate cancer
–physical activity may reduce the risk of lung
cancer
PHYSICAL
INACTIVITY
the protective effect of activity goes beyond
its impact on body weight
PHYSICAL
INACTIVITY
mechanisms
–reduction in circulating levels of insulin,
hormones, and other growth factors
–impact on prostaglandin levels; improved
immune function, and
–altered bile acid metabolism
PHYSICAL
INACTIVITY
Physical activity during certain periods of
life, such as adolescence, may offer additional
protection against disease
The optimal duration, intensity, and
frequency of physical activity that may afford
cancer protection is unknown.
EXCESS
WEIGHT
–65 percent of US adults are overweight
–over 30 percent are considered obese
EXCESS
WEIGHT
with an increase in the risk of multiple
cancers including
–colorectal,
–postmenopausal breast,
–endometrial, renal, and
–esophageal cancer, with
a
population attributable risk from
–9 percent (postmenopausal breast cancer)
–to 39 percent (endometrial cancer)
EXCESS
WEIGHT
Obesity may also increase risk for cancer of
–prostate,
–liver,
–gallbladder,
–pancreas,
–stomach,
–ovary, and
–cervix
–non-Hodgkin's lymphoma
–multiple myeloma
EXCESS
WEIGHT
obesity in the US may account for
–14 percent of cancer deaths in men and
–20 percent of cancer deaths in women
EXCESS
SUN EXPOSURE
–Over 1 million cases of skin cancer, including
basal cell and squamous cell carcinoma, are
diagnosed each year
–over 59,000 cases of malignant melanoma in the
US in 2005 [9], and the incidence continues to
rise
–most skin cancers are curable
–Radiation from the sun is the primary cause
 both melanomatous and non-melanomatous skin
cancer.
EXCESS
SUN EXPOSURE
–correlate with total lifetime sun exposure
–Cumulative sun exposure may also increase
melanoma risk
–repeated intense exposures leading to blistering
burns may be even more dangerous
EXCESS
SUN EXPOSURE
Recommendations for sun protection
–All individuals should limit the time spent in the
sun,
especially between the hours of 10 am and 3 pm,
–wear hats, sunglasses, and other protective
clothing,
–use sunscreen
EXCESS
SUN EXPOSURE
Recommendations for sun protection
–majority of lifetime sun exposure usually occurs
during childhood and adolescence
–protective behaviors early in life will provide the
greatest benefit
–Organization recently recommended against
tanning bed use by anyone under the age of 18
INFECTION
–17 percent of all new cancers worldwide are due
to infections
–Viruses may increase cancer risk through
cellular transformation,
disruption of cell cycle control,
increased cell turnover rates,
immune suppression
INFECTION
Human papillomavirus (HPV)
anogenital cancers [140]
with cervical and other
Hepatitis
B (HBV) and C (HCV) with hepatocellular
carcinoma [141]
Human T-cell lymphotropic virus (HTLV-I) with adult T cell
leukemia [142]
Human immunodeficiency virus (HIV-I) with Kaposi sarcoma
and non-Hodgkin's lymphoma [9]
Human herpes virus 8 (HHV-8) with Kaposi sarcoma and
primary effusion lymphoma [143,144]
Epstein-Barr virus (EBV) with Burkitt's lymphoma [143]
Helicobacter
pylori (H. pylori) with gastric cancer
INFECTION
–The majority of these viruses are spread through
contact with infected blood or body fluids
–Vaccinations for HBV and HPV are particularly
promising
–Excess alcohol use may play a role in cancer
development in patients with chronic HBV and
HCV infections and should be avoided
–antiviral therapy may reduce the risk of cancer
–Retroviral therapy for HIV infection reduce the
incidence of AIDS-related lymphoma
INFECTION
–The majority of these viruses are spread through
contact with infected blood or body fluids
–Vaccinations for HBV and HPV are particularly
promising
–Excess alcohol use may play a role in cancer
development in patients with chronic HBV and
HCV infections and should be avoided
–antiviral therapy may reduce the risk of cancer
–Retroviral therapy for HIV infection reduce the
incidence of AIDS-related lymphoma
CHEMOPREVENTION
Selective
estrogen receptor modulators
and breast cancer -Tamoxifen
–an estrogen receptor antagonist with both
estrogen agonist and antagonist properties
