بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم

CANCER PREVENTION

CANCER PREVETION INTRODUCTION Cancer deaths seven million half a million  die from cancer each year in the United States (US) alone It is estimated that 50 percent of cancer is preventable

CANCER PREVETION INTRODUCTION risk factors (account for two-thirds of all cancers in the US tobacco use, excess weight, poor diet, inactivity

CANCER PREVETION Harvard Report on Cancer Prevention Volume 2: Prevention of Human Cancer. Cancer Causes and Control 1997; 8:S1. INTRODUCTION nine modifiable risks were identified as the cause of 35 percent of cancer deaths worldwide: smoking, alcohol use, diet low in fruit and vegetables, excess weight, inactivity, unsafe sex, urban air pollution, use of solid fuels, and contaminated injections in health-care settings

CANCER PREVETION INTRODUCTION Lifestyle issues which promote cancer are also risk factors for other diseases, such as stroke, heart disease, and diabetes.

CANCER PREVETION

CANCER PREVETION 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

CANCER PREVETION

CANCER SCREENING –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

CANCER 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: should detect cancer earlier than would occur otherwise, should be evidence that earlier diagnosis results in improved outcomes

CANCER SCREENING 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

CANCER SCREENING 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%.

CANCER SCREENING 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.

CANCER SCREENING What Is Cancer Screening? The main objective of cancer screening is to: reduce morbidity and mortality from a particular cancer among persons screened

CANCER SCREENING What Is Cancer Screening?

CANCER SCREENING 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

CANCER SCREENING What Is Cancer Screening? cancers suitable for screening Breast CA Cervical CA colorectal CA Skin cancer

CANCER SCREENING 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?

CANCER SCREENING 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

CANCER SCREENING 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

CANCER SCREE NING 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).

CANCER SCREENING Evaluation of a Screening Test The optimal outcome is a reduction in cancer mortality

CANCER SCREENING 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.

CANCER SCREENING Evaluation of a Screening Test Measures of Effectiveness Physicians should engage patients in discussions of the risks and benefits of cancer screening

CANCER SCREENING

CANCER SCREENING 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).

CANCER SCREENING 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

CANCER SCREENING

بسم الله الرحمن الرحيم