–It is approved in the US for both primary and
secondary prevention in high-risk women
CHEMOPREVENTION
Selective
estrogen receptor modulators
and breast cancer -Tamoxifen
–Breast Cancer Prevention Trial (NSABP P-I),
–women at increased risk for breast cancer
age >60,
history LCIS,
calculated five year risk >1.66 percent according to
the Gail model
CHEMOPREVENTION
Selective
estrogen receptor modulators and
breast cancer -Tamoxifen
–an approximate 50 percent reduction in the relative risk
of both invasive and noninvasive (ie, ductal and lobular
carcinomas in situ) breast cancer with tamoxifen.
–Risk was reduced only for estrogen receptor positive
tumors.
–Women in the tamoxifen arm had an approximately twofold increased incidence in endometrial tumors (cancers
and uterine sarcomas), pulmonary embolism, deep vein
thrombosis (DVT), and stroke
CHEMOPREVENTION
Selective
estrogen receptor modulators
and breast cancer -Tamoxifen
Because of the potential for serious side
effects, the US Preventive Services Task Force
(USPSTF) has recommended against routine
use of tamoxifen for breast cancer prevention
in women of average risk.
CHEMOPREVENTION
Selective
estrogen receptor modulators
and breast cancer -Raloxifene
–— Raloxifene is a selective estrogen receptor
modulator (SERM) that is currently approved for
the prevention of osteoporosis, but not for the
prevention of breast cancer
–STAR trial suggest that raloxifene is as effective
as tamoxifen in reducing the incidence of invasive
breast cancers in high-risk women, but with fewer
of the most serious side effects associated with
tamoxifen
CHEMOPREVENTION
Selective
estrogen receptor modulators
and breast cancer -Raloxifene
–There are no data on the use of raloxifene in
premenopausal women, and it should not be used
in this group
CHEMOPREVENTION
Aspirin
and other anti-inflammatory drugs
–reducing colorectal cancer risk,
–and possibly effective for other cancers
–may cause cell cycle arrest or apoptosis
CHEMOPREVENTION
Aspirin
and other anti-inflammatory drugs
–The optimal dose of aspirin,
however has not been established [161].
Low dose aspirin (100 mg every other day) did not
prevent total cancer death, or incidence of breast,
colorectal, or lung cancer, when compared with
placebo, at 10 year follow-up
Full dose aspirin ( 325 mg) taken daily for a minimum
of five years
–decrease the incidence of colorectal cancer in the Cancer
Prevention Study II Nutrition Cohort
CHEMOPREVENTION
Aspirin
and other anti-inflammatory drugs
–There is good evidence that chronic use of
aspirin, at doses suggested to decrease the
incidence of colorectal cancer,
increases the risk for gastrointestinal bleeding and
hemorrhagic stroke
increases risk for renal failure and hypertension
CHEMOPREVENTION
Aspirin
and other anti-inflammatory drugs
–USPSTF and the American Cancer Society do not
recommend aspirin or NSAID use to prevent
colorectal cancer for average risk patients
CHEMOPREVENTION
Finasteride
and prostate cancer
–Compared to men in the placebo group,
the incidence of prostate cancer was decreased in the
finasteride group (18.4 percent versus 24.4 percent)
 but there was an increase in the absolute number
and proportion of high grade tumors
CHEMOPREVENTION
Finasteride
and prostate cancer
–Concerns about increased risk for high grade
prostate cancer dampened enthusiasm for the
use of finasteride as a chemopreventive agent
–It is premature to recommend the use of
finasteride as a chemopreventive agent in men at
high risk for prostate cancer, but clinicians should
feel comfortable about using finasteride in men
with large-gland BPH
CHEMOPREVENTION
SUMMARY
AND RECOMMENDATIONS
–Many cancers are preventable
–Basic lifestyle changes
have a tremendous impact on the rates of cancer
also protect against other chronic diseases
(cardiovascular disease, stroke, and diabetes)
CHEMOPREVENTION
General
lifestyle recommendations include:
Avoid tobacco
Be physically active
Maintain a healthy weight
Eat a diet rich in fruits, vegetables, and whole
grains, and low in saturated/trans fat
Limit alcohol
Protect against sexually transmitted infections
Avoid excess sun
Get regular screening


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
–
–
–
–
Tobacco use is responsible for 90 percent of all lung
cancer deaths, and is tied to multiple other cancers
The association of dietary fat, fruits, vegetables, and
fiber with cancer risk is largely unconfirmed.
Red meat consumption may promote colorectal cancer
high intake of tomatoes probably decreases prostate
cancer risk.


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
–
–
–
–
–
Vitamin D may reduce the risk of colorectal and
prostate cancer.
Calcium intake, at a minimum of 700 mg/day, may
protect against colorectal cancer
but high calcium intake (>2000 mg/day) increases
risk for prostate cancer.
Folic acid in diet has been associated with a
decreased risk of colon and breast cancer, especially
in women who drink alcohol;
data on multivitamin supplementation are inconsistent


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
– Alcohol intake, even in moderate quantities,
increases the risk for colon, breast,
esophageal and oropharyngeal cancer.


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
– Physical activity is inversely related to risk for
colon and breast cancer.
– Excess weight increases the risk of multiple
cancers.


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
– Skin cancer is directly related to sun exposure,
and melanoma rates are increasing.
– A history of blistering sunburns are of
particular risk for melanoma;
– cumulative sun exposure has more impact on
non-melanoma cancers.


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
– HPV, HCV, HTLV1, HIV, EBV, and H pylori
have been linked to human cancers.
– Exposure prevention, screening, and early
treatment for abnormal Pap smears and HIV
infection can prevent cancer


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:
– Chemoprevention may be helpful in high risk
patients but risks and benefits should be
weighed carefully.

Aspirin and NSAIDs offer protection against
adenomatous polyps and colorectal cancer, but are
not recommended for routine use in average risk
patients.


CHEMOPREVENTION
Specific factors associated with cancer risk
include the following:



Tamoxifen decreases incidence of breast cancer in
high risk women, but increases the risk for
thromboembolic disease and early stage
endometrial cancer.
Raloxifene is a reasonable alternative, but has not
been evaluated in premenopausal women
The use of finasteride as a chemopreventive agent
should be discussed with men who are interested
in preventing prostate cancer
–What
Is Cancer Screening?
–Evaluation of a Screening Test
–Breast Cancer Screening
–Cervical Cancer Screening
–Colorectal Cancer Screening
–Skin Cancer Screening
–Prostate Cancer Screening
–Lung Cancer Screening
–Adherence to Cancer Screening
–Future of Screening
The
goal of cancer screening
–detect cancer at an early stage when it is
treatable and curable
For
a screening test to be useful:
–the test or procedure should detect cancer
earlier than would occur otherwise,
–there should be evidence that earlier diagnosis
results in improved outcomes
Advances
in genetics and molecular biology
–will make it possible to detect cancer at earlier
and earlier stages along the carcinogenesis
pathway
–the line between prevention and screening may
narrow further, as it has for colorectal and
cervical cancers
The
National Cancer Policy Board
estimated that appropriate use of
screening among
–persons aged 50 and older could reduce
the mortality from colorectal cancer by
30% to 80%;
–women aged 50 and older could reduce
mortality from breast cancer by 25% to
30%,
–women aged 18 and older could reduce
the rate of cervical cancer mortality by
20% to 60%.
What Is Cancer Screening?
lead to early detection of asymptomatic or
unrecognized disease
acceptable
inexpensive tests or examinations
in a large number of persons
expeditiously to separate apparently well persons
who probably have disease from those who probably
do not.
What Is Cancer Screening?
The main objective of cancer screening is to:
– reduce morbidity and mortality from a particular cancer
among persons screened
What Is Cancer Screening?
Characteristics of Screening Tests versus Diagnostic
Tests
Screening
Diagnosis
Applied to asymptomatic
groups
Applied to symptomatic
individuals
Lower cost per test
Higher cost; all necessary tests
applied to identify disease
Lower yield per test
Higher probability of case
detection
Lower adverse
consequences of error
Failure to identify true positives
can delay treatment and worsen
prognosis
What Is Cancer Screening?
cancers
suitable for screening
–High morbidity and mortality,
–high prevalence in a detectable preclinical
state,
–possibility of effective and improved
treatment because of early detection, and
–availability of a good screening test with
high sensitivity and specificity,
–low cost, and
–little inconvenience and discomfort
What Is Cancer Screening?
cancers suitable for screening
–Breast CA
–Cervical CA
–colorectal CA
Evaluation of a Screening Test
If the test is abnormal,
–what are the chances that disease is present?
If
the test result is normal,
–what are the chances that disease is absent?
Evaluation of a Screening Test
The validity of a screening test
–Sensitivity and specificity address the validity of
screening tests
Sensitivity is the probability of testing positive if the
disease is truly present.
–As sensitivity increases, false-negative decreases
Specificity is the probability of screening negative if
the disease is truly absent.
–A highly specific test false-positive decreases
Evaluation of a Screening Test
The validity of a screening test
–Predictive value
is a function of sensitivity, specificity, and prevalence
of disease
PV+ is an estimate of test accuracy in predicting
presence of disease;
PV– is an estimate of the accuracy of the test in
predicting absence of disease
Definitions of Criteria for Evaluating a Screening Test
Truth (Diagnostic Classification)
Screening Test Results
Cancer Present
Cancer Absent
Positive
TP
FP
Negative
FN
TN
Sensitivity = TP/TP + FN x 100
Specificity = TN/FP + TN x 100
PV+ = TP/TP + FP x 100
PV– = TN/TN + FN x 100
Accuracy = TP + TN/TP + TN + FP + FN x 100
FN, false-negative (number of subjects with cancer who are incorrectly
classified as cancer-free by the test);
FP, false-positive (number of cancer-free subjects who are incorrectly classified
as having cancer by the test);
PV, predictive value; TN, true-negative
(number of cancer-free subjects who are correctly classified by the test);
TP, true-positive (number of subjects with cancer who are correctly classified
by the test).
Evaluation of a Screening Test
Measures of Effectiveness
–Potential benefits include
improved prognosis for those with screen-detected
cancers,
the possibility of less radical treatment,
reassurance for those with negative test results,
resource savings if treatment costs are reduced
because of less radical treatments
Evaluation of a Screening Test
Measures of Effectiveness
–The optimal outcome is a reduction in cancer
mortality
Evaluation of a Screening Test
Measures of Effectiveness
–Potential negative effects of screening include
 physical, economic, and psychological consequences
of false-positives and false-negatives,
the potential for overdiagnosis,
the potential carcinogenic effects of screening,
the labeling phenomenon.
Evaluation of a Screening Test
Measures of Effectiveness
–Potential negative effects of screening include
 physical, economic, and psychological consequences
of false-positives and false-negatives,
the potential for overdiagnosis,
the potential carcinogenic effects of screening,
the labeling phenomenon.
Evaluation of a Screening Test
Measures of Effectiveness
–Physicians should engage patients in discussions
of the risks and benefits of cancer screening
Table 22-5: Screening Guidelines for Breast, Colorectal, Prostate, and Cervical Cancers for Selected Health Care Organizations
Ty
pe
of
Ca
nc
er
American Cancer Society20
U.S. Preventive Services Task Force3
National Cancer Institute's Physician
Data Query (PDQ) System1
Br
ea
st
ca
nc
er
Annual mammography for women aged 40–69
y. No age cutoff. To the extent possible, a CBE
should be performed at the time of
mammography. Monthly BSE.136 Women aged
20–39 y should have a CBE from a health
professional every 3 y and should perform BSE
monthly.20
Recommends screening mammogram, with or
without CBE, every 1–2 y.
Mammography every 1–2 y for women age 40
y and older. Women at higher risk should talk
with their physicians about schedule.
Ce
rvi
cal
ca
nc
er
For all women who are, or have been, sexually
active or who have reached age 21 y, Pap test
and pelvic examination yearly with Pap tests
or every 3 y with liquid-based tests. At or
after age 30 y, women who have had 3 normal
tests can be screened every 2–3 y. Women
with risk factors (e.g., HPV infection) may
require more frequent screening. Screening is
not necessary for women who have had total
hysterectomies unless the surgery was for
treatment of cervical cancer.
Pap test every 1–3 y for all women who are
sexually active and/or have a cervix. No
evidence to support an upper limit, but age 65
y can be defended in women with a history of
normal and regular Pap tests.
Evidence strongly suggests a decrease in
mortality for regular screening with Pap tests
in women who are sexually active or who have
reached age 18 y. The upper limit at which
such screening ceases to be effective is
unknown.
Col
ore
cta
l
ca
nc
er
One of the following schedules for men and
women aged 50 y and over at average risk:
FOBT yearly; sigmoidoscopy every 5 y; FOBT
+ sigmoidoscopy every 5 y; colonoscopy
every 10 y; DCBE every 5 y. Those at high
risk for colorectal cancer should begin
screening earlier and/or more frequently.
Screening for colorectal cancer is strongly
recommended for men and women aged 50 y
and over. Several screening modalities are
effective. Good evidence has been shown that
periodic FOBT reduces mortality from
colorectal cancer, and there is fair evidence
that sigmoidoscopy alone or in combination
with FOBT reduces mortality. No direct
evidence has been shown for either
colonoscopy or DCBE.
FOBT either annually or biennially using
rehydrated or nonrehydrated stool specimens
in people aged 50 y and over decreases
mortality for colorectal cancer. Regular
screening by sigmoidoscopy in people over
age 50 y may decrease mortality from
colorectal cancer. Evidence is insufficient to
determine the optimal interval for such
screening.
Pro
sta
te
ca
nc
er
PSA test and DRE should be offered annually,
beginning at age 50 y, to men who have a life
expectancy of at least 10 y. Men at high risk
for cancer should start screening at 45 y. Men
should be given the information needed to
make informed decisions about prostate
cancer screening.
Evidence is insufficient to recommend for or
against routine screening for prostate cancer
using PSA testing or DRE.
Evidence is insufficient to establish that a
decrease in mortality occurs with screening by
DRE, transrectal ultrasound, or PSA.
Screening Guidelines for Breast, Colorectal, Prostate, and Cervical Cancers
for Selected Health Care Organizations
Type
of
Cancer
American Cancer
Society20
U.S. Preventive
Services Task
Force3
National Cancer
Institute's Physician
Data Query (PDQ)
System1
Breast
cancer
Annual mammography
for women aged 40–69
y. No age cutoff. To the
extent possible, a CBE
should be performed at
the time of
mammography. Monthly
BSE.136 Women aged
20–39 y should have a
CBE from a health
professional every 3 y
and should perform BSE
monthly.20
Recommends
screening
mammogram, with or
without CBE, every
1–2 y.
Mammography every 1–2
y for women age 40 y and
older. Women at higher
risk should talk with their
physicians about
schedule.
Table 22-5: Screening Guidelines for Breast, Colorectal, Prostate, and Cervical Cancers
for Selected Health Care Organizations
Type
of
Cance
r
American Cancer
Society20
U.S. Preventive Services
Task Force3
National Cancer Institute's
Physician Data Query
(PDQ) System1
Cervic
al
cancer
For all women who are, or
have been, sexually active
or who have reached age
21 y, Pap test and pelvic
examination yearly with
Pap tests or every 3 y with
liquid-based tests. At or
after age 30 y, women
who have had 3 normal
tests can be screened
every 2–3 y. Women with
risk factors (e.g., HPV
infection) may require
more frequent screening.
Screening is not necessary
for women who have had
total hysterectomies
unless the surgery was for
treatment of cervical
cancer.
Pap test every 1–3 y for all
women who are sexually
active and/or have a cervix.
No evidence to support an
upper limit, but age 65 y
can be defended in women
with a history of normal and
regular Pap tests.
Evidence strongly suggests a
decrease in mortality for
regular screening with Pap
tests in women who are
sexually active or who have
reached age 18 y. The upper
limit at which such screening
ceases to be effective is
unknown.
Type of
Cancer
American
Cancer
Society20
U.S. Preventive
Services Task Force3
National Cancer
Institute's Physician
Data Query (PDQ)
System1
Colorectal
cancer
One of the
following
schedules for
men and women
aged 50 y and
over at average
risk: FOBT
yearly;
sigmoidoscopy
every 5 y; FOBT
+ sigmoidoscopy
every 5 y;
colonoscopy
every 10 y;
DCBE every 5 y.
Those at high
risk for colorectal
cancer should
begin screening
earlier and/or
more frequently.
Screening for colorectal
cancer is strongly
recommended for men
and women aged 50 y
and over. Several
screening modalities are
effective. Good evidence
has been shown that
periodic FOBT reduces
mortality from colorectal
cancer, and there is fair
evidence that
sigmoidoscopy alone or in
combination with FOBT
reduces mortality. No
direct evidence has been
shown for either
colonoscopy or DCBE.
FOBT either annually or
biennially using
rehydrated or
nonrehydrated stool
specimens in people aged
50 y and over decreases
mortality for colorectal
cancer. Regular screening
by sigmoidoscopy in
people over age 50 y may
decrease mortality from
colorectal cancer.
Evidence is insufficient to
determine the optimal
interval for such
screening.
Type of
Cancer
American
Cancer
Society20
U.S. Preventive
Services Task Force3
National Cancer
Institute's Physician
Data Query (PDQ)
System1
Prostate
cancer
PSA test and
DRE should be
offered annually,
beginning at age
50 y, to men who
have a life
expectancy of at
least 10 y. Men
at high risk for
cancer should
start screening
at 45 y. Men
should be given
the information
needed to make
informed
decisions about
prostate cancer
screening.
Evidence is insufficient to
recommend for or against
routine screening for
prostate cancer using PSA
testing or DRE.
Evidence is insufficient to
establish that a decrease
in mortality occurs with
screening by DRE,
transrectal ultrasound, or
PSA.
Breast
Cancer Screening
lifetime breast cancer incidence is 7.8%,
Widely
accepted techniques for breast cancer
screening,
–mammography,
–clinical breast examination (CBE), and
–breast self-examination (BSE).
–No cancer screening test has been studied more than
mammography (with or without CBE).
Breast
Cancer Screening
Most trials have included women in their
40s,
 two trials began accrual at age 45.
One of the Canadian trials [the first National
Breast Cancer Screening Study (NBSS1)] was
designed to examine mammography and CBE
versus usual care for women in their 40s
Breast
Cancer Screening